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General information

Industrial extraction is a technical system that captures dust, smoke, sawdust, aerosols or exhaust gases directly at their source and directs them to a filtration unit. A correct system must have sufficient capture efficiency, appropriate air velocities in the ductwork and a filter designed not to impede production. The aim is not merely to meet hygiene standards but to maintain clean operations, protect machinery and personnel, and reduce cleaning and energy costs.

Industrial air filtration is used to separate solid particles, smoke or dust from the airstream before it is discharged into the hall or chimney. It protects the health of workers, technology and the environment while allowing clean air to be recirculated back into the hall if the application and legislation permit. With a high-quality textile filter, residual emissions are typically very low and pressure ratios remain stable.

An industrial filter operates by drawing contaminated air into the filtration chamber, where dust is captured on the surface of the filter media and clean air proceeds to the fan or back into the space. The collected dust is continuously removed through regeneration, most commonly using compressed air pulses. In fabric filters, the primary filtering element is not just the textile itself but also the stable dust cake formed on its surface.

In the industry, fabric bag and hose filters, cartridge filters, cyclones, wet scrubbers, electrostatic precipitators, and high-temperature ceramic or metal filters are predominantly used. For general dry dust collection, we prefer fabric filters; for pre-separation of coarse material, cyclones are recommended; and for hot flue gases, ceramic or stainless steel filter elements are the optimal choice. Wet scrubbers are only suitable where sludge management, moisture, and lower particulate matter removal efficiency are not problematic.

A suitable filtration system is selected based on the material being extracted, air flow rate, temperature, humidity, dust explosivity, required emissions and mode of operation. For welding and grinding we often recommend Jet BAG or Flat HOUSE textile filters; for wood and biomass, Flat WOOD; for hot exhaust gases, Ceramic JET or Steel JET; and for local extraction from conveyors, Local JET. The correct selection must also address the fan, ducting, waste removal, control system and safety components.

For the design, we require at least the technology type, number of extraction points, expected airflow rate, dust or smoke type, temperature, humidity, operating hours, required emission levels, and information on where the filter, fan, and exhaust can be installed. For explosive dusts, we also need ATEX parameters such as Kst, Pmax, MIE, and ignition temperatures. The more precise the input data provided, the more accurate will be the design of performance, pressure losses, filtration area, and cost. An on-site visit by a technician is ideal; however, if this is not possible, it is acceptable to send a video describing the issue.

We can prepare standard filtration unit proposals quickly thanks to our proprietary database of 3D models and proven design solutions. Delivery for smaller units typically takes six to eight weeks, while large central filters and hot exhaust systems require eight to ten weeks, depending on manufacturing, ATEX components, and installation. For larger systems, it is crucial to finalise the specifications clearly, as changes to flow rates, temperatures or layout during production can have a significant impact.

Yes, we also supply the filtration technology as a complete package: design, 3D modelling, manufacturing, pipework, fan, electrical systems, control and regulation, installation, and commissioning. For larger projects, we divide the equipment into transportable and assembly units to facilitate efficient transportation and on-site installation. After start-up, we verify flow rates, pressure losses, regeneration performance, and the functionality of safety components.

Yes. For our own installations, we handle the assembly, commissioning and subsequent training of operators. However, we also work with a number of partners in various countries. We train these partners and provide them with technical support so that they can carry out the installation and commissioning independently, ensuring customers have access to local service and support.

Yes. For our own installations, we provide servicing, regular maintenance, filter media replacements and modernisation of existing equipment. We also train our sales and service partners so they can carry out the servicing independently on-site. This ensures customers have access to prompt technical support without having to wait for technicians to travel from the Czech Republic.

An industrial filter is not a consumer good intended to last for several years. A well-designed filtration unit can reliably serve for 20 to 30 years or more with regular maintenance. During this period, the filter media and certain operational components are typically replaced several times. For this reason, many customers opt to modernise their existing filters rather than replace the entire system, as it is a more cost-effective solution.

The largest operational costs of industrial filtration units are not the filter bags, but the electricity consumption of the fan. Other costs include compressed air consumption for regenerating the filter media and the regular replacement of wear parts. Therefore, when designing filtration units, we focus primarily on low pressure drop and high energy efficiency, which have a much greater impact on total costs over 20 to 30 years of operation than the initial purchase price of the equipment.

Yes. Many older filtration units still have sufficient mechanical lifespan and do not need to be replaced with new ones. Modernisation can involve the use of modern filter media, fan replacement or optimisation, installation of a variable frequency drive, performance control based on pressure drop or actual airflow, and other modifications that reduce operating costs. In many cases, significant energy savings can be achieved without replacing the entire filtration unit.

Yes. Replacing an old filter with a new one while retaining the existing pipework is a common aspect of industrial extraction system upgrades. In most cases, there is no need to replace the entire ductwork network. We design new filtration units to maximise the use of existing infrastructure whilst reducing pressure drop and operating costs. The aim is not to replace everything, but to obtain more modern and energy-efficient equipment with minimal capital investment.

Yes. We service and supply spare parts for equipment from other manufacturers as well. However, we do not wish to build our business model on the premise that customers will purchase spare parts as frequently as possible. On the contrary, we strive to design filtration systems with a long lifespan, low pressure drop, and minimal maintenance requirements. We believe that long-term customer satisfaction is more important than revenue from servicing.

The most common faults in filtration systems are not caused by the steel structure itself, but by operational components. The issues we encounter most frequently include torn filter bags or cartridges, clogged dust hoppers, valve and regeneration membrane failures, motor or fan defects, and long-term neglect of maintenance. Most of these problems can be resolved without requiring a complete replacement of the filtration unit.

The most common symptom of an undersized extraction system is low suction power directly at the source of contamination. Another indicator is high pressure loss and the fact that the fan with a variable frequency drive operates almost continuously at 100% capacity. Such a system has no reserve for filter media clogging or potential production expansion. The result is inadequate extraction, higher energy consumption, and a deterioration in working conditions.

Filter media replacement is most commonly required in two scenarios. Either the filter media becomes damaged, allowing dust to penetrate to the clean side of the filter, or the media are so heavily loaded that regeneration can no longer maintain an acceptable pressure drop. This results in reduced suction power and higher electrical energy consumption. Timely replacement of filter media is usually more cost-effective than long-term operation with elevated pressure loss.

When designing an extraction system, it is crucial to accurately determine the required extraction capacity, the nature and volume of dust generated, and the actual operating hours of the equipment. Consequently, filters are designed differently for intermittent extraction compared to continuous three-shift operations. Factors such as temperature, humidity, abrasiveness, stickiness, or explosivity of the dust also play a significant role. The objective is not to design the largest possible filter, but rather an installation with adequate performance reserve, low pressure drop, and minimal operating costs.

Extraction merely transports contaminated air away from the source of pollution. If this air were discharged directly into a chimney without further treatment, the problem would simply be relocated elsewhere. Air filtration ensures the removal of dust, smoke, or other particulates, enabling compliance with emission limits and allowing cleaned air to be recirculated back into the production hall. Extraction handles the transport of air, while filtration addresses its purity.

Industrial extraction does not generate output in itself; therefore, its return on investment cannot be assessed in the same way as that of production technologies. Its true value lies in enabling long-term and safe manufacturing operations, protecting employees, and helping to meet legislative and emission requirements. Simply put – quality extraction does not make money, but it enables you to earn it.

The most common mistake is the attempt to purchase the smallest and cheapest equipment possible. Undersized air flow or insufficient filter area leads to high pressure drop, low suction power, and unnecessarily high operating costs. In some applications, the use of cartridge filters where filter bags would be more suitable in terms of lifespan, pressure drop, and maintenance costs also poses a problem. A correct design should be based on long-term operating costs rather than just the initial purchase price.

Yes. For a range of applications, filtered air can be returned to the production hall after thorough filtration, significantly reducing heating costs during winter. This solution is particularly suitable for dusty environments without the presence of VOCs, odorous substances or other harmful gases. If the extracted air contains volatile organic compounds, odours or other gaseous pollutants, it is usually necessary to exhaust the cleaned air outside the building or add an additional purification stage.

Centralised extraction is particularly suitable for operations with a higher number of pollution sources. A single filtration unit can service multiple machines or technological units simultaneously, which is generally more cost-effective than operating several standalone filters. This provides the customer with lower capital investment costs, simpler maintenance, fewer spare parts, and reduced electrical energy consumption thanks to the ability to control output according to actual demand.

Industrial filtration units are not maintenance-intensive. In most cases, regular visual inspections approximately twice a year are sufficient. We recommend monitoring pressure drop, regeneration status, hopper emptying, and any potential leaks. A more thorough inspection once a year by the manufacturer or a trained service partner is advisable; however, for correctly designed equipment, this is not an essential requirement.

An industrial filtration system typically comprises an intake duct, the filtration unit, a fan, an exhaust duct, and an electrical control system. Each of these components significantly impacts overall functionality, pressure drop, and power consumption. Therefore, it is essential to design the entire system as a cohesive whole rather than addressing individual components in isolation.

Industrial extraction is used wherever dust, fumes or odours are generated during production. Its task is to capture pollutants directly at the source, protect employee health and ensure safe and reliable technology operation.

Industrial filtration equipment is not a consumer good designed to last for several years. A well-designed filtration unit can reliably serve for 20 to 30 years or even longer with routine maintenance. Throughout its lifespan, it is primarily the filter media and certain operational components that are replaced, rather than the entire system. Therefore, in many cases, it is more cost-effective to modernise existing filters instead of replacing them entirely.

A modern filtration system can significantly reduce electricity consumption and spare parts costs. From a long-term perspective, operating expenses have a far greater impact on the economics of the equipment than its initial purchase price. Therefore, when designing the system, we do not optimise only the investment but primarily the total cost throughout the entire lifecycle of the filtration system.

Customers often ask us whether the filter hoses really last for more than 20,000 operating hours. This is understandable, as many have experience with cartridge filters where the service life of the filter elements is significantly shorter. The long lifespan of the filter hoses and low operating costs are precisely among the main reasons why we opt for fabric filters in a range of applications.

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Industrial extraction

Industrial extraction systems should be designed correctly, not at the lowest cost. Cheap and undersized solutions often result in high pressure losses, low suction power, frequent maintenance interventions, and unnecessarily high electricity consumption. A quality design must be based on actual air volume, dust type, operating mode, filter area, pipework routes, and fan performance. In extraction systems, a simple rule applies: it is better to invest in slightly more expensive but functional equipment than in cheap units that will cause the customer problems for the next 20 years.

The required volume of extracted air can sometimes be obtained from the technology manufacturer, but it is very often the result of experience and the engineer’s technical intuition. Extraction is not an exact science, and two seemingly identical applications may require entirely different airflow rates. Experience gained from dozens of similar projects is usually just as important in the design phase as the calculations themselves.

The performance of the extraction system is not determined by simply adding up all extraction points. Their actual simultaneous operation plays a crucial role. Correctly determining the simultaneity factor enables the design of equipment with optimal sizing, lower investment costs and reduced electrical energy consumption. The aim is not to design the largest possible filter, but rather an installation that will operate reliably throughout its entire service life.

For multiple machines, it is first determined which units can operate simultaneously, and the concurrent airflow rate is designed accordingly. If the system were to extract from all locations at full capacity continuously, it would often be unnecessarily oversized and costly to run. Therefore, we recommend automatic dampers, a fan frequency inverter, and control based on the actual number of open extraction points.

When designing extraction systems for multiple machines, the objective is not simply to sum the maximum performance of all technologies and install the largest possible filter. In most operations, not all machines run simultaneously. We often also take staff numbers into account. For example, if a customer has 10 machines but only two operators, the actual required capacity will be closer to the combined output of the two most powerful machines. Furthermore, modern systems utilise automatic dampers and fan control via variable frequency drives, ensuring extraction occurs only where it is genuinely needed.

The layout of the machines generally does not affect the required extraction capacity, but rather the complexity of the ductwork routes and the pressure required from the fan. Therefore, in our design process we strive for the simplest and shortest possible duct runs. Simpler ducting results in lower pressure loss, reduced energy consumption, and lower capital costs.

If technology permits, centralised extraction is generally more cost-effective than several standalone filtration units. In addition to lower initial investment, it offers easier maintenance, fewer spare parts and reduced operating costs throughout the equipment’s lifespan. Another advantage is a single shared outlet or chimney, which simplifies emission testing for solid fuel combustion (TZL).

Individual extraction for each machine is advisable when the technology has different requirements than the rest of the operation. This typically applies to equipment requiring ATEX certification, laser technologies, sources generating a different type of dust or smoke, higher temperatures, specific vacuum pressure requirements, or other operational modes. In such cases, a standalone filter may be technically safer and more cost-effective than connecting to a central extraction system.

If the customer knows they will be adding more machines in the future, we aim to prepare them for this today. We design the filter with some capacity in reserve, but without unnecessarily investing capital in a large fan that is not yet required. When production expands, you can simply add a second fan or increase performance using a variable frequency drive. It is better to plan ahead than to purchase a new filter five years later.

For central systems, we recommend a minimum performance reserve of 20%. Over the years, we have not yet encountered a customer who did not eventually require additional connections after several years. A modest reserve during the design phase costs significantly less than installing a new filter later on.

Long ductwork is not an issue. It does result in higher pressure loss, but this is accounted for during the design phase and the fan has sufficient pressure capacity. If the system is correctly designed, duct length has virtually no impact on extraction efficiency. An undersized filter or poorly staged ducting will cause far greater problems than an additional 20 metres of duct run.

Hall height is only a significant factor if the filter needs to be installed inside the building. In such cases, we select appropriate dimensions and layout for the filtration unit. Over the years, however, we have not yet encountered a hall where we could not design a functional solution. The issue is rarely the hall’s height; rather, it is finding a solution that makes both technical and economic sense.

Every bend comes at a cost. Not only in terms of pressure loss, but also regarding the lifespan of the pipework. Bends are typically the most stressed component of any system, and with abrasive dusts, wear is greatest here. Therefore, we strive to keep pipeline routes as straight as possible and avoid unnecessary bends.

The best way to reduce pressure losses is not to compromise on the pipework design. The piping should be as short as possible, with minimal unnecessary bends and correctly selected diameters. We also strive to maintain flow velocity as constant as possible, since sharp changes in speed lead to higher pressure losses, increased wear, and a greater risk of dust deposition.

A lower concurrent load means a smaller filter, a smaller fan and a lower investment. There is no reason to design extraction for ten machines when only two are running simultaneously in practice. However, it is important to bear in mind that such a system has its limits. If the extraction is designed for two machines, the customer cannot be surprised five years later that the system struggles when four machines are started at once.

The biggest problem often arises right at the start. If the required capacity of individual machines is underestimated, practically everything else goes wrong: filters, fans, ductwork and energy consumption. Rectifying a poorly designed system costs far more than investing extra time in getting the design right from the outset.

Undersized extraction systems are relatively easy to identify. Dust is present, the fan runs at full capacity continuously, pressure loss is high and filter media have a shorter lifespan. Such a system has no reserve capacity, so any increase in production or filter clogging will immediately result in reduced suction power.

Over-sized suction means the customer once paid for a larger filter than they actually need. If this investment is not an issue for them, it is no tragedy. On the contrary, a larger filtration area usually means lower electrical energy consumption, longer life of the filtering media and lower operating costs. From our perspective, it is better to have a slightly larger filter than a slightly smaller one.

If the air velocity is too low, dust will cease to remain suspended and begin to settle. This leads to pipe blockages, deposit formation, increased pressure losses, and for combustible dusts, compliance issues with ATEX regulations. Therefore, we adhere to the fundamental principle that flow velocity in the ductwork should not fall below 20 m/s. The purpose of the ducting is to transport dust to the filter, not to store it within the system.

Excessively high velocities are also undesirable. They result in increased pressure losses, higher electricity consumption, and greater pipe wear. Elbows suffer the most, as they can literally wear through over time when handling abrasive materials. Therefore, we do not aim for maximum speeds but rather for a velocity that safely transports dust to the filter without unnecessarily increasing operating costs. We recommend maintaining a speed of 20 m/s for most applications and 22–24 m/s when extracting large, heavy particles such as wet sawdust.

We can adapt the filtration unit to practically any space. It is only important not to forget access for maintenance and filter media replacement. In applications involving explosive dusts, it is additionally necessary to allow space for explosion relief. Otherwise, over the years we have yet to encounter a location where we could not fit the filter.

If indoor space within the hall is expensive or simply unavailable, locating the filter outdoors makes great sense. Production space is generally more valuable than a few extra metres of ductwork. Furthermore, for explosive dusts, we consider an outdoor location to be the better solution and, where possible, strive to prioritise it.

If the plant is built in stages, we believe it makes the most sense to construct the extraction system in phases as well. It is preferable to have several independent central systems rather than one massive filtration unit with kilometres of piping. Manufacturing processes evolve over time, and what appears to be the ideal solution today may become a problem in ten years’ time. If the customer requires central waste collection, we address this using separate pneumatic conveying.

We prefer an on-site visit or at least a video of the operation. When we can see the problem with our own eyes, the proposal is significantly simpler. If that isn’t possible, we need to know the extraction requirements for each location, the type of dust, where the filter can be installed, and what the customer intends to do with the collected dust. We don’t expect customers to be extraction experts—that’s exactly why we’re here.

The entire process is simpler than most customers expect. It begins with an enquiry, followed by a technical design and quotation. Once the order is placed, we prepare the construction documentation, manufacture the equipment, arrange installation and electrical works, commission the system, and fine-tune it. Typically, around 9 to 10 weeks elapse from the initial request to the device being operational.

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Industrial sectors

The automotive industry places exceptionally high demands on extraction and filtration systems. Emphasis is placed primarily on reliability, low operating costs, energy efficiency, long service life, and minimal production downtime. Filtration equipment must be capable of continuous operation in three-shift mode while meeting strict requirements for safety and working environment quality.

The engineering industry places high demands on air filtration in terms of reliability, long service life, and the ability to capture fine dust and welding fumes. Low pressure drop, low operating costs, and resistance to sparks, abrasive dust, and continuous operation are also important factors.

The metallurgical industry places exceptionally high demands on extraction equipment, particularly regarding robustness, durability and long service life. Filtration systems must operate reliably in demanding conditions involving high temperatures, abrasive dust, sparks and often continuous operation. Easy maintenance and the ability to handle operational peaks are also crucial.

The foundry industry places exceptional demands on filtration equipment in terms of robustness, resistance to abrasive dust, and the ability to withstand high temperatures and sparks. Extraction systems must operate reliably under continuous duty and endure highly variable operating conditions. Ease of maintenance and long service life are also critical factors.

The energy industry places exceptionally high demands on filtration systems, particularly regarding reliability and long-term continuous operation. A shutdown of the filtration equipment often means a shutdown of the entire power source. Resistance to high temperatures, the presence of unburnt carbon, aggressive flue gas components, and the ability to operate safely across a wide range of operating conditions are also critical.

The wood processing industry places specific demands on dust extraction systems. The primary objective is to ensure reliable transport of sawdust and prevent blockages in pipework, filters, and discharge points. Correct air velocity, smooth internal surfaces, and adequately sized conveying routes are essential. Fire and explosion protection solutions are also standard practice.

The chemical industry places exceptionally high demands on filtration equipment in terms of chemical resistance, safety, and reliability. Stainless steel construction is often required, along with resistance to aggressive substances and solutions compliant with ATEX requirements. System integrity and the long-term durability of materials used against corrosive environments are also crucial.

The pharmaceutical industry places exceptionally high demands on filtration equipment in terms of purity, sealing integrity and safety. It is essential that the equipment can be thoroughly cleaned, constructed from stainless steel, designed to prevent cross-contamination, and, in many cases, compliant with ATEX requirements. Great emphasis is also placed on process validation and traceability of materials used.

The food industry places high demands on extraction systems, particularly regarding hygiene, safety and cleanability. Stainless steel construction is often required, along with the use of materials certified for food contact, and in many applications ATEX-compliant solutions are necessary because flour, sugar, starch or dried milk are classified as explosive dusts.

The rubber industry places specific demands on filtration equipment, particularly regarding resistance to abrasive dust and operational safety. Fine rubber dust and soot can create explosive atmospheres; therefore, ATEX protection is essential in many applications. Resistance to sticky components and long-term reliability of the equipment are also critical factors.

The plastics industry places high demands on extraction systems, particularly regarding safety, reliability, and the ability to transport light and often fibrous particles. Fine plastic dust requires ATEX compliance, whereas coarse plastic swarf from machining is generally less problematic in terms of explosivity. Preventing material build-up in ductwork and ensuring long equipment service life are also crucial.

The paper industry places specific demands on filtration systems, primarily regarding the reliable transport and processing of large volumes of trimmings and paper waste. The system typically includes trim separators, baling presses, and equipment for further material handling. High operational reliability is crucial, as a suction failure can halt the entire production line.

The recycling industry places exceptionally high demands on extraction and filtration systems. The material is often highly variable, frequently containing fibres, light particles, and mixtures of different dusts. Therefore, robust construction, reliable operation, explosion protection (ATEX), and design solutions that minimise the risk of pipe and filter blockages are essential.

Incinerators place exceptionally high demands on filtration systems. Equipment must withstand aggressive chemical components in flue gases, high temperatures, and often the presence of sparks or incomplete combustion products. Consequently, corrosion-resistant materials, stainless steel components, and special filter elements capable of operating reliably under these demanding conditions over the long term are employed. High reliability is also crucial, as a filtration shutdown implies a complete incinerator outage.

Biomass boilers place high demands on filtration equipment, particularly in terms of reliability, resistance to high temperatures, and the ability to safely handle sparks and unburnt residues. The chemical composition of flue gases and protection against condensation also play a crucial role. The filtration system must be designed for continuous operation and long service life.

Cement plants represent some of the most demanding applications for flue gas filtration. Filtration systems in this sector must withstand very high dust loads, elevated operating temperatures and highly abrasive environments. Robust construction, long service life and the ability to operate reliably under continuous conditions are essential.

Packaging plants place high demands on filtration systems, particularly in terms of robustness, thermal insulation, and protection against heavy dust loading. Due to the presence of coarse particles and high temperatures, pre-separation chambers are often employed to reduce the load on filter elements and extend their service life. Protection against condensation and long-term equipment reliability are also crucial factors.

Electroplating plants place exceptional demands on extraction systems, particularly regarding chemical resistance and corrosion protection. Due to aggressive vapours, plastic pipework and chemically resistant components are frequently used. Great emphasis is also placed on energy efficiency and heat recovery, as the volume of air extracted is often substantial.

Battery manufacturing places exceptionally high demands on filtration equipment in terms of chemical resistance, safety and reliability. Monitoring residual dust loss is also crucial, as fine powders containing active materials are highly valuable; their escape can affect both production quality and operational safety. In many applications, ATEX-compliant solutions are standard practice.

The production and processing of aluminium impose exceptionally high demands on extraction systems, particularly in terms of safety. Fine aluminium dust is highly explosive, making ATEX-compliant design an essential component of the solution. Preventing the build-up of deposits, minimising ignition sources, and, in many cases, sorption to reduce moisture and oily components are also critical for ensuring safe operation.

Steel production places exceptionally high demands on filtration systems, particularly in terms of resistance to high temperatures, robustness and long-term reliability. Filtration equipment must handle high dust concentrations, sparks, abrasive particles and continuous operation. The primary requirement is a long service life with minimal production downtime.

Spray booths impose specific requirements on extraction systems, particularly regarding ATEX compliance, resistance to clogging, and low operating costs. Filtration units must reliably capture sticky particles and aerosols, enable effective regeneration, and ensure a long service life for filter media. Great emphasis is also placed on the consumption of filter elements and the cost of their replacement.

Logistics centres and fuel storage facilities impose specific requirements on dust extraction systems, particularly regarding ATEX compliance, humidity control, and condensation prevention. Adequate air exchange within the space is also crucial, along with high-quality thermal insulation of the equipment to prevent condensate formation and subsequent operational issues.

Facilities equipped with robotic lines place exceptional demands on extraction systems, particularly regarding reliability and continuous operation. Robotic lines often operate 24 hours a day, seven days a week, meaning any failure in the extraction system could result in downtime for an entire production cell or line. Low maintenance requirements and long equipment lifespan are also crucial factors.

Facilities operating continuously place exceptional demands on filtration systems, particularly in terms of reliability, robustness and operational reserve. The filter must not be the weakest link in the technology, as its downtime often means halting the entire production process. Therefore, these systems are frequently designed with a certain margin of safety, emphasising long service life and straightforward maintenance.

High-dust operations place significant demands on filtration equipment, particularly in terms of reliability and the capacity to handle large volumes of captured material. It is crucial that the design of discharge points and conveying systems prevents bridging and dust accumulation. The filtration system must be robust and capable of sustained operation under high load conditions.

Facilities dealing with abrasive dust place high demands on filtration equipment, particularly in terms of robustness and wear resistance. Abrasive particles can cause intense abrasion to pipework, bends, hoppers, and other components of the technology. Therefore, it is important to select suitable materials and design solutions that ensure a long service life for the equipment.

Facilities dealing with sticky dust place specific demands on filtration equipment, primarily regarding the prevention of material buildup. Adequate airflow velocity in the ductwork, low filtration velocity, and often the dosing of sorbents—which reduce the stickiness of the dust and improve filter regeneration—are crucial. The aim is to prevent the clogging of filter elements and ensure long-term stable operation.

Facilities with high humidity impose specific requirements on filtration equipment, particularly regarding protection against condensation. The foundation is high-quality thermal insulation that prevents the temperature from dropping below the dew point. Another highly effective measure involves dosing sorbents, such as zeolite, and heating hoppers or other parts of the process in critical areas.

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Lifespan of filter media

We primarily use microporous textile filter media, specifically PES MP and PES MPA. For explosive dusts, we employ antistatic versions, while for hot flue gases, we select media based on temperature—such as PPS, aramid, PTFE, ceramic, or stainless steel filter elements. We do not choose materials from a catalogue; instead, our selection is driven by the specific characteristics of the dust, temperature, humidity, and flue gas chemistry. With standard fabric filters, we focus on low pressure drop, long service life, and stable residual emissions typically in the range of single-digit mg/m³ or lower.

At our textile filter bags, we typically assume a minimum service life of 20,000 operating hours, provided the filter is correctly designed and operated. This represents a significant difference compared to cartridge filters, where service lives in heavier-duty applications often range only between 2,000 and 4,000 hours. The extended lifespan results from a smooth surface without creases, appropriate filtration velocity, low pressure drops, effective regeneration, and the selection of media suited to the specific dust type.

The service life of filter bags is most significantly influenced by filtration velocity, dust type and abrasiveness, moisture, temperature, the chemical composition of the gas stream, and the settings for pulse-jet regeneration. If a filter is undersized, the media becomes overloaded, clogged, and mechanically damaged during regeneration. A properly designed fabric filter operates with an appropriate filtration velocity, a stable dust cake, and consistent pressure drop.

Filter bags should be replaced when the pressure drop remains high even after regeneration, emissions downstream of the filter increase, or the medium is mechanically damaged. A practical indicator is also rising fan power consumption, as every additional 100 Pa at constant flow results in higher electricity usage. Replacing the medium is a one-off cost, whereas operating with a clogged filter increases expenses every day and hour.

The service life of filter bags can be extended in applications involving oily dust or slight moisture by installing a sorbent dosing station. The sorbent ensures the drying of the filter media, improves the reusability of the filter and reduces pressure drop. To protect against mechanical damage, it is advisable to have an integrated pre-separation chamber for coarse contaminants within the filter.

With cartridge filters in industrial plants, we often see service lives of around 2,000 to 4,000 operating hours; these can be longer for grinding applications, but significantly shorter for welding or sticky dusts from CNC burning. Although the filter cartridge has a large filtration surface area, this is achieved by pleating the filter media into an accordion shape with very narrow gaps. Dust settles precisely in these gaps and cannot be removed even by pressure air regeneration. Therefore, we recommend cartridge filters mainly for smaller, cleaner, and less dusty applications, rather than as a universal solution for heavy industry. They are certainly not suitable for 24/7 operation.

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Filter media and filter hoses

The filter medium is the core component of the filter where dust particles are captured. It can consist of a fabric tube, a filter cartridge, a pleated element, or another type of filter insert. The filter medium itself does not function as a sieve; instead, a dust cake forms on its surface, which significantly contributes to the overall efficiency of the dust extraction process.

The primary function of the filter media is to separate dust particles from the flowing air. Dust accumulates on the surface of the filter media, while the cleaned air continues through to the fan or into the surrounding environment. The quality of the filter media has a significant impact on the efficiency of the dedusting process, pressure drop, and the overall lifespan of the filtration equipment.

Filter media are selected based on temperature, the chemical composition of the gases, and required durability. Textile filter media are most commonly used; these can be antistatic, oleophobic, hydrophobic, or heat-resistant. For high-temperature applications, ceramic filter elements are available with an operating temperature of up to 400 °C. For the most demanding environments, microporous stainless steel media are employed, enabling flue gas filtration at temperatures around 500 °C.

The correct choice of filter media should not be left to the user but to the supplier of the filtration equipment. The supplier must understand the nature of the dust, temperature, humidity, chemical composition and operating conditions, and on this basis select a medium that guarantees the specified service life and reliable performance of the filter. The use of unsuitable media can lead to rapid clogging, high pressure drop or premature wear.

The selection of filter media is primarily influenced by the operating temperature, the chemical composition of the extracted gas, and the nature of the dust. The presence of sparks, hot particles, or unburnt residues is also critical, as these can damage standard textile media. In certain applications, it is necessary to consider moisture levels, abrasiveness, ATEX requirements, or antistatic properties. Choosing the correct filter media is essential for achieving the desired service life and reliability of the filter.

The filter bag is the most common type of filtration media used in industrial filters. It consists of a microporous textile sewn into a cylindrical or flat tube shape, often referred to as a filter bag. Dust is captured on its surface, while cleaned air passes through the textile into the clean chamber of the filter. The shape and design of the bag are selected according to the specific application and required filtration area.

The filter cartridge operates by capturing dust particles on its outer surface, while the cleaned air flows through the filtering medium into the clean chamber of the filter. Over time, a dust cake forms on the surface, which is removed at regular intervals by a short pulse of compressed air. This reverse-flow impulse dislodges the dust cake, allowing it to fall into the filter hopper.

Filter cartridges are manufactured from microporous textiles that allow air to pass through while reliably capturing even very fine dust particles. The material used is selected based on temperature, the chemical composition of the gases, and other operating conditions. Available filter media include polyester, aramid, PPS or glass fibre, which can be supplemented with an antistatic treatment or a PTFE membrane to achieve maximum filtration efficiency.

The different types of filter media vary primarily in their properties and areas of application. Key parameters include operating temperature, chemical resistance, and special treatments such as antistatic finishes, oleophobic or hydrophobic coatings. These characteristics determine the suitability of a given filter medium for specific applications and its expected service life.

Temperature has a fundamental impact on the choice of filter media. For standard applications, polyester (PES) media with an operating temperature of up to approximately 150 °C are most commonly used. For higher temperatures up to 200 °C, aramid media are suitable. If the temperature exceeds the capabilities of textile materials, ceramic filter elements or microporous stainless steel media are employed, allowing filtration at temperatures around 500 °C. The correct choice of media is crucial for the lifespan and reliability of the entire filtration system.

Humidity has some influence on the choice of filter media, but preventing condensation is even more important. The mere presence of water vapour usually does not pose a problem as long as flue gases or air are kept above the dew point. In cases where condensation is likely, we recommend dosing a sorbent, such as ground zeolite, which binds moisture and simultaneously improves the regeneration of the filter media.

The chemical composition of the gases has a fundamental impact on the choice of filter media. The medium must be resistant to substances present in the extracted air stream to prevent chemical degradation or loss of mechanical properties. When filtering aggressive gases, it is therefore essential to select a filter medium that can withstand specific chemical components over the long term and ensure the required service life of the filter.

Abrasive dust has surprisingly little impact on the choice of filter media. We aim to remove coarse and heavy particles in the pre-separation chamber, so only fine dust reaches the actual filter medium. Abrasiveness is far more significant when designing pipework, bends, and other system components than when selecting the filter media itself.

Grease aerosols usually have little impact on the choice of filter media. It is more important to prevent clogging of the filter medium. If grease content is higher, we recommend dosing a sorbent that binds the grease and improves filter regeneration. With proper system design and the use of sorption, grease aerosols do not pose a significant problem for the filter medium.

The antistatic filter medium is always suitable for applications with ATEX requirements. Its role is to dissipate the electrostatic charge generated during dust flow and prevent spark formation on the surface of the filter medium. This reduces the risk of igniting an explosive atmosphere and increases the safety of the entire filtration unit. Consequently, an antistatic design is a standard requirement when handling combustible dusts.

Micro-porous polyester filter media are most commonly used for welding extraction. However, it is important to note that maximum filtration efficiency is not achieved with a new, clean hose, but only after a dust cake has formed on its surface. The actual filtration then takes place via the so-called 'dust-on-dust' principle, where the layer of captured dust acts as a highly effective filter medium for subsequent fine welding fume particles.

For grinding dust extraction, microporous polyester filter media are most commonly used. However, the smooth surface of the filter medium is more important than the material itself, as it allows dust to shed easily during regeneration. For this reason, cartridge filters with deep pleats are not ideal for grinding applications, as dust can accumulate there and impair regeneration. Smooth filter hoses or flat bags typically ensure more stable operation and a longer service life.

For the wood-processing industry, microporous antistatic filter media are most commonly used. The antistatic design ensures safe dissipation of the electrostatic charge generated by the flow of sawdust and dust, reducing the risk of spark formation. Simultaneously, the microporous surface enables high filtration efficiency and good regeneration, contributing to a long service life for the filter hoses.

For flue gas filtration, the choice of filter media is primarily driven by operating temperature. Meta-aramid filter media are most commonly used for temperatures up to approximately 200 °C. For higher temperatures, ceramic filter candles or microporous stainless steel filter elements are employed, enabling reliable filtration at temperatures around 500 °C. The correct selection of media must take into account not only the temperature but also the chemical composition of the flue gas, the presence of sparks, and any incomplete combustion.

For high-temperature applications, ceramic filter media and microporous stainless steel filter cartridges are used. Ceramic filter candles are suitable for operations involving high temperatures and the presence of sparks or unburnt fuel. Microporous stainless steel media enable filtration at temperatures up to approximately 500 °C and exhibit high mechanical and chemical resistance. Both types of media are designed for the most demanding applications where conventional textile media cannot be used.

For humid environments, microporous polyester (PES MP) filter media are most commonly used. However, the choice of media itself is less critical than preventing condensation and filter blinding. Therefore, in problematic applications, sorbent dosing—such as ground zeolite—is often employed to bind moisture and improve the regeneration of the filter media.

With sticky dusts, the type of filter media is less critical than ensuring the correct loading of the filtration area. A lower filtration rate allows for the formation of a thinner dust cake and improves filter regeneration. In many cases, sorbent dosing is also employed to modify dust properties and prevent blinding of the filter media. Here, proper filter design is more important than the choice of specific material.

The most common cause of damage to filter bags is their natural wear and tear and material fatigue. Over time, the fabric loses its mechanical properties, pores enlarge, and the filtering medium begins to allow more dust through. The service life of filter bags is also influenced by the frequency of regeneration, operating temperature, chemical composition of the gases, and any potential mechanical stress.

Damaged filter hoses most commonly manifest as increased dust emissions at the filter outlet. Typical signs include visible dust from the chimney, dust accumulation on the clean side of the filter, or a sudden drop in pressure loss. In some cases, this can also lead to sudden fan imbalance, as escaping dust begins to deposit on the impeller. It is precisely the combination of these symptoms that usually indicates damage to the filter medium.

An inappropriately selected filter medium most often manifests as non-standard pressure drop and reduced service life. Contact with water or oil can cause the filter material to swell and become clogged. Conversely, an unsuitable structure or excessively loose fabric may lead to increased emissions and dust breakthrough. Issues may also arise from impaired regeneration, a rapid rise in pressure drop, or premature mechanical wear of the filter hoses.

The cost of the filter medium is only a small part of the total expenses. Its lifespan and pressure drop are what really matter. If the media clogs quickly, it needs frequent replacement, and the fan consumes more electricity. Cartridge filters are a typical example: the cartridges themselves are expensive, and they need replacing 4 to 8 times more often than bag filters. Therefore, it pays to look at the cost per year of operation rather than the price of a single filter element.

Selecting the right filter media is crucial to ensure that the filter performs its function reliably over the long term. However, the filter media represents only one part of the overall system. Equally important are a properly designed filtration area, media loading, regeneration, air flow, and operating conditions. The aim is for the filter to operate reliably while remaining virtually unnoticed by the user.

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Comparison of hose and cartridge filters

For most industrial applications, we consider fabric bag filters to be more cost-effective in operation than cartridge filters. They feature a smooth filtration surface, handle higher dust loads better, can be effectively regenerated, and typically achieve a service life of around 20,000 operating hours. Although cartridge filters may have a lower initial cost, this advantage is often offset in demanding applications by the need for frequent cartridge replacements, higher pressure drops, and downtime required for maintenance.

Cartridge filters make sense for lower power outputs, light dust loads, and applications where compact equipment size is important. They are typically used in smaller workstations, simple welding tasks, light grinding, or environments where high dust levels and long continuous operation are not expected. When it comes to central extraction systems, heavy dust loads, or the need for low maintenance costs, a fabric bag filter makes more sense.

For most industrial applications, we consider fabric bag filters to be more cost-effective in operation than cartridge filters. They offer a larger active filtration area, handle higher dust loads better, can be effectively regenerated, and typically achieve a service life of around 20,000 operating hours. Although cartridge filters may have a lower initial cost, this advantage is often offset in demanding applications by the costs associated with cartridge replacements, higher pressure drops, and unplanned downtime.

Yes, in many applications we consider bag filters to be a more cost-effective solution than pleated filters. Pleated elements have a long service life of approximately 40,000 operating hours, but their higher pressure drop can result in unnecessarily high energy costs. A difference of around 1,000 Pa per fan is not trivial; for industrial extraction systems, this often translates to tens or even hundreds of thousands of pounds annually. Therefore, it is essential to evaluate not only the price and lifespan of the filter media but primarily the total operating costs of the equipment, including electrical energy consumption.

The lowest total operating costs are typically achieved with a well-designed textile filter: longer media life, lower pressure drop and fewer service interventions. A cartridge filter may have a lower initial purchase price, but in dusty operations the costs shift to frequent cartridge replacements. Lamellar or sintered elements can last for a long time, but if they operate at higher pressure drops, the customer pays the difference in fan power and electricity. We recommend textile bag filters as the most economical option.

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Design and implementation

Implementation begins with the technical specification, calculation of flow rates and pressure losses, and the design of filters, fans, ductwork, and safety components. We then prepare a 3D model and manufacturing documentation, manufacture the equipment, deliver it, install it, and commission it. During commissioning, we check flow rates, pressure loss, regeneration, fan operation, and control functions.

The design of the filtration system is a comprehensive process that begins with an operational analysis to determine the type and volume of dust, temperatures, humidity levels, and potential risks, including ATEX requirements. This is followed by defining the required extraction capacity and system concept; subsequently, the filter area is sized, the filter media type is selected, ductwork layouts are designed taking into account flow velocities and pressure losses, and a suitable fan and control method are specified. Throughout this process, energy consumption, noise levels, safety, and air recirculation options are also addressed. The result is a technical design that ensures not only compliance with emission and hygiene limits but also long-term stable, safe, and economically efficient operation.

To prepare an offer for filtration equipment, it is essential to have a thorough understanding of the process or problem at hand—specifically, what is being extracted, where the emission originates, and what the operating conditions are. Furthermore, the type of dust or medium, including its properties (such as abrasiveness, stickiness, temperature, and ATEX risk), is crucial, as this significantly influences the choice of filtration technology. Other important factors include required extraction capacities and air balance, the location of the filtration unit and spatial constraints, as well as requirements for air recirculation, noise levels, energy consumption, and any applicable legislative limits. The more precise these inputs are, the more accurate and economically optimised the final offer can be.

To design an extraction system, the primary requirements are details regarding the operational process: specifically, which technologies and machines require extraction, where emissions originate, and what the production mode entails. Furthermore, it is essential to define the type of medium being extracted, including its properties such as dustiness, abrasiveness, stickiness, moisture content, temperature, and any potential toxicity or ATEX risk. Key considerations also include the required extraction capacities, available space for equipment placement, pipeline lengths and routes, and the number and type of extraction points. Supporting documentation must also address requirements related to energy efficiency, power regulation, noise levels, air recirculation (if applicable), and legislative limits, as all these factors significantly influence the final system design.

A personal site visit is not always mandatory, but in most cases it is highly recommended as it significantly refines the design of the extraction system. On-site inspections allow you to verify actual operating conditions, observe equipment layout, assess airflow patterns, and crucially determine where extraction points are most effective and what volume of air is genuinely required.

In practice, a preliminary design can be produced without a visit; however, for more complex facilities, missing details may significantly impact system performance, pressure drop, and overall functionality. Therefore, an on-site inspection is often decisive for correct sizing and the economic viability of the entire solution.

Technical consultations typically take the form of phone calls or online meetings, where the customer describes their operations, issues, or objectives, and the supplier then guides them through targeted questions to clarify all essential parameters. This process gradually gathers information on technology, type and volume of extracted media, operating conditions, layout solutions, as well as performance, control, or regulatory requirements. The aim is to quickly understand the situation and propose an appropriate technical solution or next steps, such as a site visit, measurement, or preparation of a quotation.

The on-site assessment involves the technician visiting your facility directly to conduct a thorough inspection of all relevant technical components. They will measure dust or emission sources, distances between individual machines, diameters and routes for potential pipework, while simultaneously evaluating spatial requirements for installing the filtration unit, fan, and other components. This process also includes assessing the most suitable routing for pipework networks, taking into account minimal pressure losses, maintenance access, and operational safety. Based on these findings, the system design is refined to provide an accurate technical and commercial proposal.

Project design typically follows the site survey and is often carried out by the same engineer or designer who visited the location, as they have the best understanding of the actual conditions. In this phase, data are converted into a technical design, most commonly in a 3D model, where pipe routes, the position of the filtration unit, fan, and all other components are precisely defined. The output includes drawings, technical descriptions, calculations (e.g., flow rates and pressure losses), and often specifications for materials and components. The result is complete project documentation.

The design of filtration equipment typically takes several days, provided all necessary documentation is available and the project is neither complex nor atypical. For standard applications, basic design and sizing can be completed quickly as they are based on proven principles and standardised solutions. However, if additional site surveys, consultations or detailed calculations (e.g., ATEX compliance, heat recovery, complex pipework routes) are required, the design process may take longer. In practice, therefore, the speed of the design depends directly on the quality of the input information and the complexity of the operation.

The production of smaller and medium-sized filtration units with capacities up to approximately 30,000 m³/h typically takes around 8–10 weeks from project approval and order placement. This timeframe includes the manufacturing of the steel structure, surface treatment, assembly of filter elements and fans, as well as preparation for dispatch. For more complex or non-standard solutions, production times may be extended, particularly when special materials, ATEX-certified versions, or non-standard components are used.

The delivery of the filtration unit after production is completed depends primarily on logistics and the distance to the installation site, as transport itself is the final step before assembly. For standard orders within the Czech Republic and neighbouring countries, delivery typically takes a few days; for more remote locations or oversized shipments, it may take longer due to transport planning, permits, and handling. The overall timeframe is therefore not fixed but is determined mainly by transport availability, equipment type, and the distance from the manufacturing plant to the installation site.

The installation of filtration equipment for smaller and moderately complex units with capacities up to approximately 30,000 m³/h typically takes around five to ten days, depending on site readiness and the complexity of the ductwork. The installation process involves mounting the filtration unit, fan, and supporting structure, connecting the pipework, installing the electrical components and control system, and subsequently linking all technological subsystems. A crucial aspect is also the assembly and leak testing of the ductwork, as well as wiring for regeneration and safety features. Upon completion of the installation, the system undergoes commissioning, initial adjustment, and functional tests to verify correct extraction performance prior to handover for operation.

Yes, in most cases, the installation of filtration equipment can be carried out while the plant is operational, which is standard practice to minimise production downtime. The process is conducted in stages: first, civil and mechanical works are prepared; subsequently, the technology is gradually connected and switched over so that existing extraction continues for as long as possible without interruption. Short downtimes are typically only required during the final piping reconnection and system commissioning, but with adequate preparation, these are very brief and often last only a few hours. Effective coordination with operations, proper planning, and pre-assembly of individual components are essential to ensure installation has minimal impact on production.

The production downtime during the installation of the filtration system can be minimised primarily through careful planning of the entire implementation and close coordination between the site manager and the customer’s operations team, ensuring that each step is precisely timed to align with the actual operation of the technology. It is important to pre-assemble as much of the equipment as possible while the plant remains operational, define a clear tie-in window, and provide a detailed work schedule that limits downtime to only what is essential for piping connections and commissioning. The preparation of the site, availability of all components, and rapid response during final connection also play a significant role, collectively enabling installation with minimal impact on production.

Commissioning takes place after installation is completed and involves the gradual activation of all system components. First, electrical wiring, safety devices, and basic device functions are inspected. The system is then started in test mode to verify the correct operation of individual components such as the fan, regeneration unit, and control system. Subsequently, operating parameters are adjusted, including air flow rate, pressure drop, regeneration frequency, and fan speed. The entire system is tuned to match design specifications and ensure stable performance under varying loads. Finally, functional tests, safety device checks, and operator training are carried out before the equipment is handed over for permanent operation.

Operator training takes place on-site at the installed equipment and is conducted by the supplier’s technician or specialist. Initially, the operator is introduced to the entire system, its functions, and basic operating modes. Subsequently, they are instructed on controlling the control system, setting fundamental parameters such as power regulation, filter regeneration, and alarm states. A crucial component of the training also includes a practical demonstration of routine operations and responses to typical scenarios. Finally, operators receive training in regular checks, including monitoring pressure drop, visual inspections of the equipment, and basic maintenance, ensuring they can operate the system safely and efficiently.

Upon project completion, a comprehensive documentation package is handed over to confirm the correct execution, functionality, and safety of the entire filtration system. The core consists of technical equipment documentation, including drawings and specifications for individual components. Additionally, the CE Declaration of Conformity and operation and maintenance manuals are provided. This also includes inspection reports, particularly electrical inspections, along with any others relevant to the scope of supply, and a commissioning report confirming that the designed parameters have been achieved. The package is completed by a handover protocol and operator training records, as well as further test and measurement reports if included in the project scope.

The handover of the equipment takes place after installation is completed, commissioning has been carried out, documentation has been handed over and operators have received training. During this phase, we jointly verify with the investor or operator that the equipment complies with the project documentation and meets the agreed technical specifications. This also includes verifying performance under real operating conditions, checking safety components and key operational parameters such as extraction capacity and pressure drop. If everything is in order, the equipment is formally handed over by signing a handover protocol, at which point it enters normal operation and responsibility for its operation and maintenance passes to the operator.

The warranty test is carried out after the equipment has been commissioned, with the aim of verifying that the filtration system achieves the contractually guaranteed parameters. Typically, key values such as suction power, pressure drop, energy consumption, filtration efficiency or noise levels are measured and compared against the project documentation and the supplier’s guaranteed technical data.

Measurements are taken under defined operating conditions to ensure that results are comparable and repeatable. If the equipment meets all specified parameters, the warranty test is concluded successfully, confirming correct system operation. In the event of deviations, adjustments or fine-tuning of the equipment are carried out and the test is repeated.

Device optimisation after startup takes place during the system balancing phase, where all operational parameters are fine-tuned to ensure extraction operates as efficiently as possible while consuming minimal energy. The engineer gradually adjusts the dampers on individual duct branches to achieve the correct flow distribution and modifies the vacuum in the system so that it aligns with the design specifications. Simultaneously, the operation of the fan, filter regeneration, and the control system’s response to real-world conditions are optimised.

The aim is to ensure stable extraction performance, low pressure loss, and uniform extraction across all workstations. During optimisation, operational values are also checked under various load modes, and the system behaviour is fine-tuned to operate efficiently, safely, and without fluctuations in performance.

Yes, the filtration and extraction system project can very often be implemented in stages; in industrial practice, this is actually a common approach. Phasing allows for spreading the investment over time while simultaneously minimising the impact on production, as individual parts of the system can be gradually connected to existing technology. Typically, one starts with the main filtration unit and the most critical extraction points, followed by the expansion of the pipework network, additional control systems, or further extraction branches. A properly designed phased approach must account for future expansion so that the entire system remains hydraulically and energetically balanced, allowing it to be extended without difficulty and without requiring major modifications.

Preparing the hall for the installation of filtration equipment may not be complex, but it certainly requires careful planning, as appropriate structural and technical infrastructure significantly impacts both the installation process and subsequent operation. The foundation lies in a suitable concrete base or structure for the filter and fan, designed to support both static and dynamic loads. It is also essential to provide construction openings for pipework and cabling to minimise additional building works. Preparation should include an electrical connection to power the entire system and a compressed air supply for filter regeneration, ideally with sufficient capacity and air quality. Ensuring access routes for installation and maintenance, as well as space for handling individual components, is equally important. Thorough preparation of the hall significantly reduces installation time and lowers the risk of complications during setup.

The most common construction modifications involved in installing filtration equipment are primarily a concrete slab or foundation to support the filter and fan, which must bear the weight and operational vibrations of the plant. Additionally, structural penetrations through walls or roofs are typically required for ductwork, cable routes, and the extraction of clean or exhaust air. In some cases, internal adjustments to the hall layout may also be necessary, such as ensuring sufficient space for installation, service access, or the routing of ventilation systems.

Electrical connection requirements are always defined in the project documentation, which specifies the total power consumption of the equipment, the method of connection, cable type, and protection requirements on the investor’s side. The project also includes specifications for supply voltage, frequency, and any requirements for power reserve to accommodate future expansion. Typically, the investor is responsible for providing the supply cable and routing it to the installation site, ensuring that a connection point is ready for the final technology connection by the supplier.

Air supply requirements are always specified in the project documentation as they directly impact filter regeneration performance. Typically, consumption is defined in Nm³/h, operating pressure at approximately 6 bar, and required air quality including the dew point, which is selected based on equipment location. For outdoor installations, a dew point of around −40 °C is standard to prevent condensate freezing during winter, whereas for indoor installations, a dew point of around +5 °C is usually sufficient. The requirements also specify oil-free and particle-free air quality, as compressed air purity significantly affects the reliability and lifespan of pulse valves and the entire regeneration system.

Foundation and structural support requirements are always defined in the project documentation according to the specific type of filtration equipment. Typically, the size of the concrete area, the layout of individual foundations, and the maximum load on the base or foundation structure are specified. The design also includes requirements for levelness, ground bearing capacity, and, where necessary, vibration damping, particularly for fans or larger filtration units. Properly executed foundations are crucial for equipment stability, long-term durability, and trouble-free operation without unwanted vibrations or structural deformation.

Coordination with other trades during implementation is primarily conducted on a personal level, through ongoing communication, negotiation, and joint planning of each construction step. In practice, this means aligning the installation of the extraction system with electricians, the construction company, HVAC specialists, and the customer’s production technology to ensure that all components fit together seamlessly and avoid unnecessary downtime. It is essential to have a clear work schedule, regular site inspection days, and swift resolution of changes on-site, as most issues are addressed operationally based on the current stage of installation. The aim is for all trades to function as one cohesive unit, resulting in smooth implementation without unnecessary conflicts or delays.

Extending an existing system typically begins with a site survey to assess the current state of the technology, performance reserves, and options for connecting new extraction points. A design proposal is then prepared, ensuring seamless integration with the existing system in terms of hydraulics and energy efficiency, thereby preventing fan overload or increased pressure losses. The proposal also includes an evaluation of control systems, pipework distribution, and any necessary modernisation of key components to ensure reliable and efficient operation without negatively impacting current processes.

The modernisation of an older filtration plant is carried out in stages, always beginning with a site inspection and assessment of the existing system. This involves evaluating the technical condition of the structure, filter components, fan, and ductwork. A design proposal for the modernisation follows, which may include new filter installations, adjustments to regeneration processes, enhanced performance control, or optimised pipework to reduce pressure losses and improve energy efficiency. New components are then manufactured and an installation plan prepared to ensure minimal downtime. The actual installation involves replacing or adding equipment parts, followed by commissioning, system adjustment, and handover into operation, ensuring that the modernised plant delivers superior operational performance compared to the original solution.

Yes, upgrading equipment from another manufacturer is possible in most cases, as industrial filtration systems operate on the same principles. However, a thorough assessment of the existing condition, precise scoping, and clear definition of technical requirements and investor expectations are always essential. Each system features unique design configurations, wear levels, and operational margins; therefore, the filter housing, fan, ductwork, and control system must first be evaluated before proposing a specific modernisation scope to achieve the desired improvements in performance, energy efficiency, and operational reliability.

Replacing an old filtration unit with a new one typically involves removing the existing system and installing the new equipment in the same or modified location. In many cases, the existing pipework can be retained if its condition, dimensions, and pressure losses are suitable for the new solution, significantly reducing installation time and overall costs. The process also includes rewiring, commissioning the new filter, and adjusting it to meet the required performance levels and operating conditions.

Yes, retaining the existing ductwork is possible in most cases and is frequently implemented in practice, as it significantly reduces costs and implementation time. However, this requires that the ducts are in good technical condition, have appropriate dimensions and flow velocities, and do not cause excessive pressure losses that would restrict the performance of the new filtration unit. Therefore, an inspection and assessment of the existing ductwork system is always carried out beforehand to ensure compatibility with the new solution and prevent any reduction in its efficiency.

The relocation of the filtration unit is carried out according to its size, weight and site accessibility. Smaller units are typically handled as a whole using a forklift or crane, provided space permits. For larger filters, partial dismantling into smaller assemblies is often performed to ensure safe disassembly, transport and subsequent reinstallation at the new location. It is essential to consider floor load capacity, access routes and handling safety to prevent damage to the equipment or building structure.

The most common issues encountered during project implementation stem from scope changes made during construction, such as clients requesting additional extraction points, altering the layout, or increasing system capacity. These modifications often impact fan sizing, filter area, pressure losses, and ductwork distribution, potentially necessitating revisions to parts of the design or supplementary equipment. Other frequent complications include inadequately prepared sites, clashes with other trades, missing penetrations, or changes to installation schedules, all of which can extend the implementation timeline. The key to minimising such issues lies in providing precise specifications at the outset and managing changes systematically throughout execution.

Errors during the installation of filtration equipment can be prevented primarily through careful planning of the entire implementation. The foundation lies in high-quality design documentation that precisely defines the technology’s location, pipework routes, electrical connections, and requirements for site readiness. Coordination between different trades is also crucial to avoid clashes on-site and ensure all components integrate seamlessly. Personal attention and verification of the actual conditions prior to installation play a significant role, as they reveal any discrepancies against the design. The installation itself should follow a clear schedule with ongoing step-by-step checks, significantly reducing the risk of errors and unnecessary adjustments on-site.

A smooth transition to the new extraction system is typically implemented in stages to minimise disruption to production. First, the filtration unit—including the fan, controls, and central ductwork—is fully installed and commissioned so that the new system operates reliably and stably. Subsequently, individual extraction points are gradually switched from the old system to the new one within a short planned window, ideally section by section or zone by zone. Once connected, the system is activated immediately and the controls fine-tuned to ensure optimal performance and balanced extraction. This approach minimises downtime and ensures a seamless transition without significant impact on production.

Warranty service commences upon commissioning. During the warranty period, which begins once the equipment is handed over for operation, all repairs and defect rectifications attributable to the supplier are covered by them. This period primarily addresses equipment failures, material defects, or technological errors not caused by improper operation or maintenance. Conversely, routine servicing, preventive inspections, and standard upkeep generally fall outside the scope of the warranty and are borne by the operator, unless otherwise agreed contractually. The objective of warranty service is to ensure reliable equipment performance and timely resolution of any latent defects without incurring additional costs for the investor.

The standard warranty period for filtration equipment is typically 24 months from commissioning, unless otherwise specified in the contract. In some cases, this may vary depending on the project type, scope of supply, or individual contractual terms; however, a two-year warranty is the most common practice within the industry. During this period, the supplier is responsible for rectifying defects arising from the design, manufacture, or installation of the equipment.

Post-warranty service typically follows three stages. First, the equipment’s condition is assessed through diagnostics, evaluating filter performance, fan operation, regeneration efficiency, pressure losses, and overall technical status. Based on this inspection, a repair or upgrade proposal is prepared, including recommendations for replacing worn components and an estimated cost.

Once the customer approves the quotation, the service intervention is scheduled, and a technician visits the site to carry out repairs, replace parts, or adjust the system. The equipment is then tested, its functionality verified, and it is usually returned to operation with a record of the completed service.

Long-term trouble-free operation of the equipment is ensured primarily through regular maintenance, which allows wear and emerging faults to be identified in time before they cause breakdowns or downtime. It is also important to continuously monitor key operational parameters, particularly pressure losses, regeneration function, fan performance, and system sealing. Preventive servicing by the supplier, typically once a year, plays a significant role as well, ensuring detailed inspection and adjustment of the entire unit. This combination of measures significantly reduces the risk of unplanned downtime and extends the lifespan of the overall technology.

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Energy efficiency

Energy consumption of the extraction system can be reduced primarily through correct power regulation. The foundation lies in a frequency converter on the fan, automatic dampers at individual workstations, and control based on actual extraction demand. Equally important is low pressure loss across the entire system—achieved through correctly designed ducting, filters, and fans.

The biggest energy consumer in extraction systems is the filter. This is primarily due to the pressure drop across the filter medium and the dust cake that forms on it. Additional losses occur in pipework, fittings, and poorly designed transitions. Therefore, it pays to pay close attention to low pressure drop already during the design phase of the equipment. For example, pleated filters typically have a pressure drop up to 1000 Pa higher than conventional bag or cartridge filters, which significantly impacts electrical energy consumption and makes them an economically unfavourable solution in the long term.

The design of the extraction system has a significant impact on its lifetime energy consumption. Key factors include filter size, filtration area, type of filter media and overall system pressure drop. A correctly designed unit can save many times more over its lifespan than the difference in purchase price.

Pressure drop has a significant and direct impact on the electrical energy consumption of the extraction system, as the fan must constantly overcome it; therefore, higher pressure drop results in greater power input and operating costs. With bag filters, the pressure drop is typically lower and more stable over time due to the large filtration area, uniform airflow, and consistent dust cake formation, leading to more energy-efficient operation. In contrast, sintered lamellar filters have a smaller surface area and higher flow resistance even with clean media due to their construction, which typically results in a higher pressure drop (often around 1000 Pa higher) and consequently significantly greater fan energy consumption throughout the equipment's lifespan.

Filter size has a direct impact on operating costs. A larger filtration area and greater operational reserve result in lower surface loading on the filter, slower pressure drop growth, and reduced long-term resistance for the fan. This leads to lower electrical energy consumption and less wear across the entire system. Conversely, an undersized filter with a small surface area quickly generates high pressure drop, significantly increasing energy costs throughout its operational life.

Filter clogging significantly increases energy consumption. As dust accumulates in the medium, pressure drop rises, forcing the fan to work harder and draw more electrical power. In practice, a clean filter operates with low resistance; however, as a dust cake forms and the filter becomes blocked, the fan must push against increasing resistance. This leads to higher electricity usage, poorer system control, and, in extreme cases, restricted airflow and reduced extraction efficiency.

Modern filtration systems deliver significant savings primarily through optimised power regulation, lower pressure drop and more efficient filter media that reduce flow resistance and slow down clogging. Combined with the extended lifespan of filter elements, this results in reduced electrical energy consumption by the fan, lower maintenance costs and longer service intervals. Crucial to this efficiency is system control based on actual demand (e.g., variable frequency drives, dampers, pressure regulation), which prevents unnecessary full-power operation, ensuring the entire system runs more efficiently and stably throughout its lifespan.

Power regulation delivers significant savings primarily by enabling the extraction system to adapt its operation to current demand. This ensures that the fan does not run unnecessarily at full capacity, leading to direct electrical energy savings. At the same time, it reduces both mechanical and aerodynamic stress on the entire system, which decreases wear on the fan, filters, and ductwork, thereby extending their service life. Consequently, in addition to lower operating costs, maintenance and servicing expenses are also reduced.

Variable frequency drives deliver savings primarily by enabling smooth adjustment of fan speeds to match actual extraction requirements, significantly reducing electrical energy consumption during partial system load. They also reduce mechanical stress on the motor and the entire system, leading to lower maintenance costs and extended equipment lifespan. However, it is important to note that a variable frequency drive alone does not guarantee savings; real benefits are only achieved when regulation is correctly designed (e.g., based on pressure, number of open branches, or extraction demand). Otherwise, the drive may simply act as an “expensive switch” with no tangible impact on energy consumption.

Demand-based control delivers the maximum possible savings across the entire extraction system by eliminating scenarios where technology runs continuously at full capacity regardless of actual operations; in practice, a significant proportion of extraction systems operate at 100% even when production is only partial or halted entirely, resulting in substantial energy losses. Precise regulation according to real demand (open branches, active machines, system pressure, or dust concentration) allows the fan output to be reduced exactly when the process permits, leading to considerable electrical energy savings, lower system pressures, reduced wear and tear, and an extended lifespan for the entire unit.

In practice, the most common way to optimise exhaust system operation is through investment in intelligent performance control. This allows the system to avoid running continuously at 100% capacity and instead respond to actual operating conditions (such as open branches, active machinery, duct pressure or filter load). This immediately reduces electrical energy consumption, stabilises pressure ratios and simultaneously decreases wear on the entire equipment. In well-designed applications, this investment pays back very quickly, often within a year, because savings on energy and maintenance are significant from day one of operation.

Operating costs of filtration equipment can be reduced by combining the right technology selection, optimisation of pressure losses and intelligent performance control. The filter concept itself has a significant impact—for example, in some applications, replacing cartridge filters with fabric (bag) filters can result in lower pressure drops and longer filter media life, leading to reduced electrical energy consumption and less frequent media changes. Further substantial savings are achieved by controlling the system according to actual demand, so that it does not run continuously at full capacity, and by rigorously minimising pressure losses through correct sizing of the filtration area, pipework and fittings; conversely, care should be taken with lamella filters, which typically have higher pressure drops and therefore higher long-term operating costs.

Compressed air consumption can be significantly reduced primarily by optimising filter regeneration so that it is driven by actual demand—typically based on the filter’s pressure drop—rather than being time-based. This prevents unnecessary pulse firing when it is not required, meaning in practice that the system regenerates only when the filter is genuinely clogged, rather than preventively or too frequently. Further savings are achieved through correct setting of intervals and pulse durations, optimisation of regeneration pressure, and a well-designed filtration area, as undersized or poorly designed filters lead to more frequent regeneration and consequently higher compressed air consumption.

The quality of regeneration has a direct impact on energy consumption, as it determines how effectively low filter pressure drop is maintained. If regeneration is effective, the filter medium remains cleaner, the dust cake is removed regularly and correctly, and the pressure drop stays at a low level. This means lower resistance for the fan and consequently lower electrical energy consumption. Conversely, poor or insufficient regeneration leads to gradual filter clogging, rising pressure drop, and significantly higher operating costs, as the fan must work against increased resistance over time. The purpose of high-quality regeneration is therefore to keep the filter in an optimal state and minimise pressure losses over time.

The simultaneous operation of multiple machines has a significant impact on the energy consumption of the extraction system, as it determines whether the system operates intelligently according to actual demand or unnecessarily runs at full capacity continuously. If the system is equipped with automatic dampers and a frequency converter with regulation, extraction adapts to the currently active machines, resulting in lower airflow, reduced pressure losses, and significantly lower electricity consumption. However, if such regulation is absent, extraction often continues to run at full power regardless of whether some machines are idle, leading to considerable energy waste, higher operating costs, and unnecessary wear on the entire technology.

Leakage in ductwork has a significant negative impact on operating costs because it causes uncontrolled air intake into the system. This increases the total airflow handled by the fan, worsens pressure conditions and leads to higher electricity consumption. Consequently, the fan must move a larger volume of air than is actually required for extraction, which increases pressure losses in the system, shifts the fan’s operating point away from its optimal range and, over time, raises both energy consumption and wear on the entire technology, including the filter and the fan.

The length of the ductwork has a direct impact on energy consumption. As the length increases, so does pressure loss due to friction between the flowing air and the duct walls, as well as from the number of fittings, bends, and branches that increase the overall system resistance; consequently, the fan must overcome higher pressure, leading to increased electrical energy consumption. In practice, however, the influence of the ductwork is typically less significant than that of the filter itself, because the pressure drop across the filter medium—and particularly the dust cake—usually constitutes the dominant component of the total system resistance.

Poorly designed ductwork has a significant impact on operating costs by directly increasing system pressure losses and, consequently, the fan’s electrical energy consumption. If designed with excessively high flow velocities, resistance in the ducts, elbows, and branches increases substantially, leading to higher energy losses and shifting the fan’s operating point outside its optimal range. In practice, it is therefore recommended for standard extraction systems to maintain flow velocities at approximately 20–22 m/s, and no more than around 24 m/s; at speeds approaching 30 m/s, pressure loss, noise levels, and operating costs rise sharply, rendering the system uneconomical in the long term. Overall, however, the impact of ductwork remains less significant than that of the filter, particularly regarding its pressure losses and fouling.

Pressure losses in the extraction system can be reduced primarily through proper design of the entire technology and optimisation of operations. The foundation lies in correct power regulation, which ensures that the system does not operate continuously under overpressure or with excessive airflow, but only according to current demand. It is also important to select filtration technologies with low pressure drop; for instance, lamellar filters are generally not recommended as they tend to have higher flow resistance, thereby increasing long-term operating costs. Correct sizing of the filter area and pipework, minimisation of unnecessary fittings and bends, and overall optimisation of fan performance so that it operates at its most efficient working point with minimal losses also play a significant role.

An oversized system has a significantly different impact on energy consumption depending on how it is controlled. If equipped with a variable frequency drive and proper regulation, its operation can be highly energy-efficient because the fan runs at lower speeds, with reduced pressure loss and only according to actual demand, thereby lowering electricity consumption while enhancing operational stability. Conversely, if control is absent, an oversized system typically operates with higher airflow than necessary, leading to unnecessarily high pressures, increased energy consumption, and inefficient performance as the fan continuously runs in a mode that does not match the real extraction requirement.

An undersized system always has a negative impact on operating costs because it operates away from its optimal point; high pressures occur in the pipework and across the filter, the fan is subjected to long-term overload, and often runs at maximum capacity without any possibility of regulation. This leads to significantly higher electricity consumption. At the same time, the system becomes harder to control, filters become clogged more quickly, pressure drop increases, and energy and maintenance costs rise further, making the entire operation inefficient and costly.

The primary advantage of returning cleaned air back into the hall is significant energy savings for heating. Since heated air is not exhausted outdoors, there is no need to constantly replace it with cold outside air that would require reheating. Furthermore, this approach reduces overall operational energy consumption, ensures more stable temperature conditions within the hall, and often decreases the required capacity of the heating system. These factors contribute to lower long-term operating costs for the entire technology.

An air recirculation volume of 10,000 m³/h delivers an annual heat saving of approximately 280 MWh during a typical heating season (around 5,500 hours) and an average temperature differential of about 15 °C. This is achieved by eliminating the need to heat an equivalent volume of cold outdoor air; in practice, this translates to savings of several hundred thousand Czech koruna per season (approximately £300–350k depending on the heat price). The actual operational benefit is often even greater due to more stable hall temperatures and reduced heating system load, although real-world utilisation may be constrained by hygiene requirements, ATEX risks, or the presence of harmful substances.

Returning air to the production hall is appropriate when it can be guaranteed that the air is hygienically safe, free from harmful substances and offensive odours—specifically volatile organic compounds (VOCs), carcinogens, toxic aerosols, and other hazardous components. In practice, this means recirculation can be safely employed in cleaner operations (such as welding shops or light mechanical engineering manufacturing) where the air is demonstrably sufficiently purified by filtration to meet hygiene standards. Conversely, in chemical plants, processes involving carcinogens, or areas generating dangerous vapours, air is typically not returned to the hall, or only within a very limited scope following a detailed risk assessment.

If air recirculation is correctly designed and filtration is sufficiently effective, it has a very positive impact on employee comfort. In practice, workers often do not even notice it, as no cold draughts are created in the hall; temperatures remain more stable and air is distributed evenly, for example through textile diffusers (textile sleeves), which ensure gentle and uniform airflow without unpleasant blowing. The result is a more stable microclimate, smaller temperature differences within the space, higher thermal comfort in winter and during transitional periods, and an overall more pleasant working environment, provided that sufficient air quality is ensured and hygiene and safety requirements are met.

Heat losses during extraction can be reduced primarily by limiting the volume of heated air expelled from the hall to the outside. The greatest savings are achieved through recirculating cleaned air back into the space, or alternatively, via partial return using heat recovery. This significantly reduces the demand for heating fresh outdoor air. It is also crucial to have a sound technical design for the system. This involves minimising leaks and implementing correct extraction zoning. The system should not extract more air than is strictly necessary. Even if the filtration unit is located inside the heated hall, heat losses do not occur directly on the unit itself. They arise indirectly because heated air is expelled from the hall to the outside. Therefore, it is not the filter’s location that matters, but rather the overall balance between extracted and returned air volumes.

Waste heat from the manufacturing process can be utilised effectively in several ways, with recovery being the most common method. This involves reusing heat from exhaust air or flue gases to warm fresh air or process media. Another option is preheating combustion air for burners, which significantly increases combustion efficiency and reduces fuel consumption. It is also very common to use waste heat for heating production halls, offices, or warehouses, as well as for water heating or other utility services. A properly designed waste heat recovery system can therefore substantially reduce overall operational energy costs and improve total efficiency.

The most common errors leading to high energy consumption in extraction and filtration systems are primarily poor design resulting in significant pressure losses caused by undersized filters, unsuitable filter media, or poorly designed ductwork with excessive air velocities. Additionally, the lack of power regulation means the system runs continuously at full capacity regardless of actual demand, while missing zonal control and dampers prevent restricting extraction to active workstations only. This is often compounded by neglected maintenance, clogged filters, and duct leaks, which further increase pressure losses and overall airflow. In practice, the greatest energy losses do not stem from the technology itself, but rather from its poor design and unregulated operation.

The return on investment for the extraction system modernisation in this case is calculated as the ratio of capital expenditure to annual savings. These savings comprise two main components: electricity savings resulting from performance regulation, and heat savings achieved through heat recovery. The methodology involves first calculating the annual electricity saving (reduced fan power consumption due to lower energy use during regulation), adding the annual heat saving (energy no longer required thanks to waste heat recovery), and summing these two figures to determine the total annual financial saving. This total is then divided by the investment costs for the modernisation, yielding the simple payback period in years. In practice, a higher proportion of regulation and heat recovery leads to a faster return on investment, as the system not only reduces fan electricity consumption but also significantly minimises building heat losses.

Modernising existing filtration equipment can deliver savings comparable to those of new systems if it enables the implementation of variable speed control and air recirculation (returning cleaned air back into the hall). In practice, this means a significant reduction in electrical energy consumption, as the fan does not run continuously at full capacity but adjusts to actual extraction requirements. It also yields heat savings by reducing the volume of heated air exhausted outdoors, thereby minimising the need for reheating. Additionally, extending filter element lifespan and lowering maintenance costs are common benefits; consequently, a well-executed retrofit can be economically competitive with new systems, provided the design is suitable for such modifications.

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Standards and regulations

Industrial extraction is subject to a range of regulations, standards and technical rules. In addition to general workplace safety requirements, it is often necessary to address fire safety, ATEX compliance, pressure equipment, emissions and the specific requirements of individual industrial sectors. Specific requirements always depend on the nature of the medium being extracted and the technology used.

A wide range of standards and technical regulations apply to filtration equipment. Specific requirements depend on the type of application, the medium being extracted, and the industrial sector. The most common areas addressed are explosion protection standards, fire safety, welding fumes, wood processing industry requirements, or emission limits.

Dust extraction is mandatory wherever dust concentrations could endanger employee health, operational safety or exceed permissible emission limits. Employers must ensure that the working environment meets occupational health protection requirements and that harmful substances are removed at source as a priority.

Workplace air quality requirements are primarily driven by the need to protect employee health. Concentrations of dust, fumes, aerosols or gases must not exceed the hygienic limits set by legislation. The fundamental principle is to remove contaminants directly at their source and ensure adequate ventilation in the workplace.

Workplace exposure limits for dust are set by health and safety regulations and depend on the type of dust and its associated health risks. There are different limits for total and respirable dust fractions, and specific values are established for certain substances. The aim is to ensure that long-term exposure does not endanger employee health.

The requirements for welding fume extraction are primarily driven by the need to protect workers’ health and ensure reliable operation. The system must effectively capture welding fumes at source, comply with hygiene limits, and simultaneously offer low operating costs and high reliability. In modern welding shops, great emphasis is also placed on energy efficiency and a long service life for filtration equipment.

Wood dust extraction must ensure the safe and reliable transport of sawdust and dust, prevent their deposition, and simultaneously meet fire and explosion protection requirements. Wood dust is classified as an explosive dust; therefore, ATEX compliance is often required for many applications. It is also crucial to maintain the correct air velocity within the ductwork and to design filters that allow for the reliable discharge of collected material.

Exhaust gas filtration imposes specific requirements on filtering equipment, particularly regarding temperature, fire safety, and the composition of the exhaust gases. The design must take into account not only normal operating temperatures but also temperature peaks, the potential presence of sparks or incomplete combustion, and the risk of filter media ignition. Protection against condensation and chemical resistance are also crucial factors.

Emission limits for industrial plants are not uniform. They depend on the type of technology, the pollutant species, the source size and the applicable legislation of the country concerned. For standard industrial filters, particulate emissions are often required in the range of single to tens of mg/Nm³, with some applications subject to significantly stricter requirements. Our technologies are designed to guarantee a residual dust emission of 1–2 mg/m³ TSP

Emission limits are established by legislation and the relevant air protection authorities. Specific values depend on the type of pollution source, the size of the operation, and applicable national and European regulations. In some cases, these limits may be further tightened through integrated permits or investor requirements.

Emissions from filtration units are measured at the filter outlet in the designated sampling location. The piping is fitted with a measurement flange, which enables authorised emissions testing to be carried out by specialised accredited companies in compliance with current legislation and relevant standards.

Emission measurement requirements encompass not only the actual measurement but also proper preparation of the measuring site. Filtration equipment must be fitted with a measuring flange and allow safe access for operators. Adequately long straight pipe sections upstream and downstream of the measuring point are also essential to ensure representative measurement results. The frequency of measurements is determined by legislation and the nature of the specific emission source.

The frequency of authorised emission measurements is not determined by the filter manufacturer but by the relevant authority. The required frequency is specified in the operating permit and depends on the nature of the pollution source and applicable legislation. It is the operator’s responsibility to ensure that measurements are carried out at prescribed intervals and that established emission limits are met.

When commissioning the filtration system, it is essential to hand over technical documentation to the operator, ensuring safe operation, maintenance and any necessary inspections. The scope of this documentation varies depending on the specific application but typically includes an operating manual, a declaration of conformity, electrical schematics and other documents related to safety and legislative requirements.

Typically supplied documents: User and maintenance manual. EU Declaration of Conformity. Electrical documentation. Pneumatic diagrams. Equipment drawing documentation. Spare parts list. Technical documentation for supplied components. ATEX certificates and documentation (if included in the supply). Inspection reports and test protocols (if within the scope of delivery). Commissioning protocol.

The Declaration of Conformity is essentially the device’s birth certificate. The manufacturer confirms in this document that the equipment meets all relevant requirements of European legislation and can be safely put into service. The document includes identification of the manufacturer, details of the equipment, and a list of directives and standards according to which the device was designed and manufactured.

CE is not a quality mark or an award. It is a declaration by the manufacturer that the device complies with all relevant requirements of European legislation. By affixing this mark, the manufacturer assumes responsibility for ensuring that the device has been designed and manufactured in accordance with the applicable directives and can be used safely.

The CE marking is required for products subject to relevant European directives or regulations. For machinery, which typically includes industrial filtration units, the CE mark is an essential requirement for placing equipment on the market and putting it into service in EU countries.

The operator of the filtration system is responsible for its safe operation, regular maintenance, and compliance with all legislative requirements. They must ensure that the equipment is used in accordance with the manufacturer’s instructions, that prescribed inspections are carried out, and that health protection, fire safety, and environmental protection standards are fully met.

The manufacturer of the filtration equipment is responsible for ensuring that the supplied unit has been correctly designed and manufactured and complies with the requirements of relevant legislation. They are obliged to supply a safe product, affix the CE marking, issue a declaration of conformity, and provide the necessary technical documentation.

The manufacturer and the operator are both responsible for the safety of the filtration system, albeit to different extents. The manufacturer is liable for the equipment’s safety within the scope of their supply and under the conditions for which it was designed. The operator is responsible for correct usage, maintenance, and safe operation of the equipment once it has been commissioned.

Air collectors for the regeneration of filtration units are typically designed and manufactured so as not to fall under the category of designated pressure equipment. This eliminates many legislative requirements associated with their operation and inspection. The collector naturally includes a safety valve and other safety components ensuring safe operation.

Compressed air used for filter regeneration must have the appropriate pressure, purity and low dew point. Inadequately treated air can cause condensation, valve fouling and problems with the regeneration of filter elements. The required air quality varies depending on the specific application and equipment location.

Electrical equipment used in industrial filters must comply with the requirements of relevant legislation and be designed for the specific operating conditions. Reliability, safety, and, in environments with explosion hazards, appropriate ATEX certification are essential. The supply includes electrical documentation, and the equipment must bear the CE marking.

Noise requirements for industrial equipment vary depending on the location of the equipment and local conditions. Different criteria apply inside manufacturing halls compared to noise emitted into the surrounding environment. When assessing outdoor noise, important factors include the distance from residential areas, property boundaries, and the requirements of relevant regulations.

The scope of inspections for filtration equipment depends on the specific application and the extent of supply. Typically, these involve electrical installations, pressure systems, fire safety components or ATEX equipment. The operator is responsible for ensuring that statutory inspections are carried out.

During operation, it is important to carry out regular inspections that help identify emerging issues before they cause equipment downtime. In addition to routine maintenance, visual checks for tightness, corrosion monitoring, and tracking of operating parameters are recommended. One of the most critical indicators is filter pressure drop, whose values should be recorded regularly.

Obtaining an occupancy permit requires more than simply installing a filter and switching on the fan. It is necessary to demonstrate that the equipment has been correctly designed, installed, and commissioned. The documentation typically includes inspection reports, a Declaration of Conformity with CE marking, technical documentation, and a commissioning protocol confirming that the design parameters have been achieved. The exact scope of required documents may vary depending on the specific building and the requirements of the local planning authority.

Failure to comply with legislative requirements can result in financial penalties, restrictions or suspension of operations, and in extreme cases, criminal liability. The amount and nature of the sanctions depend on the severity of the breach and the area concerned – for example, health and safety at work, fire protection, air quality protection, or the safety of technical equipment.

Legislative requirements in the field of air protection have been tightening over the long term. Emission limits are gradually being reduced, while demands for energy efficiency, emission monitoring and overall operational safety are increasing. Therefore, it is important to design filtration equipment with sufficient reserve capacity and in consideration of future requirements.

Returning extracted air back into the hall is only possible if its cleanliness and health safety are ensured. The air must not contain harmful substances or offensive odours, and in certain applications, particular attention must be paid to explosion risks. In ATEX applications, air recirculation is often restricted or requires specific assessment.

ATEX compliance must always be addressed whenever an explosive atmosphere is present in the process. This typically applies when extracting explosive dust or when the filtration unit itself, or parts of it, are located within an area designated as a hazardous zone with explosion risk. The scope of requirements depends on the zone classification and the nature of the extracted medium.

The most important requirement is not having a clean filter, but ensuring clean air for people in the hall. Dust should be captured as close to its source as possible and must not spread into the working area. If extraction alone is insufficient, it is supplemented by ventilation or personal protective equipment. The aim is not merely to stay just below hygiene limits, but to create an environment where people can work long-term without health risks.

The extraction of carcinogenic substances is subject to exceptionally stringent requirements. The fundamental principle is to capture harmful contaminants directly at their source and prevent them from spreading into the working environment. Great emphasis is placed on high filtration efficiency, system tightness, and the protection of employee health. In many cases, air recirculation back into the hall is not permitted.

The extraction of welding fumes must primarily ensure the protection of workers’ health. Welding fumes need to be captured as close to their source as possible so that they do not spread into the working area. High filtration efficiency, adequate air exchange and compliance with hygiene limits are essential. The requirements for welding extraction are also addressed by ISO 21904.

Explosion protection is governed by a set of European directives and technical standards. Specific requirements depend on the nature of operations, the type of explosive atmosphere, and the technology used. The objective is to prevent explosions from occurring or, alternatively, to limit their consequences to an acceptable level. ATEX 2014/34/EU – Requirements for equipment and protective systems intended for use in potentially explosive atmospheres. ATEX 1999/92/EC (ATEX 137) – Minimum requirements for improving the safety and health protection of workers potentially at risk from explosive atmospheres, including classification of areas. ČSN EN ISO 80079-36 and 80079-37 – Non-electrical equipment for use in potentially explosive atmospheres. ČSN EN 60079 – Electrical apparatus for explosive gas atmospheres. ČSN EN 14491 – Explosion relief venting for equipment with dust explosion hazards. ČSN EN 14373 – Explosion suppression (HRD systems). ČSN EN 15089 – Explosion isolation in pipework systems. ČSN EN 14986 – Requirements for fans for use in potentially explosive atmospheres. ČSN EN 1127-1 – Prevention and protection against explosions, basic principles. ČSN EN 12779 – Extraction plant for the wood-processing industry.

The safety of machinery is governed by European legislation and a set of technical standards. The aim is to ensure that equipment remains safe throughout its entire lifecycle—from installation and commissioning through to maintenance and disposal. Manufacturers must conduct risk assessments and design machinery so that risks are eliminated or reduced to an acceptable level.

EU Machinery Regulation 2023/1230 (formerly Directive 2006/42/EC).

ČSN EN ISO 12100 – Safety of machinery – Risk assessment.

ČSN EN 60204-1 – Electrical equipment of machines.

ČSN EN ISO 13849-1 – Safety-related parts of control systems.

ČSN EN ISO 14120 – Guards and protective devices.

ČSN EN ISO 13850 – Emergency stop function.

Industrial fans are governed by a range of standards and regulations concerning safety, construction, energy efficiency, and, where necessary, explosion protection. Specific requirements depend on the type of fan and its intended application. CSN EN ISO 5801 – Determination of fan performance characteristics. CSN EN ISO 13349 – Vocabulary and definitions used for fans. CSN EN 14986 – Design requirements for fans for use in explosive atmospheres. CSN EN ISO 80079-36 and 80079-37 – Non-electrical apparatus for use in explosive atmospheres. CSN EN 60204-1 – Electrical equipment of machines. CSN EN ISO 12100 – Risk assessment for machinery. EU Machinery Regulation 2023/1230. EMC and LVD directives for electrical components. ATEX 2014/34/EU, if the fan is intended for use in explosive atmospheres.

A range of standards and technical regulations apply to suction duct systems. Specific requirements depend on the nature of the medium being extracted, operating conditions, and any risk of fire or explosion. Key factors include not only the strength of the ducting but also its tightness, earthing, and correct sizing.

BS EN 12779 – Extraction equipment for the wood-processing industry.

BS EN 1127-1 – Prevention and protection against explosions.

BS EN 14491 – Explosion relief.

BS EN 15089 – Isolation of explosions in duct systems.

ATEX 2014/34/EU and 1999/92/EC – Equipment and workplaces with explosion hazards.

BS EN ISO 80079-36 and 80079-37 – Non-electrical equipment in explosive atmospheres.

BS EN ISO 12100 – Risk assessment for machinery.

Fire safety regulations and local legislative requirements.

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ATEX and explosion protection

ATEX is a set of European regulations and technical requirements for equipment operating in environments with explosion hazards. The aim of ATEX is to prevent the creation of an ignition source, such as sparks or hot surfaces, and to minimise the consequences of any potential explosion. ATEX requirements apply to both electrical equipment and mechanical components, such as filters, fans, rotary feeders, or pipework systems.

ATEX compliance is required wherever an explosive atmosphere may be created by dust or gas. Typical examples include the wood processing industry, biomass production, mills, food manufacturing, foundries, aluminium plants, and facilities handling organic dusts. If combustible dust can be present in the air at sufficient concentration and there is a potential ignition source, technology must be designed in accordance with ATEX requirements.

The risk of explosion must be addressed during the design phase of the equipment. The foundation lies in knowing exactly which dust will be extracted by the filter. Based on a PTCH protocol for the specific dust or through established dust databases, its explosive properties are determined, thereby defining the requirements for the ATEX-rated design of the filter, pipework, and protective components. Without knowledge of the specific dust involved, it is impossible to safely design an appropriate extraction system.

An explosive atmosphere can be created by surprisingly common materials. These include wood dust, biomass, flour, sugar, starch, plastic powders, aluminium, magnesium, coal, paper, textile fibres and certain chemical substances. The solid material itself is not hazardous; rather, it is the fine dust dispersed in the air that, at a specific concentration, can form an explosive mixture.

Yes, wood dust is explosive. Fine wood particles dispersed in the air can create an explosive atmosphere when they reach a certain concentration. If an ignition source appears simultaneously—for example, a spark, a hot particle, or an electrostatic discharge—an explosion may occur. Therefore, extraction systems for the woodworking industry are typically designed in compliance with ATEX requirements and utilise antistatic filter media, pressure relief panels, and other protective devices.

Yes, aluminium dust is highly explosive. While wood dust is considered standard in ATEX applications, aluminium demands significantly greater attention. We must always know the specific properties of the dust from PTCH or dust databases to design filters, antistatic media, and protective components accordingly. Nothing can be guessed when it comes to aluminium. Beyond standard filtration, we often incorporate sorbent dosing. Sorbents help bind moisture, reduce dust stickiness, and improve the regeneration of filter media. This extends filter life and increases the reliability of the entire system. It is precisely this modification of dust properties that sets us apart from conventional solutions.

Yes, plastic dust can be explosive, but this depends heavily on particle size. Fine plastic dust dispersed in the air can create an explosive atmosphere and must be assessed under ATEX regulations. Conversely, coarser particles, such as plastic shavings produced during machining, typically do not form an explosive atmosphere, and the risk of explosion is significantly lower. Therefore, each application must be evaluated individually based on the nature of the material and particle size.

Yes, coal dust is explosive and, under ATEX regulations, is classified as a well-known combustible dust. Fine particles of coal dispersed in the air can create an explosive atmosphere; therefore, extraction systems must be designed with appropriate explosion protection measures. However, such applications are becoming increasingly rare today, given the gradual decline in the use of coal within industry and energy production.

Yes, flour is explosive. Fine particles of flour dispersed in the air can create an explosive atmosphere, and if an ignition source is present, an explosion may occur. This is precisely why mills, bakeries, and other food processing facilities are considered classic ATEX applications. The risk primarily concerns fine flour dust, rather than whole bags or bulk storage of flour itself.

The most common cause of a dust explosion is the ignition source arising in an environment with an explosive atmosphere. This can be an electrical spark, electrostatic discharge, hot particle, overheated bearing or, for example, incomplete combustion from a technological process. In practice, unfortunately, we also encounter human error, such as discarding a cigarette butt into the extraction system. It is precisely the combination of combustible dust, oxygen and an ignition source that can lead to an explosion.

An explosive atmosphere is a mixture of flammable dust or gas with air in such concentration that, upon ignition, rapid flame propagation occurs throughout the entire volume of the mixture. In industrial extraction systems, we most commonly encounter explosive atmospheres formed by fine dust dispersed in the air. If an ignition source, such as a spark or hot particle, is present simultaneously, an explosion may occur.

The minimum explosive concentration (MEC) is the lowest concentration of combustible dust dispersed in air that can result in an explosion upon ignition. If the dust concentration is lower, an explosive atmosphere will not form. The MEC value is determined in a laboratory and is one of the key parameters used when designing equipment to comply with ATEX requirements.

The Minimum Ignition Energy (MIE) is the lowest spark or ignition source energy capable of igniting a dust-air explosive mixture. The lower the MIE value, the more sensitive the dust is to ignition. This parameter is determined in laboratory conditions and is one of the key data points for designing equipment in compliance with ATEX requirements.

Explosion hazard zones are areas where an explosive atmosphere formed by dust or gas may occur under certain conditions. The classification into specific zones is based on the frequency and duration of such atmospheres. The aim is to determine what equipment and protective measures must be used in a given area.

The difference between zones 20, 21 and 22 lies in the likelihood of an explosive atmosphere occurring. The more frequently a combustible dust mixture is present, the stricter the requirements are for the equipment used. Zone 20 – An explosive atmosphere is present continuously, frequently or for long periods. This typically applies to internal spaces such as filter housings, silos and storage bins. Equipment in category 1D is used for this zone. Zone 21 – An explosive atmosphere may occur occasionally during normal operation. A typical example would be the area around a filter discharge point, filling stations or transfer points. Equipment in category 2D is used here. Zone 22 – An explosive atmosphere occurs only exceptionally and for short periods, such as during a fault or leak. This typically applies to the vicinity of filtration units or pipework routes. Equipment in category 3D is used for this zone.

Zones 0, 1 and 2 are used in environments with the risk of gas, vapour, or mist explosions. The difference between them lies in the likelihood of an explosive atmosphere occurring. The more frequently an explosive mixture is present, the higher the requirements placed on the equipment used.

Zone 0 – An explosive atmosphere is present continuously, for long periods or frequently. Typically found inside tanks or pipelines containing flammable gases. Category 1G equipment is used.

Zone 1 – An explosive atmosphere may occur occasionally during normal operation. A typical example is the area around pumps, valves, or filling points. Category 2G equipment is used.

Zone 2 – An explosive atmosphere occurs only rarely and for short periods, such as in the event of a fault or leak. Category 3G equipment is used.

Defining zones is not the responsibility of the filter manufacturer but rather ATEX specialists. Zones are typically established by a commission comprising representatives from the operator, the designer, fire safety experts, and ATEX specialists. Based on dust properties, technology, and the likelihood of an explosive atmosphere occurring, an Explosion Protection Document is prepared to define individual zones and equipment requirements. The filter manufacturer then designs the technology to meet these requirements.

Not all extraction systems require an ATEX design. ATEX requirements apply only to technologies that extract explosive dusts or gases, or are installed in areas classified as explosion hazard zones. If the material is non-explosive and the equipment is not located within an ATEX zone, a special ATEX design is not required.

ATEX certification is not required when extracting non-explosive dust and the filtration unit or its surroundings are not classified as an explosive atmosphere zone. If an explosive atmosphere cannot occur, no special ATEX requirements apply to the equipment.

In an ATEX version, the entire filtration unit can be practically included. This comprises the filter housing itself, filter media, fans, electrical components, rotary feeders, pressure relief membranes, flameless venting systems FLEX and backdraft dampers B-FLAP. Each component must be designed to meet the requirements of the specific zone and the characteristics of the extracted dust.

Explosion relief is a safety measure that deliberately releases pressure into the surrounding area during an explosion, preventing damage to the filtration equipment. Explosion relief membranes are most commonly used; these open when a specific pressure threshold is reached, allowing safe venting of the pressure wave and flame. This significantly reduces the consequences of any potential explosion.

Explosion relief membranes are designed to relieve pressure generated by an explosion within the filtration unit. Upon reaching a predetermined pressure, typically around 10 kPa, the membrane ruptures in a controlled manner, allowing the safe venting of the pressure wave and flame into the surrounding environment. This prevents damage to the filter and significantly mitigates the consequences of the explosion.

Flameless explosion venting devices are used in situations where filtration equipment is located inside a building and it is not possible to safely route flames to the outdoors. The principle is similar to that of an explosion relief membrane: during an explosion, the membrane opens, but hot gases and flames subsequently pass through a special stainless steel quencher, which cools them sufficiently so that no flame emerges into the surrounding area. This enables safe explosion venting even within buildings.

Explosion suppression is an active explosion protection system designed to halt a developing explosion at its earliest stage. A typical solution involves HRD barriers, which inject a fire-extinguishing medium into the protected space within milliseconds of detecting a rapid pressure rise, thereby preventing further progression of the explosion. This prevents dangerous pressure increases and stops the spread of the explosion to other parts of the plant.

The explosion isolation section is a protective measure designed to prevent the transmission of an explosion from one piece of equipment to another. Its role is to halt the propagation of flames and pressure waves through piping into downstream sections of the process technology. One of the most common components for explosion isolation is a rotary feeder, which, due to its design, can effectively prevent the transmission of explosions between the filter and the connected processing equipment.

The propagation of an explosion into the pipework is prevented by means of explosion isolation devices. The most commonly used solutions are backdraft dampers (B-FLAP), fast-acting HRD barriers, or correctly designed rotary airlocks. These components prevent flame and pressure wave propagation to other parts of the plant, thereby limiting the consequences of any potential explosion to a single piece of equipment.

The rotary feeder is a device located beneath the filter discharge, designed to ensure the smooth removal of captured dust or material while maintaining the system’s air-tight integrity. In ATEX-compliant applications, a certified rotary feeder can simultaneously serve as an explosion isolation unit, preventing flame and pressure wave propagation into downstream sections of the process technology.

Spark detection is an active safety system designed to detect and extinguish sparks or hot particles in the extraction system at an early stage. Detectors are most commonly installed in ductwork, where they activate fire suppression nozzles upon spark detection, preventing sparks from being carried into the filter. Alternatively, detectors can be installed directly within the filtration unit, where they may trigger the fire suppression system or shut down the process technology upon detecting a spark.

The fire suppression system is suitable for applications where there is a risk of fire or where a potential fire could cause extensive damage to technology or endanger the safety of personnel. It is most commonly used in conjunction with spark detection, whereby the fire suppression system activates automatically upon detection of sparks or elevated temperatures. Fire suppression systems are primarily installed in filters, mills, conveyor systems, or pipework networks that present a higher risk of ignition.

Grounding the equipment is crucial for the safe operation of extraction systems. Its primary role is to dissipate the electrostatic charge generated by the flow of dust and air through ducts, filters, or other components. This reduces the risk of an electrostatic discharge, which could serve as an ignition source in environments with explosive atmospheres.

Electrostatic discharges can constitute an ignition source for explosive atmospheres. If flammable dust or gas is present in the extraction system, even a very small spark caused by accumulated electrostatic charge can initiate an explosion. Therefore, antistatic filter media, conductive components and thorough earthing of the entire equipment are used in ATEX applications.

In explosive atmospheres, filter media must be manufactured in an antistatic version. Conductive fibres or fine metal wires are woven into the filter fabric to ensure the safe dissipation of electrostatic charge generated during air and dust flow. This prevents the occurrence of electrostatic discharges that could initiate an explosion.

ATEX fans are designed based on whether the explosive atmosphere may be present inside the fan, in its vicinity, or in both areas simultaneously. Therefore, requirements for internal and external zones are distinguished. The fan construction, impeller material, clearances between rotating parts, and motor design are selected to prevent any source of ignition from arising.

Yes, explosion-proof filters can also be installed indoors. However, in such cases, standard explosion venting to the surrounding area cannot be used, as this would allow flames and pressure waves to escape into the hall. Therefore, flameless explosion vents (FLEX) or active explosion suppression systems using HRD barriers are employed. Both solutions enable safe operation of the filter unit even within enclosed spaces.

Deflagration venting is required when it is not possible to safely direct the pressure and flame from an explosion vent into open outdoor areas. This typically applies to filters located inside buildings or outdoors in locations where there is insufficient safe clearance, such as between structures, under shelters, or near roads and process equipment. In such cases, FLEX systems are used to allow pressure relief while capturing and quenching the flame.

One of the most common errors in the design and operation of ATEX equipment is not the initial design itself, but subsequent changes to the process without informing the supplier. A filter designed for steel grinding may not be suitable for aluminium or other explosive materials. Changes in dust properties can significantly impact explosion protection requirements, meaning the original equipment may no longer meet the required safety standards.

For ATEX applications, several documents are required. The foundation is the Documentation on Explosion Protection (DoEP), which defines explosion hazard zones and requirements for individual equipment. Additionally, dust property reports (DPRs) or data from dust databases, declarations of conformity, and ATEX certificates for individual components are essential. The documentation typically also includes operating and maintenance instructions for the equipment.

The manufacturer of the filter is not responsible for defining explosion hazard zones; this falls to the plant operator or investor. In practice, these zones are typically determined by an expert panel comprising representatives from the investor, the design engineer, fire protection specialists, and ATEX experts. The outcome is a Document on Explosion Protection, which defines the individual zones and requirements for the equipment used.

The manufacturer of the equipment is responsible for its explosion protection. They must design and supply the equipment so that it meets the requirements of relevant standards, aligns with the client’s specifications, corresponds to the properties of the extracted dust, and adheres to the designated hazardous zones. The manufacturer is also responsible for ensuring the correct functioning of the protective components used and provides the necessary documentation and declaration of conformity.

Explosion risk assessment is the process of evaluating whether and where an explosive atmosphere may arise, as well as the potential consequences of any explosion. It takes into account the properties of dust or gas, technology, operating conditions, possible ignition sources, and equipment protection methods. The outcome is a proposal for appropriate protective measures and the designation of zones with explosion hazards.

ATEX is found across many industrial sectors and extends far beyond the chemical industry. It is most commonly encountered wherever fine combustible dust is generated or flammable gases are handled. Typical examples include wood processing, biomass production, food manufacturing, recycling, plastic processing, non-ferrous metal production and machining, and the energy sector.

One of the most common myths is the belief that ATEX applies only to the chemical industry. In reality, explosive dusts are encountered in wood processing, food production, recycling, and aluminium machining. Another misconception is that ATEX means an explosion cannot occur. In fact, the aim of ATEX is to reduce the likelihood of an explosion occurring and to minimise its consequences.

The consequences of underestimating explosion protection can be fatal. An explosion may cause serious injuries or loss of life, extensive damage to technology and buildings, and long-term disruption of production. Therefore, properly designed explosion protection is not merely a matter of regulatory compliance but primarily the safeguarding of people and assets.

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Filter units

The filtration unit is the technology where solid particles are separated from the air. Simply put, it is the place where contaminated air is converted into clean air. Its role is to capture dust, smoke or aerosols and ensure safe and environmentally friendly operation of the manufacturing process.

A properly designed system works in such a way that you hardly notice it. It extracts, filters, cleans itself automatically and does not require constant attention from the operator. If the customer has to look after the filter every week, something is wrong.

There are many types of filtration units, but in practice we most commonly encounter cartridge, sintered pleated and fabric filters. Cartridge filters tend to have a shorter lifespan and more expensive replacement filter elements. Sintered pleats last very long, but the customer often pays for this with higher electricity consumption due to increased pressure drop. Based on our experience, fabric filters represent the best compromise and are therefore most frequently recommended. For high temperatures we use ceramic or metal filters, and in some special applications electrostatic or wet scrubbers, but these are used very limitedly.

The best advice? Don’t try to become a filtration expert over a single weekend. There is a high chance you will select an unsuitable technology or underestimate important parameters. That is exactly what specialist companies are here for—they have been doing this their entire lives. Even we occasionally encounter the unexpected.

Price is important, but it should certainly not be the only criterion. The performance of the equipment, electrical energy consumption, lifespan of the filter media and price of spare parts are equally significant. A cheap filter can become significantly more expensive over several years of operation than a pricier unit with low running costs.

Frankly, we would not recommend that customers determine the filtration area themselves; that is the supplier’s role. If a customer specifies how many square metres of filtration area they require, they assume part of the responsibility for the equipment’s performance, which is precisely what should be avoided. It is far more sensible to request a guarantee on the service life of the filter media from the supplier—for example, a minimum of 20,000 operating hours. How this is achieved should be their know-how.

The difference lies in whether the fan is positioned before or after the filter. If it is located upstream of the filter, it must handle dusty air, which necessitates a more robust but less efficient design and results in higher electricity consumption. With negative pressure filtration, the fan operates with clean air, allowing for greater efficiency and typically lower operating costs. Therefore, we prefer negative pressure filtration units in most cases.

Honestly, the difference is mainly in shape. Internally, everything is very similar – same filter media, same regeneration and similar components. Square filters are used most frequently, while circular designs are chosen primarily where high vacuums are involved, such as in central vacuum systems or other special applications.

We honestly believe that there has been a lot of marketing hype around the concept of modularity. If you need a larger filter, you still have to purchase additional unit components, filter media, and often modify the fan or ductwork. Connecting an extra module does not deliver the significant savings sometimes claimed. We manufacture modular filters, but we have yet to expand our range with them.

The advantage of modular filters lies primarily in their expandability. This makes sense, for example, when it is necessary to maintain the existing waste route or when the customer anticipates a gradual increase in production. However, I would not expect modularity to deliver dramatic investment savings. Its main benefit lies in flexibility rather than cost.

We recommend allowing for a filter area reserve of around 20%. Over the years, we have yet to encounter a customer who did not wish to add something extra after a few years. A slightly larger filter is usually no problem. Conversely, an undersized filter tends to cause issues throughout its entire lifespan.

It’s simple: as air heats up, it expands. The filter must expand accordingly. If the volume of air doubles at higher temperatures, the size of the filtration unit must also roughly double. Physics cannot be cheated.

The biggest enemy of filter units is not high humidity, but condensation. Once water begins to condense, dust starts to stick and problems soon follow. That is why we often address insulation, heating or sorbent dosing to reduce moisture levels. Preventing condensation is always more cost-effective than dealing with a clogged filter later on.

A higher dust concentration requires a larger filter. It is necessary to operate at a lower filtration rate, as the dust cake builds up more quickly and regeneration occurs more frequently. If the filter is too small, compressed air consumption increases, the lifespan of the filter media decreases, and operating costs rise. Therefore, in dusty applications, it is not cost-effective to compromise on filter area.

The most common cause of clogging is not the dust itself, but an unsuitable choice of filtration technology. In practice, we frequently encounter cartridge filters where the gaps between the pleats are very narrow. Dust gradually compacts within these spaces, and even strong pulses of compressed air cannot reliably remove it. Moreover, regeneration deforms the cartridge, and in some cases, can cause the dust to become even more trapped in the crevices. The result is increasing pressure drop and progressive filter clogging.

The most common cause of high pressure drop is an excessively high filtration rate. Simply put, the filter is too small and there is too much dust. Another reason may be the filter element itself. Some technologies inherently exhibit a high pressure drop. A typical example is sintered lamellar filters, where customers gain long service life but pay for it through higher electricity consumption.

A clogged filtration unit is usually noticed first by the machine operator. They simply observe that suction performance has declined, allowing dust or fumes to escape into the workspace. Typical signs include reduced suction power, increased pressure drop, and the fan operating at maximum capacity. In practice, therefore, an experienced operator standing by the machine serves as the most effective sensor.

It may sound odd, but a well-designed filter is one the customer doesn’t even know about. Aside from regular waste disposal and occasional checks, it requires no further attention. If the filter becomes a daily concern for operators, something likely went wrong in its design.

Surprisingly, most faults in filter units are not related to the filter itself. From our experience, a significant proportion of issues with outdoor installations stem from the freezing of regeneration valves at low temperatures. Subsequent troubleshooting often reveals that the compressed air adsorption dryer is either bypassed or not functioning correctly. Once the issue with air drying is resolved, the filter unit typically returns to full operational capacity.

A correctly designed filter rarely requires cleaning. Initially, a dust cake forms, which is actually beneficial for the filter. Regeneration only initiates once the pressure drop reaches a specific threshold. A short pulse of compressed air blows through the filter media in reverse flow, causing part of the dust to fall into the hopper and reducing the pressure drop again. The regeneration then switches off, and the entire cycle repeats.

Most filters operate at 6 bar pressure, with smaller units often requiring just 5 bar. However, the quality of compressed air is far more critical than pressure alone. Moist air reliably leads to frozen valves and regeneration issues. Therefore, for outdoor installations we require a dew point of at least -40 °C, whereas +5 °C is usually sufficient indoors.

The filter is usually not the weakest link in the system. That role typically falls to compressed air. If it is humid, regeneration valves freeze during winter. If it contains mechanical impurities, solenoid valves and diaphragms begin to stick. Experience shows that properly dried and filtered compressed air is one of the fundamental prerequisites for long-term trouble-free operation of the filtration unit.

The hopper beneath the filter does not merely serve to collect dust. If a rotary feeder is not employed, it also provides pressure isolation between the filter and the surrounding environment. It is crucial to size the hopper correctly. When extracting sawdust, you cannot place a 50-litre container under the filter; it will fill up quickly, leaving operators with nothing to do but dispose of the waste.

There are numerous options available. These range from simple 50-litre buckets to 200-litre and 1,000-litre containers, up to rotary feeders with Big Bags. For larger volumes of dust, pneumatic conveying into a silo, closed container, or briquetting press is often employed. A particularly elegant solution involves a closed-loop pneumatic conveying system into a container; this ensures that operators have virtually no contact with the dust and eliminates the need to construct a silo.

The screw conveyor makes sense when you need to move dust elsewhere than under the filter. Typically into a briquetting press, silo or separate room. There is no reason to make operators run around with buckets when the machine can do it for them.

If excessive waste accumulates beneath the filter, buckets and bins become impractical. In such cases, we utilise a rotary feeder that enables continuous dust extraction while the filter is in operation. This means operators no longer need to manage constant emptying, allowing the entire system to function automatically.

The production space is usually too expensive to be occupied by the filter. Therefore, outdoor installation often makes economic sense. With explosive dusts, it is also almost always a more advantageous solution because the explosion relief can be directed into open space and the customer does not need to invest in expensive flame arrestors.

If there is space for the filter inside the hall, its location is often advantageous. Shorter ductwork means lower pressure loss, reduced fan power and lower electricity consumption. While a few dozen metres of ducting is not an issue, having the filter close to the technology is usually the more energy-efficient solution.

The filter is essentially as large as the required extraction capacity dictates. This determines the necessary filtration area and, consequently, the dimensions of the entire unit. Over the years, however, we have not yet encountered a space where we could not design a suitable solution. The key consideration is simply ensuring access for servicing and replacing the filter media.

It is important to distinguish between the lifespan of the filter housing and that of the filter media. The filter unit itself should operate without issue for 20 to 30 years. The situation with filter elements is quite different. With cartridges, a service life of 2,000 to 4,000 hours is commonly encountered in practice, whereas for fabric bags, 20,000 operating hours is considered the absolute minimum.

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Welding fume extraction

Welding fume is not extracted for the sake of filters, but for people. It contains fine particles and substances, some of which are classified as carcinogenic. Long-term exposure to these harmful agents can have serious health consequences. Therefore, we prefer capturing the fume directly at its source rather than allowing employees to breathe it in or letting it disperse throughout the entire hall.

Welding fumes are not just ordinary smoke. They contain very fine metal particles, residues of burnt oils and lubricants, iron oxides, manganese, nickel, and when welding stainless steel, hexavalent chromium, which is classified as a carcinogenic substance. Additionally, harmful gases such as nitrogen oxides or ozone may be generated. Therefore, we consider the extraction of welding fumes primarily as a means to protect people’s health, not merely as compliance with legislative requirements.

If smoke is generated during welding, it should be extracted. It does not matter whether you are performing MIG, MAG, TIG, plasma or robotic welding. All welding processes produce harmful substances; the difference lies only in their quantity and the method of extraction. The primary objective is always to protect people’s health, rather than waiting until smoke becomes visible in the hall.

Absolutely yes. A robot cannot go for a snack, does not take cigarette breaks and operates with much higher efficiency than a human operator. This is precisely why it generates significantly more welding fumes than manual workstations. Therefore, we consider the extraction of robotic cells to be an absolute necessity.

Yes. In manual welding, it is less about the technology and more about the person. Welding fumes should not end up in the welder’s lungs. Therefore, it makes sense to capture them as close to the arc as possible and prevent them from dispersing throughout the entire hall.

Local extraction captures smoke at its source and requires significantly less power. Spatial extraction deals with smoke only after it has dispersed throughout the hall and accumulated under the ceiling. This means a substantially higher volume of air is required, leading to increased operating costs. Therefore, if technology permits, we always recommend local extraction. Central spatial extraction is primarily used for large weldments where the welding operator cannot easily reach the heat source with an extraction arm.

Local extraction is sufficient for smaller specialist workstations where the size of weldments does not vary significantly and it is possible to position the extraction unit close to the source of fume. It also works very well in robotic cells, where the entire working space of the robot is typically extracted. Capturing smoke directly at its source is almost always more effective and cost-efficient than extracting from an entire welding shop.

We recommend centralised welding extraction in almost all cases where more than one welding station is operational. In practice, this applies to virtually all industrial welding environments. A single central filtration unit is typically more cost-effective, easier to maintain and allows for simpler future production expansion. The question is rarely whether to use centralised extraction, but rather how best to capture welding fume at each individual workstation.

We design our filtration units as technical equipment tailored to specific operational requirements, rather than generic off-the-shelf catalog items. Key factors include flow rate, dust load, temperature, emissions, ATEX compliance, space constraints, maintenance needs, and energy consumption. Therefore, at G&G Filtration, we work with a 3D model of the specific unit during the quotation phase so that both the customer and the designer know exactly what will be delivered.

The most effective extraction is achieved with a robotic cell that is fully enclosed, including the ceiling. In this case, it suffices to extract air from within the cell volume, making the design relatively straightforward. For small robots, we estimate approximately 2,000 m³/h; for larger units, around 3,500 m³/h; and for large robots or intensive welding operations, 5,000 m³/h or more. The better sealed the cell is, the lower the required extraction capacity. Although a significantly lower airflow would technically suffice, the priority is ensuring that when the cell doors are opened, fumes do not spill out towards the operator.

Welding table extraction can be achieved using either an extraction arm or an extraction hood. An extraction arm is suitable where the welding position changes frequently, allowing the operator to adjust the nozzle as close as possible to the smoke source. For repetitive tasks or larger tables, an extraction hood often makes more sense; it draws welding fumes away from the worker and prevents them from spreading into the breathing zone. The objective is always to capture the fumes as early as possible, rather than waiting for them to disperse throughout the entire hall.

For multiple welding stations, it is important to design the ductwork so that smoke and fine dust do not settle. The flow velocity is maintained at approximately 18 m/s and should not drop unnecessarily, as deposits in the welding extraction system can cause operational and fire hazards over time. Therefore, the ducting is designed with a stepped configuration to keep the flow velocity as constant as possible. For a larger number of stations, automatic dampers and fan speed control based on the actual number of open extraction points are recommended.

The required air flow rate in welding workshops is determined by the method of fume extraction. For extraction arms, a typical calculation is approximately 1,200 m³/h per workstation. With a rear-mounted extractor hood on a welding table, this is roughly 1,500 m³/h per metre of length. Robotic cells typically range from 2,000 m³/h for smaller robots, through 3,500 m³/h for larger workstations, up to 5,000 m³/h and above for large robots or intensive welding operations. For ceiling-level extraction across an entire welding workshop, a baseline figure of approximately 5,000 m³/h per workstation can be used as a guide.

With welding fume, it is important not only to capture it at the source but also to transport it safely through ductwork to the filter. For duct runs, we recommend a flow velocity of approximately 18 m/s. At lower velocities, fine dust deposits can form, which present not only an operational issue but may also cause the ducting to ignite. Therefore, we design the duct system so that the flow velocity does not drop unnecessarily.

The extraction nozzle should be positioned as close to the weld as possible, ideally within 500 mm. At greater distances, capture efficiency drops significantly. This is not only a technical issue but also a practical one: if the operator’s extraction arm proves cumbersome, they are unlikely to use it correctly.

The position of the extraction nozzle has a significant impact on suction efficiency. If the nozzle is too far away, welding fumes disperse into the surrounding area and capture effectiveness drops considerably. Conversely, if it is too close, it can disrupt the protective welding atmosphere and negatively affect weld quality. Based on our experience, a reasonable compromise is a distance of approximately 500 mm from the welding point.

The biggest mistakes are made right at the start. Incorrectly specified extraction capacities can ruin an entire system. Another issue is using pipe diameters that are too large; while they result in low pressure loss, the flow velocity becomes so low that deposits form inside. You certainly do not want these with welding fumes due to the potential fire hazard. A third common problem involves cartridge filters with media of short lifespan and high replacement costs.

Inadequate extraction in welding areas is usually identified very quickly. Visible smoke can be seen in the hall, welding fume lingers near the ceiling and workers complain of respiratory irritation or coughing. These are clear signs that harmful substances are not being captured by the filter but are ending up in employees’ lungs.

The main advantage of extraction arms is their flexibility. The operator can move the extraction nozzle precisely to where welding is taking place, achieving highly effective fume capture. However, a drawback is that the arm must be constantly repositioned by the worker. In practice, we often find that this manipulation slows welders down, and after a certain period they either stop using the arms correctly or cease using them altogether.

If smaller parts up to approximately 1.5 metres are being welded together, an extraction table is an excellent solution. We prefer rear hoods over extraction arms, as they cover the entire surface of the table. This allows the welder to focus on their work without having to constantly reposition the arm.

If the welder moves around the large welded joint from all sides, an extraction arm is of limited use and a rear hood becomes impractical. In such cases, top-down extraction is the simplest solution. The operator can move freely without the extraction system hindering their work.

Large-scale welding operations are typically managed using spatial extraction systems. With large structures, it is practically impossible to keep the extraction nozzle in an optimal position at all times. Based on our experience, decentralised systems have proven highly effective; these feature lightweight aluminium filtration units with full regeneration capacity installed near the hall ceiling. The captured dust is then extracted centrally to a single point, meaning operators do not need to manage several separate containers. This approach is more energy-efficient due to the minimal ductwork required.

Bridge structures and other large components are best managed using a decentralised spatial extraction system. With such substantial welded assemblies, it is not practical to use extraction arms or other local capture methods. Compact filtration units with full regeneration capabilities are installed beneath the hall ceiling, capturing welding fume as it naturally rises. The captured dust is then centrally conveyed to a single point via a high-pressure system.

Robotic lines can be addressed in two fundamental ways. The first is central extraction, where individual robotic cells are connected via ducting to a single common filtration unit. The second option is a decentralised system, featuring a compact filtration unit with full regeneration capabilities positioned above each cell. The captured dust is then conveyed pneumatically under high pressure to a single central collection point.

Aluminium dust extraction is essential primarily to prevent the accumulation of explosive dust in the workplace. The filter itself must comply with ATEX requirements and be equipped with a B-Flap, pressure relief panels, and sufficient pressure resistance. Equally important is preventing deposits from forming in the pipework and maintaining adequate airflow velocity.

Requirements for extracting stainless steel dust are technically similar to those for other non-explosive metal dusts. The main objective is to capture fine particles and welding fumes as close to the source as possible, preventing inhalation by workers. Particular attention must be paid to health protection, as harmful substances, including hexavalent chromium, can be generated during stainless steel welding.

MIG, MAG and TIG welding differ primarily in the intensity of fume generation and the composition of harmful substances. MIG and MAG welding produce large quantities of fine particles and require effective extraction systems. TIG welding generates significantly less fume, but extraction should not be underestimated here either. Furthermore, the composition of harmful substances varies depending on the base material, filler wire and shielding gases used.

Yes, filtered air can be returned to the hall. Modern filtration units are capable of capturing dust particles with such efficiency that recirculation is possible in most applications. However, this requires that the extracted air does not contain VOCs, odours, exhaust fumes or other gaseous pollutants that cannot be removed by standard filtration.

The most effective way to reduce heat loss during welding fume extraction is to return the filtered air back into the hall. We can capture dust particles at such a level that, in most applications, there is no need to exhaust expensive heated air outside. If odour is an issue, it can be mitigated through adsorption using zeolite or other sorbents. Since most of the cleaned air is returned to the hall, heat recovery typically does not make economic sense.

The efficiency of welding fume extraction is not improved by using a larger fan, but rather by capturing the fumes correctly. The foundation lies in selecting an appropriate extraction device and designing the extraction capacity accurately. The closer you can capture the fumes at their source, the lower the air volume required and the higher the overall system efficiency.

The cause is often oily sheets. Oils and preservatives evaporate during welding and subsequently form a sticky coating on the filter media. Dust then fails to regenerate properly, leading to filter blockage. From our experience, sorption using zeolite works very well; it binds the oily components and prevents the filter from becoming clogged.

The biggest enemy of filter media is not dust, but oil. Even worse are the separation fluids used in robotic workstations. These can clog even a well-designed filter. Therefore, we recommend zeolite sorption for these applications. It is more cost-effective to dose sorbent continuously than to replace clogged filter media regularly.

A typical sign of filter bags becoming clogged with fatty particles is persistently high pressure drop, which does not significantly decrease after regeneration. Another indicator is the fact that almost no dust appears in the discharge hopper or bucket. This is because the dust does not fall off but remains as a sticky coating on the surface of the filter bags. In such cases, regeneration loses its effectiveness and it is necessary to remove the cause, which are most often oil aerosols or separation fluids.

If I had to choose one factor that most significantly extends the lifespan of filtration media during welding, it would undoubtedly be sorbent action. Zeolite dries, degreases and simultaneously reduces odours. The filtration media regenerate more effectively and their service life is considerably extended. It’s a win-win solution.

The sorbent station is essentially a hopper for finely ground zeolite. The operator loads a bag of sorbent into it, and the auger breaker and dosing unit ensure smooth metering, while a small fan periodically conveys the material into the suction duct. The zeolite mixes with welding fumes, drying and degreasing the dust whilst simultaneously reducing odours. This results in lower pressure drop and extended filter media life.

At present, we consider sorbent stations to be standard practice in welding fume extraction systems. Their cost is negligible compared with that of filter media, and the benefits are significant. The zeolite dries, degreases, reduces odours and significantly improves filter regeneration.

The sorbent station itself does not capture pollutants; rather, it binds grease and other problematic components using an appropriate sorbent. For instance, zeolite can absorb oil aerosols, dry out dust, and simultaneously reduce odours. This allows the filter media to regenerate more effectively and significantly extends their service life.

The Sorbent Station reduces the negative impact of oily aerosols by binding them to the surface of the sorbent particles. For example, zeolite has a very large internal surface area and porous structure, enabling it to absorb oil components and other sticky substances. Instead of greasy dust, a dry mixture of dust and sorbent enters the filter, which regenerates much more effectively and does not adhere to the filtering media.

The sorbent station generally has a positive impact on the filter’s pressure drop. Zeolite binds fatty aerosols and dries out dust, preventing sticky deposits from forming on the filter media. The resulting dust cake is free-flowing, allowing regeneration to remove it easily. This leads to lower and more stable pressure drop throughout the life of the filter media, along with reduced electrical energy consumption.

For fabric filters, we consider sorption to be one of the best investments. Thanks to it, we are able to maintain the declared service life of filter media for at least 20,000 operating hours, even in problematic welding environments. For cartridge filters, the benefit is significantly lower because the sorbent can accumulate in the narrow pleats of the cartridges and gradually clog them.

Yes. The adsorption station is not tied to a specific filter manufacturer. We routinely install it on competitor equipment as well. If the customer has issues with grease, odours or short filter media life, there is no need to replace the entire filter. In most cases, simply replenishing the adsorbent material resolves the problem.

At a typical welding station with an output of around 30,000 m³/h, we estimate the consumption of approximately one bag of sorbent per week. This translates to costs in the tens of pounds per week. Compared to the replacement of filter media, this is a negligible amount that quickly pays for itself through extended hose life and more stable pressure drop.

Economically, a sorbent station makes sense for welding extraction in almost all cases. The cost of the sorbent is low, but the benefits—such as reduced pressure drop, extended filter media life, and odour control—are significant. Another suitable application is the extraction of fine aluminium dust, where the sorbent helps modify the properties of the captured dust and reduces the risk of forming an explosive mixture.

The main advantage of sorbent stations over frequent filter media replacement is undoubtedly cost. Sorbent costs only a fraction of new filter media and simultaneously helps maintain low pressure drop, reduce odours, and extend filter lifespan. Therefore, in most welding shops, it represents a very quick return on investment.

Sorbent stations are most commonly used in welding shops, where they help mitigate the impact of oil aerosols, extend the lifespan of filter media and reduce odours. A second typical application area is grinding operations and other facilities processing fine explosive dusts, such as aluminium, zinc or magnesium. Here, the sorbent modifies the properties of the captured dust and contributes to enhancing the overall safety of the system.

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Dust extraction for grinding and cutting

Dust generated during grinding must be extracted primarily to protect workers’ health and maintain a clean working environment. In addition to particles from the workpiece, it contains fine dust from abrasive discs that easily spreads throughout the hall and can be inhaled over extended periods. High-quality extraction also reduces dust accumulation on machinery and lowers cleaning requirements.

Grinding metals generates a wide range of particles. Coarser particles have greater mass and usually fall to the ground quickly, posing less health risk. The greatest attention must be paid to fine particles produced by grinding discs and very fine metal dust. These particles remain suspended in the air for long periods, easily enter the respiratory tract, and are the main reason why effective extraction is essential when grinding.

The amount of harmful substances generated during metal cutting depends primarily on the technology used. Cutting with an abrasive disc produces sparks, fine dust, exhaust fumes, and vapours from oil and grease residues on the material surface. In contrast, cutting with a saw blade or band saw generates mainly coarse chips, while the quantity of fine particles is minimal.

When designing grinding extraction systems, it is essential to account for the fact that sparks and dust are dispersed in all directions. Therefore, grinding booths or cabins equipped with L-shaped hoods are most commonly used, as they capture dust and sparks from both the side and rear. This ensures effective extraction without the need for constant repositioning of the extraction components.

The required air flow rate for grinding extraction is typically determined by the length of the extraction edge. As a rule of thumb, we calculate approximately 1,500 m³/h per metre of hood length. A standard grinding workstation features L-shaped extraction walls with dimensions of roughly 2 × 3 metres, resulting in a total extraction edge length of around 5 metres. This implies a required extraction capacity of approximately 7,500 m³/h per workstation.

Grinding dust behaves differently to welding fume. It is generally dry and non-greasy, allowing it to shed very effectively from filter media; consequently, filters operate with lower pressure drop during grinding, and the filter media typically enjoy a longer service life. On the other hand, grinding generates a significant amount of sparks, so we recommend installing a spark separator before the filtration unit to protect the filter media from damage and reduce the risk of fire.

The difference between dry and wet grinding does not lie in the filter itself, but rather in the need to separate emulsion droplets before they enter the ductwork during wet grinding. A small separator located directly at the machine serves this purpose. The emulsion is returned to the machining centre, while the dust continues to the common filtration unit. This allows dry and wet grinding to be combined without issue on a single extraction system.

Manual grinding is most commonly addressed by spatial extraction of the entire workstation using side hoods arranged in an L-shape. During grinding, dust and sparks fly in all directions, making conventional extraction arms less effective here. The L-shaped hoods surround the working area and ensure reliable capture without the need for constant repositioning of the extraction system.

Automatic sanders typically have their dust collection integrated directly into the machine’s design. There is no need to devise special hoods; simply connect the extraction system correctly and adhere to the specified performance ratings. Wide belt sanders are a typical example, where the manufacturer usually knows very well how much airflow is required.

In most cases, deburring machines have dust capture addressed by the machine manufacturer using integrated covers. The role of the extraction system is to correctly connect the flanges and ensure the extraction performance specified by the manufacturer. With a proper design, dust capture efficiency is typically very high, meaning no special solutions are required.

We recommend extracting the dust from vibrating sanders using a high-vacuum system with a narrow hose connected directly to the sander. This captures the dust at its source, meaning operators do not need to manage hoods or extraction arms. The result is a cleaner workspace and significantly less dust escaping into the surrounding area.

Belt sanders typically have dust extraction integrated directly into the machine’s design. As the belt moves, dust and sparks are predominantly carried in one direction, allowing manufacturers to design highly effective built-in extraction systems. The role of the suction supplier is then primarily to correctly connect the flanges and ensure the specified extraction performance.

Bench grinders typically feature a wheel guard with an integrated flange for dust extraction connection. This allows dust to be captured directly at the source with high efficiency. It is important to ensure the correct connection of the extraction ducting and to maintain the required airflow rate. With proper design, most of the dust remains contained within the guard and does not escape into the surrounding environment.

At CNC machining centres, dust is rarely the primary concern; instead, oil aerosols, vapours, and fine emulsion droplets are the main issues. Consequently, standard dust filters are not used. Instead, specialised filtration units designed for aerosol separation are employed. We have had excellent results with ZEOREG zeolite filtration units, which capture aerosols and return the separated liquid back to the machine. This reduces emulsion consumption and improves the working environment.

We extract the plasma directly from the table. We maintain an air velocity of around 20 m/s in the ductwork to prevent dust accumulation. A spark separator is installed upstream of the filter, and the Jet BAG filter has proven itself as the optimal solution. The cleaned air can be recirculated back into the hall during winter via a diverter damper, or exhausted outdoors in summer.

Laser cutting is handled in a very similar way to plasma. Extraction takes place directly from the table; we recommend an airflow velocity of around 20 m/s in the ductwork and install a spark separator before the filtration unit. In practice, Jet BAG fabric filters have proven to be the optimal solution. The cleaned air can be recirculated back into the hall during winter and exhausted outdoors in summer. For lasers with a working area of 1.5 × 3 m, airflow rates typically range around 5,000 m³/h, while larger machines require approximately 8,000 m³/h.

There is no room for compromise with aluminium dust. Extraction must operate at constant performance; the filter must be ATEX-rated and equipped with a B-Flap, pressure relief membranes, and a reinforced structure. We also recommend sorbent dosing, which alters the properties of fine dust and enhances system safety. For these applications, we use Jet BAG and Flat HOUSE filters.

Requirements for extracting metal dust are relatively straightforward compared to welding. It is crucial to capture sparks before they enter the filter, which is why we recommend installing a pre-separation chamber or spark separator. Cloth filters such as the Jet BAG and Flat HOUSE have proven highly effective as filtration units, offering low pressure drop and long media life. The cleaned air can be recirculated back into the hall during winter and exhausted outdoors in summer by switching between summer and winter modes.

Cast iron dust is considered a specific application due to its tendency to adhere to filter media. We therefore recommend designing for lower filtration velocities and larger filter areas to ensure reliable cleaning and extended filter life. A pre-separation chamber for capturing coarser particles is essential, while Jet BAG and Flat HOUSE fabric filters have proven to be the optimal solution in practice. The cleaned air can be recirculated into the hall during winter and exhausted outdoors in summer by switching between seasonal modes.

Grinding tables typically feature a suctioned work surface and a rear canopy, forming an independent and highly efficient workstation. Performance ranges from approximately 2,500 m³/h for one-metre-wide tables up to 5,000 m³/h for tables 2.5 metres wide. We recommend installing a spark separator upstream of the filter and utilise Jet BAG units as the filtration system. Multiple tables can be easily connected to a single central system, allowing heat recovery within the hall by switching between summer and winter modes.

Large grinding stations are most commonly addressed using a central extraction system. Individual workstations are connected to a common duct network, and the extraction capacity is optimised according to the number of active stations via automatic dampers. We recommend installing a spark separator upstream of the filtration unit; in practice, Jet BAG and Flat HOUSE bag filters have proven to be the optimal solution. The cleaned air can be recirculated into the hall during winter months or exhausted outdoors in summer. To reduce noise levels, the fan is typically housed within an acoustic enclosure.

In most cases, the dust extraction for robotic grinding workstations is handled directly by the manufacturer using integrated hoods and covers. The role of the suction supplier is to correctly connect each cell to the central ductwork system and ensure the specified suction performance. To optimise energy consumption, we recommend automatic dampers, spark separators before the filter, and Jet BAG and Flat HOUSE filtration units, which have proven highly effective in practice.

Dust deposition in ductwork can be prevented primarily by maintaining the correct flow velocity. For metallic dusts, we recommend a minimum speed of 20 m/s and design the ducting to ensure that the velocity remains as constant as possible throughout the entire route. Correct step-down sizing of the duct diameters is also crucial. In systems with automatic dampers, airflow velocity may drop when only part of the workstations are in operation. Therefore, we recommend regular duct flushing, where all dampers are opened at defined intervals and the fan operates briefly at maximum power. This removes any deposits and cleans the ductwork.

Dust leakage into the production hall can be prevented primarily through correctly designed primary extraction. However, if fine particles escape into the space, we recommend supplementing the system with secondary extraction featuring continuous performance. This operates continuously and captures dust that has escaped from the main extraction units. The result is a cleaner hall, reduced airborne dust, and an improved working environment.

The most common mistake is relying on extraction arms for grinding dust removal. These have limited reach and are often ignored by workers because they hinder their workflow. Moreover, during grinding, dust and sparks fly in all directions. The result is a mess throughout the hall, leaving customers wondering why the extraction system isn’t working.

Inadequate extraction from the grinding station is easy to identify. If there is a layer of dust around the workstations, deposits on machinery, structures or floors, and workers have to keep cleaning up, something is wrong. Properly designed extraction should capture dust before it enters the hall.

Sparks generated during grinding are not an issue. At the correct air velocity within the ductwork, they extinguish themselves before reaching the filter. Furthermore, a spark separator is installed upstream of the filtration unit, providing an additional layer of safety.

We protect filtration equipment primarily through the correct design of the entire system. The foundation is sufficient flow velocity in the pipework, which ensures that hot particles cool down and extinguish during transport. Another level of protection is provided by a spark separator installed upstream of the filtration unit. In certain applications, safety can be further enhanced by dosing sorbent, which modifies the properties of the captured dust and reduces the risk of forming hazardous mixtures.

The combination of grinding and welding at a single workstation is very common in practice and presents no issues. The entire system is designed according to the more demanding process, which is welding. The filter area, filtration velocity, and regeneration capacity are dimensioned so that the filter can handle welding fumes and oil aerosols. The system includes a sorbent dosing station, which prevents the clogging of filter media, and an spark separator, which protects the filter during grinding. The result is one reliable unit capable of handling both processes without any problems.

Abrasive dust does not harm the filter media but damages the piping. Elbows and branches suffer the most, as they can gradually wear through at high speeds. Therefore, we use reinforced welded pipes, install a coarse pre-separator before the filter, and equip the filter itself with a pre-separation chamber. This ensures everything operates very effectively.

Dust particle size has a fundamental impact on the design of filtration equipment. Coarse particles usually do not pose a problem, as they tend to settle into the hopper under their own weight or are captured in the pre-separation chamber. Consequently, filter design focuses primarily on the fine dust fraction, which tends to remain suspended for extended periods and places the greatest demands on filtration media and regeneration systems.

The extraction of aluminium grinding dust imposes high safety requirements. It is essential to maintain the minimum air velocity in the ducting as per ATEX regulations to prevent dust accumulation. The system must include a B-Flap non-return valve, and the pipework between the filter and the B-Flap must be pressure-resistant to withstand any potential explosion propagation. The filtration unit must be of antistatic construction, fitted with fabric filter media and relief membranes. To enhance safety and modify the properties of fine dust, we recommend installing a sorbent dosing station.

Titanium and other reactive metals require similar extraction considerations to aluminium. Fine dust from these metals can be explosive and, in certain cases, highly reactive. The foundation lies in maintaining the correct air velocity within the ductwork, preventing sediment buildup, utilising ATEX-certified filters, antistatic filter media, B-Flaps, pressure-resistant piping between the filter and the B-Flap, and pressure relief membranes. For these applications, we also recommend sorbent dosing, which helps modify the properties of fine dust and enhance system safety.

We manage several sanding machines with varying levels of operational intensity using a central ducted system. Individual sanders are connected via dampers, and extraction is activated only where actual sanding takes place. The ductwork must be correctly sized according to the capacity of each sander to maintain adequate airflow velocity and prevent dust accumulation. For systems equipped with automatic dampers, we also recommend regular duct flushing by opening all dampers and running the fan at maximum power for a short period.

Filters clogging during grinding is relatively rare. Abrasive dust tends to be dry and fabric filter media have a smooth surface from which the dust detaches very effectively during regeneration. Consequently, pressure drops are usually low and stable. The most common cause of problems is not the filter itself but neglected maintenance, such as an overfilled collection bin or an unemptied bucket, where dust begins to accumulate back into the filtration unit.

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Wood and biomass extraction

Sawdust must be extracted primarily because it is produced in large quantities. Sawdust and fine dust are bulky, fluffy, and accumulate rapidly around machinery. Without effective extraction, manufacturing processes would literally become buried under layers of sawdust, which means not only untidiness but also a significantly increased risk of smouldering and fire. Therefore, extraction in wood-processing facilities is not a matter of comfort, but a fundamental requirement for safe operation.

Wood waste of virtually all types can be extracted, from raw wet sawdust to the finest abrasive dust. However, each application has its own specifics and requires a different approach. Extracting sawdust from solid wood is designed differently from extracting dust generated by sanders, chipboard or MDF panels. The decisive factors are particle size, material moisture content, waste volume and the method of further processing.

Sawdust and fine wood dust behave in completely different ways. Coarse sawdust has a high weight and usually falls spontaneously into the pre-separation chamber and hopper within the filtration unit. Fine wood dust, on the other hand, tends to remain suspended for longer periods and settle between the filter elements. It is precisely this fine fraction of dust that determines the size of the filter, the filtration rate, and the regeneration method.

To design an effective dust extraction system for a woodworking workshop, we need to know the number and type of machines, the size of the suction ports, and their simultaneous operation. The filter location and the investor’s plans for waste disposal are also crucial. Some prefer sawdust to be collected in silos, others in containers, while some produce briquettes. The method of handling waste often determines the configuration of the entire system.

When extracting wood dust, it is not just the total air volume that matters, but primarily the flow velocity within the ductwork. For fine sawdust, a speed of around 20 m/s is usually sufficient. For coarser sawdust, offcuts and small pieces of wood, we recommend speeds between 22 and 24 m/s to prevent material from settling in the pipes. Particular attention should be paid to flexible hoses in the suction section. These have higher pressure losses than rigid piping, so they should be kept as short as possible.

We manage multiple woodworking machines using a central duct system with dampers. Extraction occurs only where the machine is actively operating, and fan power adjusts to current demand. The ductwork must be correctly sized, and the system should feature regular purging cycles to prevent sawdust accumulation. We utilise the Flat WOOD vacuum filter as our filtration unit. Cleaned air can be recirculated into the hall during winter months and exhausted outdoors in summer.

CNC wood machining centres often have high requirements for flow velocity, typically around 30 m/s. This is primarily due to manufacturers’ efforts to reduce the diameter and weight of hoses moving with the machine. However, it is not advisable to maintain such a high velocity throughout the entire piping system, as this would lead to unnecessarily high pressure losses and increased electrical energy consumption. Therefore, we recommend expanding the pipe immediately after connecting to the machine and reducing the flow velocity to approximately 22 m/s. Care must be taken with certain CNC centres that monitor vacuum levels in the extraction system. In such cases, it is essential to comply with the machine manufacturer’s requirements.

Wood sanders, particularly wide-belt sanders, represent a specific application. Unlike sawing, sanding generates very fine dust that tends to remain suspended for extended periods and places higher demands on filtration equipment. Sanding after lacquering is even more demanding due to the ultra-fine dust produced. Consequently, these filters are designed with a larger filtration area and lower filtration velocity than standard chip extraction filters. The entire system must be designed in compliance with ATEX requirements.

Automatic lines for furniture production are most commonly equipped with a central extraction system. Individual machines are connected to a common ductwork fitted with automatic dampers that open only for the active machinery. The system should also include regular duct flushing to prevent sawdust accumulation. A vacuum filter such as the Flat WOOD has proven highly effective as the filtration unit. Collected sawdust is typically conveyed into a silo, and the entire system is designed in an ATEX-compliant configuration. Cleaned air can be recirculated back into the hall during winter months and exhausted outdoors in summer.

Sawdust accumulation in the pipework can be prevented primarily by maintaining sufficient flow velocity. For coarser sawdust and offcuts, we recommend velocities of 22 to 24 m/s. If the system is equipped with power regulation and automatic dampers, it is advisable to regularly flush the pipework by opening all dampers and operating briefly at maximum power. The correct design of the pipework route is also crucial. We use gentle bends and branches with angles of no more than 30°, which minimise sediment buildup and reduce pressure losses.

Blockages in ducting systems within wood processing plants are rarely caused by sawdust; more often, they result from chips, offcuts and other larger pieces of material that should not have entered the extraction system in the first place. These obstructions most commonly occur in flexible hoses or at points where there is a sharp change in flow direction. Therefore, we recommend using the shortest possible hoses, smooth transitions and ensuring machines are correctly adjusted to prevent oversized material from entering the extraction system.

If we need to transport sawdust over distances of tens of metres, we use fan-based pneumatic conveying. For distances of hundreds of metres, blower-based pneumatic conveying becomes more sensible. The most important factor is maintaining a flow velocity of at least 25 m/s; otherwise, the sawdust will begin to settle within the pipework.

Centralised dust extraction in carpentry workshops is most commonly implemented using a shared duct system with automatic dampers that open only for the machines currently in operation. We recommend the Flat WOOD vacuum filter as the filtration unit. Thanks to the double clearance between the filter hoses and the plunge router, reliable chip removal and trouble-free regeneration are ensured even at high material volumes. The cleaned air can be recirculated back into the hall during winter and exhausted outdoors in summer.

The main advantage of centralised wood dust extraction is waste consolidation. All sawdust ends up in one location, from where it can be easily transported to a silo or processed into briquettes. From a long-term perspective, having one filter, one fan, and a single disposal point represents the simplest and most cost-effective solution. A joinery workshop does not just produce goods; it also generates vast quantities of sawdust that must be effectively managed.

The storage of sawdust and wood waste can be managed in several ways, depending on the volume of waste and its intended use. The most common solution involves cylindrical silos equipped with a digging auger, which can be directly connected to the boiler house and serve as fuel stores. Another option is a container integrated into a closed-loop pneumatic conveying system, allowing for easy handling and removal of the waste. Larger facilities also utilise concrete storage bunkers, which are filled using a distributing screw conveyor positioned above the bunker. This fills the entire space progressively from the rear towards the front, ensuring uniform utilisation of the bunker’s volume.

We recommend handling sawdust transport to the silo using pneumatic conveying. Compared with mechanical conveyors such as belt conveyors or elevators, this is a simpler and more cost-effective solution. Typically, a cyclone positioned above the silo suffices to separate the sawdust from the conveying air. We advise routing the pneumatic system in a closed loop so that the air returns to the circuit, thereby avoiding unnecessary heat losses and dust emissions around the silo.

When extracting wood dust, merely capturing sawdust is not enough; it must also be conveyed continuously. If the filter is connected to a pneumatic conveying system, it is essential to ensure uniform dosing of the sawdust to prevent pipe blockages and clogging. A critical situation can occur, for example, when the filter is switched off followed by regeneration, causing a large volume of material to drop into the hopper all at once. Therefore, we use a scraping mill—a hopper with a flat bottom and a rotating arm—which feeds sawdust evenly into a rotary feeder and subsequently into the pneumatic conveying system.

The extraction of pelletising lines has its own specificities. The main source of contamination is the biomass dryer, from which air exits at approximately 60–70 °C with a very low dew point. It is precisely the condensation of water vapour that presents the greatest risk. Therefore, we recommend using an insulated cyclone separator equipped with resistance heating to prevent cooling and subsequent condensation. We generally do not advise using conventional filters in these applications, as the low dew point leads to material adhesion and operational issues.

We handle biomass shredder dust extraction as simply as possible. The material is transported directly to the cyclone separator located above the silo using a transport fan. We design the entire system so that no additional filtration equipment is required downstream of the cyclone, thereby reducing both capital and operational costs while ensuring high reliability.

Biomass boiler extraction differs from standard dust extraction. The pollution source consists of flue gases from the boiler containing fine fly ash. For these applications, we have developed the Ceramic JET and Steel JET filtration units, which utilise non-combustible filter elements and automatic regeneration using compressed air. This enables solid particulate emissions to be kept below 2 mg/m³ TSP and ensures long-term reliable operation even at high temperatures.

Biomass storage is not just about dust extraction but primarily about removing moisture from the storage area. Biomass naturally contains water, and its storage can lead to increased air humidity. Therefore, the extraction system must help keep the space dry and prevent condensation. We recommend thermally insulating the ductwork as well as the filtration or separation components of the system, particularly for winter operation when the risk of condensation is highest.

Large volumes of sawdust and wood chips must be managed as material handling rather than merely dust filtration. We employ filtration units equipped with flat-bottomed hoppers and a digging auger, which ensures the steady metering of material into subsequent conveying systems. The sawdust or chips are then pneumatically conveyed to a large-capacity silo. This prevents system blockages, allowing the entire operation to run automatically without constant operator intervention.

Adhesion of moist material can be minimised primarily by ensuring the correct air velocity within the pipework and preventing condensation. We recommend maintaining a minimum speed of 22 to 24 m/s to prevent material deposition and ensure reliable transport through to the filter or separator. Thermal insulation of the filtration unit or cyclone separator is equally important, as it prevents cooling of the airstream and subsequent condensation of water vapour, particularly during winter months.

Wet sawdust is handled differently from standard woodworking dust extraction. Typical applications include planers, jointers, or other machinery for processing raw logs. Due to the high moisture content of the material, we typically do not use filtration systems here; instead, a transport fan conveys the sawdust directly into a cyclone separator. A rotary feeder is positioned beneath the cyclone, and the material is subsequently transported into a concrete bunker via a distributing screw conveyor, which fills the hopper progressively along its entire length.

The extraction of wood-based materials, such as MDF, HDF or particle boards, is most commonly addressed by a central duct system with the Flat WOOD vacuum filtration unit. The fine dust from these materials places higher demands on filtration; therefore, we use double spacing between filter elements and a flat-bottomed discharge hopper equipped with a scraping auger to ensure continuous material removal. The entire system is designed in an ATEX version, and the cleaned air can be returned back into the hall during winter or exhausted outdoors during summer by switching between the summer/winter modes.

Light and fibrous powders represent a specific group of materials due to their tendency to interlock and form what is known as a “blanket” within the filter. If there are baffles, supports, or other areas inside the filtration unit where material can accumulate, these components gradually become clogged and lose functionality. Therefore, the internal space of the filter should be as simple and unobstructed as possible. For reliable discharge of the material, we recommend a hopper with a flat bottom equipped with a rotary cutter and a rotary feeder, which ensure smooth removal of fibrous material.

The extraction systems for briquette production lines share similar characteristics with pellet plants. The main issue typically lies with the biomass dryer, which generates air with a low dew point. If the temperature drops below this dew point, condensation occurs and the material begins to stick. Therefore, we recommend using thermally insulated cyclone separators, optionally supplemented by resistance heating. Conventional filtration units are generally not advised for these applications. We utilise transport fans and pressurised cyclone separators, all of which are thermally insulated and heated.

Reliable extraction in the woodworking industry can be significantly enhanced by selecting the right system design. We advise against pressurised systems where material passes through the fan impeller, as these are a frequent source of breakdowns, increased wear and higher electrical energy consumption. For this reason, we prefer vacuum systems with Flat WOOD filtration units. Other critical areas often involve hoppers, where sawdust forms arches, and pneumatic conveying, which can become blocked due to uneven feeding. We address these issues by using flat-bottomed hoppers, rotary feeders and smooth material dosing into the pneumatic system.

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Exhaust gas filtration

Exhaust from furnaces and boilers must be filtered not only to comply with legislation but primarily due to the surrounding operational environment. Smoke rising from chimneys is visible, and fine dust particles subsequently settle in the vicinity. Typical examples include white window sills, parked cars, or laundry hanging on a line. It is precisely this fine soot that often prompts local residents to begin complaining.

The flue gases from boilers and furnaces primarily contain solid pollutants (fly ash), unburned carbon particles, soot, and depending on the fuel type, also sulphur dioxide (SO₂), nitrogen oxides (NOx), carbon monoxide (CO), hydrogen chloride (HCl) and other gaseous components. In biomass combustion, the main issue is fine fly ash, which is very light and would escape up the chimney into the surrounding area without filtration.

To design an effective flue gas filtration system, we primarily require the volumetric flow rate and temperature of the exhaust gases. Based on these parameters, we determine the appropriate filter area, material specifications, and type of filter elements. For such applications, we utilise Ceramic JET or Steel JET filters, which are engineered for high temperatures, fine fly ash, and automatic regeneration using compressed air. This is not an experimental approach but a solution proven across numerous successful installations.

When designing flue gas filtration systems, the most critical factors are knowing what fuel is being burned, the boiler or furnace output, the volume of flue gases produced, and their temperature. These parameters determine the size of the filtration unit, the type of filter elements required, and the material specifications. Filtration for biomass differs significantly from that for coal, melting furnaces, or industrial process exhaust gases.

The flue gas temperature has a significant impact on the design of filtration equipment. As the temperature rises, the dynamic viscosity of the flue gas increases, affecting both flow and air permeability through the filter medium. Therefore, it is necessary to reduce the loading on the filtering surface as the temperature increases and to design larger filters. The temperature also determines the choice of filter elements and the material construction of the filter housing, ensuring long service life and safe operation.

The amount of dust has surprisingly little impact on the size of the flue gas filtration unit. Flue gas filters are inherently designed for very low filtration velocities, and most combustion sources do not exhibit significant differences in particulate concentration. Consequently, the decisive parameters are primarily the volume of flue gases and their temperature, rather than the dust concentration itself.

Exhaust gas humidity has a fundamental impact on filter operation. The most critical conditions occur during the commissioning of the technology or when operating with sub-cooled exhaust gases. If the temperature drops below the dew point, water vapour condenses, leading to the formation of tar deposits that can cause filter elements to become clogged and result in operational issues. Therefore, it is essential to protect the filter, for example by using a bypass to prevent cold exhaust gases from passing through the filter, or by dosing an appropriate sorbent to reduce condensation and the formation of sticky deposits.

Fluctuations in flue gas flow are most commonly addressed using a variable frequency drive, which smoothly regulates the speed of the fan located downstream of the filter. The control system maintains a slight vacuum at the filter inlet, ensuring stable operation of the filtration unit and constant conditions for the combustion source. This simultaneously reduces electrical energy consumption and minimises stress on the entire system.

Fluctuations in flue gas temperature are an inherent part of operation, and filtration systems must be capable of managing them. The greatest risk does not lie in high temperatures, but rather in low temperatures, where the flue gas may cool below its dew point. This leads to water vapour condensation, the formation of tar deposits, and the gradual clogging of filter elements. In such conditions, we recommend applying a suitable sorbent to help maintain the filter in an operational state and reduce the formation of sticky residues.

The difference between filtering cold and hot flue gases lies not so much in temperature but primarily in moisture content and the risk of condensation. Cold flue gases, such as those from electric furnaces, hardly increase humidity and can be filtered very effectively without thermal insulation or other measures. In contrast, flue gases from boilers and combustion processes contain water vapour, with their greatest risk being condensation and subsequent tar formation. It is therefore necessary to prevent the cooling of flue gases and often address thermal insulation, bypass systems, or sorbent dosing.

The most common sources of exhaust gases in industry are metal processing furnaces and industrial boiler houses. In steelworks and foundries, these are primarily electric and gas-fired furnaces, including both melting and holding types. Another significant category comprises biomass boilers burning materials such as wood chips, pellets, or straw. Each of these sources produces flue gases with different compositions, temperatures, and dust levels, necessitating a bespoke filter system design.

Flue gas filtration for biomass boilers is addressed using high-temperature Ceramic JET or Steel JET filters. These units are specifically designed for this application, employing non-combustible filter elements, automatic pressure air regeneration, and robust long-term operation with biomass flue gases. For the design phase, we primarily require two key parameters: the volume of flue gas and its temperature. The remainder will be tailored to the specific boiler model and required emission limits.

We recommend addressing exhaust gases from melting furnaces using stainless steel components, ideally for both the ductwork and the filter itself. If the exhaust gas temperature is approximately 200 °C or lower, a Jet BAG fabric filter with top inlet and downward flow within the housing can be used. The entire system should be thermally insulated to prevent condensation. The solution may also include dosing Ca(OH)₂ sorbent, which helps reduce sulphur, HF, and HCl content in the exhaust gases.

Exhaust gas from asphalt plants is treated using the Jet BAG filtration unit with a large pre-separation chamber. We recommend directing the exhaust inlet from above and ensuring downward airflow within the filter to separate coarser particles before they reach the filtering media. The entire filter and piping system must be thermally insulated to prevent condensation and material adhesion.

Condensation within the filtration unit must be prevented at all costs, as condensate is typically the primary cause of filter element clogging and tar deposits. The key is to maintain the flue gas operating temperature above the condensation point, ideally between 120 and 150 °C. We recommend dosing a sorbent during system startup to mitigate the adverse effects of moisture. Thermal insulation of the entire system is standard practice, with electrical heating of the pipework or filtration unit also employed in critical applications.

Maintaining flue gas temperatures above the dew point is essential for reliable operation of the filtration system. If the temperature drops below the dew point, water vapour present in the exhaust gases begins to condense. The resulting condensate combines with dust particles, leading to the formation of sticky tar deposits. These can cause filter elements to become clogged, increase pressure drop, and in extreme cases, result in a complete shutdown of the plant.

Condensation in flue gases is one of the most common causes of issues with high-temperature filters. The resulting condensate leads to dust particles adhering to filter elements, formation of tar deposits, blockage of the discharge hopper, and loss of flowability of the collected material. This results in increased pressure drop and a gradual reduction in the filter’s regeneration capability. If left unaddressed, this can ultimately lead to the shutdown of the entire system.

Dust adhesion on filter media is most commonly caused by the presence of moisture, tar or oily components. A highly effective solution is the dosing of an adsorbent, such as ground zeolite. This binds moisture and sticky components, dries the captured dust and improves its flowability. As a result, dust is released more easily from filter elements during regeneration, pressure drop remains low and the service life of the filter is significantly extended.

The most common cause of filter blockage during flue gas filtration is not the dust itself, but rather low flue gas temperatures and subsequent condensation. Water and tar components lead to clogging of the filter elements and a loss of regeneration capability. Another frequent issue is improperly set filter regeneration or unsuitable upward flue gas flow, where particulates remain suspended and unnecessarily burden the filter media.

An undersized filtration system most often manifests as high pressure drop. The filter operates continuously at, for example, 3,000 Pa, the fan runs at maximum speed, yet the extraction capacity gradually declines. The result is reduced dust capture efficiency, higher electrical energy consumption, and increased strain on the entire system.

High dust concentrations primarily lead to an increase in pressure drop due to the formation of a thicker filter cake on the filter elements. The dust itself is generally not problematic if the system is correctly designed. However, issues can arise at the discharge point where under-sized rotary feeder capacity causes material accumulation and subsequent blockage of the hopper cones. Therefore, it is essential to design not only sufficient filtration area but also an adequate capacity for the system that removes the collected dust.

Abrasive dust in flue gas usually does not pose a significant problem. Flue ducts and filtration equipment are typically designed using thick-walled materials, and flow velocities are relatively low compared to pneumatic conveying of dust. Consequently, wear is rarely evident in practice and is generally negligible.

Sparks and hot particles in the exhaust gases are managed by using non-combustible filter materials. The Ceramic JET and Steel JET filters utilise ceramic or metal filter elements that are resistant to high temperatures and hot particles, so there is no need to worry about sparks. Conversely, we do not recommend introducing cold air to cool down the exhaust gases. Additional oxygen can cause the hot particles to reignite, creating a greater problem than it was intended to solve.

The service life of the filtration system during flue gas filtration can be significantly extended through proper design and operation. The foundation lies in a sufficiently large filter area, which enables low filtration velocities and minimal pressure drop. Another crucial element is sorbent dosing, which reduces condensation, tarring, and dust adhesion to the filter elements. Equally important is the correct setting of regeneration to ensure that filter elements are cleaned effectively without suffering unnecessary damage from excessive compressed air pulses.

Large volumes of flue gas are not managed by a single massive filter, but rather by dividing the filtration equipment into several independent modules. The individual modules are separated by isolation dampers, allowing for independent operation and maintenance. The size of each module is chosen to ensure it remains transportable by standard trucks. Thanks to this modular design, filtration systems of virtually any capacity can be assembled in this manner.

The most common error in flue gas filtration design is incorrect handling of the flue gas volume. Suppliers often confuse normal cubic metres (Nm³/h) with the actual volumetric flow rate at operating temperature (m³/h). High flue gas temperatures cause a significant increase in volume, and if this difference is not accounted for, the result is an undersized filter with high pressure drop, insufficient service life, and regeneration issues.

Modernising older flue gas filters is technically quite demanding and therefore not carried out very often. However, if the filter housing is in good condition, it is possible to install new filter elements and modify the original technology, for example by switching to stainless steel or ceramic filters. This can significantly extend the equipment’s lifespan and achieve better emission parameters without the need to construct a new filter.

Yes, an electrostatic precipitator can often be replaced by a fabric filter. This is primarily due to requirements for lower residual particulate matter emissions, which are more easily achieved using modern ceramic or metal filtration elements. However, simply replacing the filter is usually insufficient. Electrostatic precipitators operate with very low pressure drop, whereas fabric, ceramic, or metal filters have significantly higher pressure drops. Therefore, in most cases, it is also necessary to replace or modify the flue gas fan.

Bag filters for flue gas filtration are primarily suitable for melting furnaces and other gaseous or electric heat sources, where the flue gas temperature does not exceed approximately 200 °C. In these applications, Jet BAG filters with top entry and downward internal flow have proven highly effective. Due to low moisture content and the absence of hot particles, they achieve long service life and very low emissions. Conversely, we do not recommend bag filters for biomass boilers. Because of incomplete combustion, hot particles, and fluctuations in operating conditions, non-combustible ceramic or metallic filter elements are more suitable.

Dust levels in flue gas filtration are less critical than in standard industrial extraction systems. Flue gas filters are inherently designed with large filter areas and low filtration velocities. This enables them to handle higher dust concentrations without significantly affecting performance. Consequently, the size of a flue gas filter is determined primarily by the volume of exhaust gases and their temperature, rather than solely by the amount of dust.

Flue gas filtration units are typically installed outdoors rather than within the boiler house. This simplifies the structural design, operation and any potential maintenance, while also freeing up space inside the plant. For smaller installations, typically boilers with outputs of around 1,000 kW, it is possible to locate the filter directly within the boiler house, provided that spatial constraints and local regulations permit this.

The service life of filter media during flue gas filtration can be significantly extended through proper system design and operation. We achieve very good results using sorption, which reduces dust adhesion and the formation of tar deposits. Equally important are as constant operating conditions as possible, a sufficiently large filtering area, and correctly set regeneration. The combination of these measures enables long service life for filter elements and consistently low pressure drops.

Flue gas filtration is most commonly used by foundries and melting plants for ferrous and non-ferrous metals, such as aluminium, copper or glass. A significant group also includes biomass boilers burning wood chips, pellets or straw. Each of these operations has specific requirements regarding temperature, flue gas volume and dust composition, thus requiring an individual design of the filtration system.

The efficiency of flue gas dedusting can be significantly improved by replacing or supplementing the cyclone separator with filtration equipment. In many older boiler houses and furnaces, standalone cyclones are still in operation; these have relatively low efficiency and are unable to capture fine dust particles. By installing a filter, emissions of solid pollutants can be reduced to single-digit mg/m³ levels, effectively eliminating visible smoke and issues related to dust deposition around the facility.

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High temperatures

High-temperature filtration generally refers to applications where gas temperatures exceed the capabilities of standard polyester filter media. Typically, this involves temperatures above 150 °C, at which point conventional textile media can no longer be used and special materials such as meta-aramid media, ceramic filter candles or microporous stainless steel filter elements must be selected.

For textile filters, standard operating temperatures reach approximately 150°C, where polyester filter media are most commonly used. By employing specialised materials such as meta-aramid, it is possible to filter gases at temperatures around 200°C on a long-term basis. For higher temperatures, ceramic or microporous stainless steel filter elements must be used.

The design of high-temperature filtration begins with a thorough understanding of the process itself. It is essential to know the volume of extracted air or flue gas, the operating temperature, and crucially, whether the stream contains sparks, hot particles, or unburnt residues. These parameters determine the choice of filter media type—specialist textiles, ceramic filter candles, or microporous stainless steel capsules.

High temperatures pose several risks to the filtration system. They can accelerate the ageing of filter media, cause damage or even complete destruction if the maximum operating temperature is exceeded. Other issues include thermal expansion of pipes and structures, changes in material properties, condensation when flue gas cools below the dew point, and, in some cases, the presence of sparks or incomplete combustion.

Temperature has a significant impact on the size of filtration equipment. As temperature rises, gas volume increases; therefore, the filter must have a larger filtration area and greater flow cross-sections. At the same time, the dynamic viscosity of gases increases, leading to higher pressure losses as the gas passes through the filter medium and dust cake. These factors need to be taken into account during the design phase of both the filter and the fan.

Temperature also has a significant impact on the fan. As temperature rises, air density decreases; therefore, a different fan design is required for the same volumetric flow rate compared to cold air. At the same time, it is necessary to account for the increased thermal stress on bearings, shafts, and impellers. High-temperature fans often feature a rotor directly mounted on a separate shaft and are typically equipped with thermal insulation or motor separation from the flowing medium.

Temperature spikes can have a significant impact on the filtration system and must be accounted for during the design phase. The filter medium and other components must be capable of safely withstanding short-term temperature increases. If temperature spikes exceed the resistance of the selected medium, damage may occur or its service life may be significantly reduced.

Fluctuations in flue gas temperature are an inherent aspect of many industrial processes, and the filtration system must be designed to accommodate them. Consequently, filter design must account not only for standard operating temperatures but also for temperature peaks and the potential for condensation. To protect equipment, measures such as thermal insulation, hopper heating, and other safeguards are employed to prevent temperatures from falling below the dew point.

Exceeding the maximum operating temperature must be addressed during equipment design. In certain applications, drawing in ambient air can cool exhaust gases to the required temperature. However, this solution is not suitable for all processes. For instance, in boilers or combustion units, introducing oxygen may cause afterburning of unburnt fuel and pose a serious fire hazard.

Protection against sudden temperature spikes begins with the correct choice of filter media. If the process exhibits temperature peaks or the presence of sparks and unburnt residues, it is essential to use materials that can safely withstand these conditions. For the most demanding applications, ceramic filter candles or microporous stainless steel filter elements are employed, offering high thermal resistance and a long service life.

Flue gas cooling is required when the temperature exceeds the maximum permissible limit for the filter medium or other components of the technology. Simultaneously, cooling the flue gases can be economically advantageous, as lower temperatures reduce gas volume, thereby decreasing the size of the filter, fan, and ductwork. In some cases, thermal energy can also be utilised for further process applications. The disadvantage is the higher capital investment required for the overall solution.

The exhaust gas cooler operates on the principle of heat exchange between hot flue gases and ambient air. The gases flow across the heat transfer surface, where they are cooled in a controlled manner. The required cooling capacity is typically regulated by adjusting fan speeds, ensuring that the outlet temperature of the flue gases remains stable even under varying operational conditions. An important aspect is the provision for regeneration, i.e., automatic cleaning of the inner side of the tube bundles from deposits and fouling.

Cold air mixing is employed when it is necessary to reduce flue gas temperatures to a level safe for the filtration system. This solution is particularly suitable for processes where an increase in oxygen content poses no risk. A typical example is the extraction of gases from melting furnaces, where drawing in ambient air does not cause ignition or afterburning of the exhaust gases.

The main advantage of an exhaust gas cooler compared to drawing in ambient air is that it cools the exhaust gases without diluting them. As the temperature drops, the volume of the gases decreases, allowing for smaller filters, fans, and ductwork. At the same time, part of the thermal energy can be utilised for further process purposes. The disadvantage is the higher capital investment required for the entire system.

At high temperatures, thermal expansion of the piping occurs and material stress increases. It is therefore essential to select materials and wall thicknesses that can withstand operating temperatures over the long term while maintaining sufficient strength. Thermal expansions must also be accounted for; compensators and an appropriate support system should be used for longer runs.

Thermal expansion of pipework is managed using compensators. These allow the piping to safely change length during heating and cooling cycles, without transferring forces to the filter, fan or supporting structure. For long runs and high-temperature applications, compensators are practically essential.

Fans for high-temperature applications must be designed to withstand long-term operation at elevated temperatures. Key considerations include thermal insulation, protection of bearings and the motor from radiant heat, and an appropriate rotor design. A common approach is to mount the rotor on a separate shaft and incorporate cooling discs, which reduce thermal stress on the bearings and extend their service life.

The insulation of the pipework and filter must be carried out thoroughly, ensuring there are no thermal bridges. Any uninsulated area poses a risk of flue gas temperatures dropping below the dew point, leading to condensation. This can cause the filtering media to become clogged, result in equipment corrosion, and create issues with ash discharge. Therefore, correct thermal insulation is an essential component of reliable operation for high-temperature filtration systems.

Condensation during flue gas cooling cannot be entirely prevented, as it is a physical phenomenon associated with exceeding the dew point. However, its occurrence can be significantly reduced through proper system design. The foundation lies in high-quality thermal insulation of the pipework and filter, minimisation of thermal bridges, and, where necessary, heating of hoppers or other critical components of the equipment.

The dew point is one of the most critical parameters in hot gas filtration. If the gas temperature drops below the dew point at any point within the system, condensation of water vapour or aggressive components will occur. This can lead to blinding of the filter media, corrosion of the pipework and filter, issues with ash discharge, and a significant reduction in the overall lifespan of the equipment.

Flue gas filtration at temperatures up to 200°C is often achieved using a fabric filter with a meta-aramid filter medium. This solution is particularly suitable for stable processes without the risk of sparks or incomplete combustion. However, if dealing with a boiler or other combustion source where incomplete combustion may occur, we recommend using non-combustible filter elements, such as ceramic or metal ones, even at temperatures up to 200°C.

We no longer address flue gas filtration above 250 °C using textile filters. For these temperatures, we use ceramic filter candles or microporous stainless steel filter elements from Steel JET. Both solutions are non-flammable, resistant to high temperatures, and suitable for applications where sparks or unburnt particles may occur.

Ceramic filters are particularly suitable for filtering hot flue gases containing sparks or unburnt particles. Ceramic filter candles are non-flammable and their surface is not damaged by the impact of hot particles. Thanks to their high temperature resistance and mechanical stability, they are an ideal solution for demanding applications where standard textile media could be damaged or completely destroyed.

Metal filters are primarily suitable for high-temperature flue gas filtration where sparks or unburnt particles are present. The microporous stainless steel filter elements are non-combustible, resistant to high temperatures, and their surface is not damaged by the impact of hot particles. Consequently, they are ideal for demanding industrial applications where standard textile media would be unable to ensure sufficient service life and operational safety.

Ceramic filter elements are distinguished by their high thermal resistance, non-flammability, and resilience against sparks and incomplete combustion. Unlike textile media, their surface is not damaged by the impact of hot particles, enabling safe and long-term operation even in the most demanding applications. They are therefore particularly suitable for filtering flue gases from boilers, melting furnaces, and other high-temperature processes.

Metallic filter elements offer high temperature resistance, non-flammability and the potential for very compact filter designs. Because flat filter bags are manufactured from microporous stainless steel fabric, a large filtration area can be accommodated within a relatively small space. Metallic elements also allow horizontal installation and top-down filtration, which significantly reduces dust re-entrainment inside the filter and improves the discharge of collected material.

One of the most common errors in hot gas filtration is underestimating the actual volume of flue gases and designing the filter area incorrectly. A frequent mistake is confusing normalised volume (Nm³/h) with operating volume at actual temperature, which results in undersized filters. Another overlooked factor is the effect of dynamic gas viscosity, which increases the pressure drop across the filter medium and dust cake as temperature rises.

The lifespan of a high-temperature filtration system can be significantly extended through proper design and stable operation. It is important to minimise thermal shocks, prevent condensation, and select the appropriate filter medium. Dosing sorbents, such as zeolite, which helps reduce moisture levels and limits the blinding of filter elements, is also a highly effective measure.

Older high-temperature filtration systems can often be successfully upgraded. The key is to assess the technical condition of the filter housing and supporting structure. If these are in good condition, there is no need to replace the entire system. Instead, a retrofit can be carried out by installing modern ceramic filter candles or microporous stainless steel elements from Steel JET. This significantly extends the equipment’s lifespan and improves its operational performance.

Textile filter media have their limits primarily in maximum operating temperature, spark resistance and chemical resistance. Standard polyester media are commonly used up to 150 °C, while special materials such as meta-aramid can withstand temperatures of approximately 200 °C. Above these temperatures or in applications involving incomplete combustion and hot particles, ceramic or metal filter elements must be used.

If the filtration system is correctly designed for the specified temperature, the filter itself does not suffer from high temperatures. The fan is more likely to be the critical component. If the design temperature is exceeded, gas density decreases, the fan’s operating point shifts, and this can lead to motor overload or, conversely, insufficient performance. Therefore, it is important to design the entire system with adequate thermal reserve.

Frequent temperature fluctuations pose mechanical stress to the filtration system primarily due to thermal expansion of individual components. Pipes, filters and fans constantly expand and contract during heating and cooling cycles, which can lead to increased strain on joints, compensators and the structure itself. Therefore, these changes must be accounted for already at the design stage of the equipment.

Protection of filtration equipment against emergency overheating primarily involves using filter elements capable of withstanding extreme temperatures for short periods. In some applications, temperature monitoring, automatic shutdown of the technology, or emergency intake of cold air are employed. However, the design of protection always depends on the specific process and its associated risks.

High temperature itself does not hinder filter regeneration if the filter medium is correctly designed for that specific temperature. On the contrary, at higher temperatures, dust is often drier and regeneration can be highly effective. Problems arise only with condensation, the presence of oily components, or when exceeding the temperature limits of the filter medium.

Thermal protection against overheating must be designed according to the specific process. The foundation lies in selecting a filtration medium with adequate temperature reserve. Additional layers of protection may include temperature monitoring, automatic shutdown of the technology, emergency intake of cold air, or the use of non-combustible filter elements. The objective is to ensure that neither damage to the filter nor fire occurs even under exceptional conditions.

All components of the filtration system that come into contact with hot gases must be adapted to high temperatures. It is not sufficient to select only a suitable filter medium. The filter housing, ductwork, fan, compensators, seals, dampers, measuring devices, and thermal insulation must also possess adequate temperature resistance. The entire system must be designed as a single functional unit.

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Solid Alternative Fuels (SAF)

Dust from solid alternative fuels (SAF) is characterised primarily by its highly heterogeneous structure and variable composition. It contains fine dust alongside light and problematic fractions such as plastics, polythene bags, films, paper, textiles, tapes, or remnants of packaging materials, often supplemented with fly ash and mineral particles. This combination causes the dust to become electrostatically charged, form sticky clumps, and significantly degrade its flow properties, leading to an increased risk of bridging in filters, hoppers, and pipework. From a safety perspective, it is crucial that the fine fraction may be explosive (ATEX risk), while coarser particles can cause mechanical issues and block filter elements. Overall, this is very “light, sticky and irregular” dust, which requires specific design for extraction and filtration.

Yes, we have experience in extracting dust from solid alternative fuels (SRF), including the design and implementation of extraction systems for SRF sorting plants, SRF storage facilities, pneumatic transport, and local transfer points. These operations are characterised by high dust levels, variable material fractions, and risks of blockages and dust explosions; therefore, correct sizing of the extraction system, appropriate filtration, and stable regeneration control are essential to ensure reliable performance even under demanding conditions.

The central filter for solid alternative fuels (SAF) is distinctive primarily due to its construction, which must account for highly problematic and heterogeneous material. It typically features larger spacing between filtering elements to minimise blockages and the deposition of light fractions, alongside a robust regeneration system because dust tends to adhere and form crusts. The filter base is often designed as a flat or inclined hopper equipped with a scraper milling tool and a large rotary feeder, ensuring continuous material discharge. The design incorporates minimal internal stiffeners and horizontal surfaces, as these promote bridging and material accumulation. Ultimately, the objective of the design is to minimise areas where SAF material could become trapped; otherwise, rapid blockages and operational failures occur.

Yes, the heterogeneous material from TAP can be effectively separated into two fractions by installing a rotary separator upstream of the filter. The coarser fraction (above approx. 5 mm) is discharged from the separator and returned to the belt for recirculation within the process, while the fine dust fraction from the filter is conveyed to the briquetting press, where it is compacted into briquettes and subsequently reintroduced into the technological process. This significantly improves material utilisation, stabilises filtration operations, and reduces issues with arching and system blockages.

Yes, solid alternative fuels can typically be dedusted using local filters, particularly at locations such as receiving stations, conveyor belt transfer points or material transfer points. Local JET filters with capacities of around 2,000 m³/h are commonly used; these are designed to capture fine dust locally directly at the source to prevent its dispersion into the surrounding area. In these applications, designs featuring larger spacing between filter elements, double gaps between bags and regeneration using compressed air have proven effective, as TAP dust tends to adhere and bridge.

Yes, for the end points of pneumatic conveying of solid alternative fuels (SAF), we offer a solution in the form of cyclone filters. These combine centrifugal separation and fine filtration within a single unit and are specifically designed for this type of application. Typically, they consist of a large cylindrical cyclone with an internal Hardox lining to enhance abrasion resistance, followed by a filter section featuring pockets with wider spacing and ATEX certification, including a pressure-relief membrane for safe operation. The captured material is then discharged into a hermetic storage hopper either gravitationally or via a rotary valve (airlock), ensuring reliable and sealed material discharge without dust leakage. This type of solution is highly suitable in practice for the pneumatic conveying of SAF, where it is necessary to combine high durability, safety, and stable separation of fine fractions within a single piece of equipment.

The extraction of dust from solid alternative fuel (SAF) sorting facilities is typically implemented as a central vacuum system designed to handle high dust loads, heterogeneous materials, and the risks of bridging or dust explosivity. Extraction takes place at individual sources using suction hoods, with airflow regulated by control dampers to ensure stable vacuum levels throughout the system and uniform extraction across all process points. The air is conveyed via central pipework to a filtration unit, which is usually ATEX-certified, featuring large clearances between filter elements and robust pulse-jet cleaning, as SAF dust tends to be sticky and prone to clogging. The filter is typically equipped with a flat discharge hopper and a scraper mechanism to ensure continuous material removal, with the discharged material transferred via a rotary airlock feeder for further processing. Radial fans are most commonly used, discharging the cleaned air back into the sorting hall.

Suction systems in solid alternative fuel (SAF) warehouses are typically designed as low-pressure systems, aiming to achieve approximately 2–3 air changes per hour. This is because the primary objective extends beyond dust control to include moisture extraction, vapour removal, and maintaining a stable microclimate within the facility. Extraction is most commonly implemented near the ceiling, where light, dusty, and moist fractions accumulate. It is crucial to ensure uniform airflow throughout the entire warehouse space. Ductwork is often insulated to prevent condensation and subsequent blockages within the system. The filtration unit is usually designed with standard filter element spacing, as larger mechanical debris such as plastic bags or coarse fragments are typically absent from the ceiling extraction zone. Ultimately, the goal is to ensure consistent removal of moist and dusty air without risking condensation or sedimentation.

Dust extraction during the transport and handling of solid alternative fuels (SAF) is typically addressed locally at the source of dust generation, particularly on belt conveyor transfer points where compact Local JET type local filters are employed. These units are engineered for high dust loads and heterogeneous materials, featuring wider spacing between filter elements (double gaps) to prevent bridging in the inter-element space. Regeneration is carried out using compressed air. The filter operates without a conventional hopper; instead, captured material is returned directly to the belt, thereby minimising both material loss and the risk of bridging. This solution is highly effective for continuous SAF transport, as it maintains dust control at source without requiring any pipework.

The explosion risks associated with solid alternative fuels (SAF) in processing facilities are highly specific due to the significant variability of the material, which may contain fine combustible dust, plastics, paper, and other organic components. This fine dust can become explosive (ATEX) under certain conditions, particularly when dispersed in air, an ignition source is present, and a confined space with sufficient concentration is formed. In practice, it is not possible to rely on a stable material composition for SAF, as it can vary from day to day and batch to batch. Therefore, technology design must always incorporate safety margins and assume the worst-case scenario. Consequently, such facilities are typically designed with ATEX zones, appropriate explosion relief measures, anti-static construction, earthing, and correctly engineered filtration and material handling systems. The objective is consistently to ensure system safety even if dust properties deteriorate compared to standard operating conditions.

Filtration systems for facilities using solid alternative fuels (SAF) are designed similarly to other industrial systems, but with significantly greater emphasis on material variability, dust generation, and safety risks. The foundation lies in identifying all emission sources within the process—such as crushers, screens, separators, belt transfer points, and material handling locations—and subsequently determining the required extraction capacities for each point.

Based on this analysis, a central extraction system is designed with sufficient performance headroom, connected to a filtration unit. For SAF applications, this unit is typically robust and ATEX-certified, featuring large spacing between filter elements to minimise clogging and ensure effective regeneration. The design also includes correctly sized compressed air regeneration, a flat discharge hopper equipped with a rotary cutter for material removal—often via a rotary feeder—and the placement of the fan on the clean side of the system to protect it.

The entire design must account for the variable composition of SAF, the risk of bridging, abrasiveness, and inherent ATEX hazards. Therefore, it is always designed with both safety and performance margins to ensure stable operation even when the input material changes.

For sorting plants handling solid alternative fuels (SAF), robust Flat WOOD type filters are most commonly used. These feature larger spacing between filter elements (double gaps) and are designed for high dust loads, heterogeneous materials, and the risk of bridging, typically in combination with a hopper, a digging arm, and controlled material discharge.

Conversely, SAF storage facilities utilise simpler Jet BAG type filters. These have standard filter bag spacing, an upper (top-down) air inlet, and are intended for finer dust and more stable operating conditions without coarse fractions, as extraction takes place in the overhead space where coarse material does not accumulate.

Overall, sorting plants require robust “process” filters with higher resistance to clogging, whereas SAF storage facilities are typically addressed using standard dust filtration systems focused on air exchange and moisture removal from the warehouse.

Preventing dust deposition in TAP pipelines is primarily addressed through the correct design of flow velocity and pipeline routing. It is important to maintain a transport speed within the range of 20 to 22 m/s, as lower speeds lead to the sedimentation of fine and light fractions and gradual blockage of the pipes. It is also crucial to minimise pressure losses and turbulence by designing bends with large radii, ideally at least 1.5D, to prevent flow separation and material accumulation in the curves. Pipeline networks should be as smooth as possible, avoiding unnecessary kinks. In TAP systems, thermal insulation is often added to limit moisture condensation, thereby reducing the risk of material adhesion and bridging within the pipes.

For the suction of solid alternative fuels (SAF), it is generally recommended to maintain pipeline transport velocities at approximately 20–22 m/s. This speed is crucial for ensuring stable transport of heterogeneous material, as lower speeds risk the settling of fine and light fractions and the formation of blockages within the pipes. Conversely, excessively high velocities above this range can increase pressure losses, energy consumption, and wear on the pipework. Therefore, an optimally selected velocity represents a compromise between reliable material transport and long-term economical system operation.

Material moisture has a fundamental impact on the entire system when extracting solid alternative fuels (SAF), as it increases the risk of condensation, clogging, and bridging in both the pipework and the filter. As moist air cools within the system, water condenses, leading to dust adhering to the walls, impaired regeneration of the filtration media, and a progressive rise in pressure drop. Consequently, thermal insulation of the pipework is often specified in practice, with heating of hoppers or critical system components sometimes employed to prevent material solidification and ensure stable, reliable extraction operation.

ATEX requirements in facilities handling solid alternative fuels (SAF) are based on the risk of explosive fine dust generated during material handling, sorting, transport and storage. Consequently, the entire system is designed as a zoned installation with appropriate safety measures: the filtration unit must be ATEX-certified, featuring reinforced construction to withstand explosion pressure waves, explosion venting membranes for safe explosion relief, reinforced piping in critical sections between the filter and B-Flap valve, and certified rotary airlocks.

Sorbents are primarily employed in facilities handling solid alternative fuels (SAF) as an additional step to extraction or filtration. Sorbents, such as zeolite, are dosed into the airflow or specific sections of the technology to reduce moisture, capture odorous compounds, and partially stabilise dust particles. This is most commonly applied during the extraction from storage areas or enclosed spaces where SAF materials release moist and odour-laden air; the sorbent is either dosed directly into the ductwork or applied in a pre-stage section of the system before the filter. A properly designed sorbentation process helps mitigate condensation, reduces dust stickiness, and improves the overall stability of filtration plant operations.

Emission limits for facilities using solid alternative fuels (SAF) are governed by current legislation and the specific permit for the emission source. Typically, limits for total suspended particulates (TSP) are set around 10 mg/m³. However, in modern systems featuring high-quality filtration and properly engineered technology, it is standard practice to achieve significantly lower values, typically in the range of 1–2 mg/m³ TSP, which aligns with top-tier industrial solutions. Such low emissions are attainable primarily through the use of effective Flat HOUSE technical filters, correct regeneration processes, and stable performance control that maintains constant pressure conditions and high dust collection efficiency.

The most common errors in the design of TAP extraction systems stem from underestimating material characteristics and selecting inappropriate filtration technology for specific process stages. A typical example is using an unsuitable filter configuration, such as installing filters with top-entry between filter elements at a TAP sorting facility. This causes direct contact with heterogeneous materials, leading to blinding and clogging of the filtration area. Another frequent mistake involves inadequate sizing of transport velocities in ductwork, resulting in material deposition, or excessive speeds that increase wear and pressure losses. Other issues include underestimating bridging in hoppers, poorly designed filter regeneration systems, and a lack of coarse fraction pre-separation. Overall, TAP systems require specific design based on separation principles, robust filtration, and performance control; otherwise, frequent breakdowns and system blockages occur.

Air recirculation in facilities handling solid recovered fuel (SRF) is determined by the specific type of operation and its emission and safety requirements. In SRF sorting plants, it is often feasible and economically advantageous to fully recirculate a portion of the air, as filtration ensures adequate dust separation while simultaneously reducing heating and ventilation operating costs. Conversely, in SRF storage facilities, recirculation is typically restricted or entirely excluded, given the emphasis on moisture extraction, odour control, and environmental stability; therefore, full exhaust to the outside without returning air to the hall is preferred. Consequently, the correct configuration of recirculation always depends on balancing energy savings, air quality, and process safety.

The storage of solid alternative fuels (SAF) has a significant impact on air quality within the warehouse, as the material can release fine dust, moisture, and odorous compounds that accumulate rapidly in the space without proper extraction, thereby deteriorating the working environment. In practice, this means that without effective ventilation and ceiling-level extraction, there is an increase in dust, odour, and humidity, which can negatively affect both operator comfort and the technical condition of equipment within the hall. Therefore, SAF storage areas are typically managed through controlled ventilation and extraction systems designed to remove humid and contaminated air from the building.

Dust extraction at TAP loading and unloading points is typically addressed using extraction boxes or local hoods connected to a central dust extraction system. These points are equipped with control dampers, as the process is not continuous but intermittent, depending on current material handling operations. During loading or unloading, the damper opens to create local negative pressure directly at the source of dust generation, thereby minimising its escape into the surrounding environment. Proper sizing of these extraction points is crucial for system stability, ensuring that suction efficiency in other parts of the plant is not compromised.

Maintenance requirements for filtration equipment in facilities using solid alternative fuels (SAF) are higher than in standard applications. This is because the equipment handles heterogeneous, abrasive, and often sticky materials that place greater stress on filter media, regeneration processes, and dust extraction systems. In practice, regular visual and operational checks by operators are recommended, with particular attention to pressure drop, regeneration function, and material discharge. Additionally, professional servicing should be carried out at least twice a year to conduct detailed inspections of valves, filter elements, system sealing, ATEX components, and the overall functionality of the technology. Properly calibrated maintenance is essential to prevent bridging, blockages, and unplanned downtime, which are frequent risks in SAF operations.

The sizing of fans for TAP extraction systems is fundamentally governed by the same principles as other industrial applications: calculating the total pressure losses across the entire system, including ductwork, filtration units, dampers, and local resistances, while adding a performance margin—typically around 20%—to accommodate operational deviations and filter clogging. However, with TAP systems, it is additionally crucial to account for higher variability in system resistance over time, as the material tends to compact, bridge, and gradually increase pressure drop. Therefore, an adequate safety margin and high-quality control are essential for stable and long-term reliable operation.

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Grain storage extraction systems

The extraction of dust from grain handling conveyance systems is typically implemented as an integrated system tailored to specific transport technologies. It begins with the suction at the receiving hopper, where the highest levels of dust are generated during unloading and material handling; this stage usually requires a suction capacity of 15,000–20,000 m³/h. Bucket elevators and conveyors follow, designed as enclosed negative-pressure transport routes to prevent dust from escaping into the surrounding area. For belt conveyors, extraction is carried out using covers, typically with a capacity of around 1,200 m³/h per section, depending on length and dust intensity. Bucket elevators are generally sized at approximately 1,000 m³/h each, with the critical requirement being the maintenance of stable negative pressure throughout the entire path. In bucket elevators, extraction is addressed both at the boot and at the head, typically with a capacity of roughly 1,000 + 1,000 m³/h, as these two points are the most critical regarding dust leakage during filling and emptying. The entire system must be balanced to ensure uniform negative pressure, preventing the ingress of false air or any dust leaks at any point in the process.

The extraction of upper airways and the ventilation of silos are typically managed by a separate central filtration system, which ensures controlled ventilation during both the filling and emptying of individual silos. Key points in the technology connect to this system, particularly elevator heads, belt conveyor discharge points, and bucket elevators during the filling process into silos, where the largest volume of air mixed with dust is generated. Each silo is also equipped with its own ventilation system designed to remove air displaced by grain during filling, typically operating at a capacity of around 800 to 1,000 m³/h per silo. The entire system must be designed to remain balanced, maintain stable negative pressure, and prevent dust leakage into the surrounding environment during both filling and technology operation.

Grain silos are primarily used to store all major agricultural commodities, notably wheat, barley, and maize; however, in general terms, they accommodate any crop harvested from the field that requires cleaning, drying, and preparation for further processing or trade. From an extraction perspective, ATEX-compliant equipment is always essential due to the generation of explosive dust, although its characteristics vary significantly depending on the specific crop and harvest conditions. The proportion of fine particulate matter, residual soil, husk fragments, and organic impurities changes accordingly, influencing both dust levels and behaviour within the pipework and filtration system. Consequently, the entire system must be designed with adequate capacity reserves and tailored to accommodate variable material composition.

Dust from grain handling and cleaning lines is characterised by being dry, biological, and potentially explosive, with a variable composition depending on the crop type and cleaning quality. It contains fine dust particles, husks, soil residues, and organic impurities, often including light fibrous components, which influence its behaviour in airflow and within filtration systems. From a filtration perspective, it is generally less abrasive but tends to exhibit higher volumetric dustiness and fluctuating loading on the filter surface, typically ranging around 2 m³/m²/min depending on the technology. Due to its biological nature and fine particle fraction, ATEX compliance and properly designed filter regeneration are essential, as dust properties can vary significantly between wheat, barley, or maize.

The difference between local and central dust extraction in grain handling plants lies primarily in the scope and purpose of the system. Central extraction is employed when designing or upgrading an entire silo complex or technological unit, with the aim of removing dust from all major sources such as receiving hoppers, elevators, bucket conveyors, and transport routes. This prevents dust from escaping into the surrounding environment or re-entering the product. Older systems are often based on cyclones, which generally no longer meet current efficiency requirements or ATEX standards, and are therefore being replaced by modern central filtration solutions. Local extraction, on the other hand, is used where a central system already exists but specific points still exhibit excessive dust generation, such as a particular bucket conveyor or transfer point. In these cases, a local filter, for example a Local JET unit, is installed to address only that specific dust source. It returns the captured material back into the process flow, thereby complementing the central system and enhancing overall extraction efficiency.

The grain cleaner is a standalone technological unit, typically equipped with its own fan and requiring precisely defined extraction capacity that must be respected during the design of the suction system. If the extraction is undersized or incorrectly set, overpressure occurs within the cleaner, subsequently spreading to connected conveying lines such as elevators or bucket conveyors; if these remain inactive, this can cause undesirable dust accumulation and material build-up throughout the system. Therefore, proper design must ensure that the cleaner operates under slight negative pressure and that its own suction performance is not compromised by connection to a central system.

Requirements for filters handling grain dust are primarily determined by the nature of the material and the ATEX environment in which these systems operate. The foundation is an ATEX-compliant design for the entire filtration unit, as grain dust is fine, dry, and explosive. Filter media are selected with a smooth surface to minimise clogging and improve regeneration, while standard spacing between filter bags ensures uniform airflow and stable pressure drops.

Typical filtration velocity is around 2 m/min, which represents the optimal balance between efficiency and filter media lifespan. An essential component of the design is a sharp, well-supported hopper that minimises the risk of grain dust bridging, along with an ATEX-rated rotary airlock for safe material discharge. With proper engineering, these filters achieve very long service lives, often significantly exceeding 20,000 operating hours, since grain dust filters effectively at low pressure drop and does not cause excessive mechanical wear on the system.

The explosivity of dust in silos and cleaning lines is critical and must always be taken into account, as grain dust is a classic explosive dust within ATEX environments. For this reason, the entire system is designed to ATEX standards, typically Zone 20 in areas with persistent dust presence, along with adjacent Zones 21 and 22 in surrounding parts of the plant.

Filter units must be equipped with an anti-static design, earthing, and appropriate explosion propagation protection, such as explosion vents routed outside the building or a FLEX relief system. Safety devices of the B-Flap type are standardly used in pipework to prevent pressure waves from propagating back into the plant. An important component of the system is also a certified rotary feeder, which functions as a fire and explosion isolation valve between the filter and the discharge point. The entire system must be designed to minimise the risk of both initiation and propagation of an explosion throughout the whole plant.

The extraction of dust from loading points and grain conveyor routes is determined by the nature of operations and the intensity of dust generation at a specific location. For receiving hoppers—for instance, during unloading from trucks—surface extraction using side hoods positioned along the receiving hopper is employed. This approach addresses the very high yet discontinuous dust generation caused by rapid material pouring. Consequently, a higher extraction capacity is required, and the system typically includes dampers and control mechanisms to adjust performance according to the current load.

In contrast, conveyor routes such as bucket elevators or enclosed belt conveyors present a different scenario, as they represent a continuous and stable source of lower dust levels. Extraction systems are therefore designed for lower capacity, aiming to maintain a slight negative pressure within the route to prevent dust escape. The system is regulated via control dampers to ensure that the entire extraction circuit remains balanced.

Grain cleaners are typically extracted at capacities of approximately 6,000 to 10,000 m³/h, depending on their size and capacity. They are very often equipped with a dedicated filter that operates only when the cleaner is running, as this represents a specific and intense source of dust with variable load conditions.

For silos and their upper venting systems, flow rates typically range from 800 to 1,000 m³/h per silo. The primary function here is to remove the air displaced during filling and maintain a stable vacuum within the system. This extraction is usually connected to a central filtration system for the upper structure of the building, which ensures uniform ventilation across multiple silos simultaneously and stabilises the operation of the entire technology.

The extraction of filling and silo emptying is addressed as a comprehensive system integrated with the upper and lower structure technology. Silo filling takes place in the upper section, where material is distributed via elevators, chain conveyors, and belt conveyors into individual silos. These areas generate the highest volumes of displaced air and dust, which are extracted through the upper ventilation to a central filtration system. The lower section, responsible for silo emptying, operates under different conditions, focusing primarily on maintaining consistent extraction during material discharge from silos into subsequent transport stages. The upper and lower sections can operate simultaneously; for instance, when transferring material between silos. This places significant demands on the balance of the entire extraction system to ensure negative pressure is maintained throughout all parts of the technology, preventing dust leakage.

The moisture content of the grain itself does not significantly affect suction efficiency directly; however, it has a substantial indirect impact on overall plant operations. Higher moisture levels degrade the material’s storage properties and are undesirable primarily due to the risk of heating in silos or subsequent mould growth. Therefore, it is essential to monitor moisture levels and maintain them within specified limits to prevent degradation of the stored grain quality. From a suction perspective, what matters most is ensuring that moist air is properly extracted and that condensation does not form within the system, which could lead to dust accumulation and operational issues—a scenario that is uncommon in practice.

In grain processing plants where we exclusively use textile filter bags in Jet BAG and Flat HOUSE systems, the service life of the filter elements is very high, typically significantly exceeding 20,000 operating hours. With a correctly designed regeneration system and stable operating conditions, these filters are completely reliable and ensure long-term consistent filtration efficiency without the need for frequent replacements.

Filter regeneration in grain silos is most commonly achieved using the JET system, which employs short pulses of compressed air to periodically shake the filter bags and dislodge captured dust. The dust then falls into the filter hopper and is subsequently conveyed via a rotary feeder into downstream exhaust or process ducts. As most silos lack their own compressed air supply, the filtration system delivery typically includes either a compressor or a centralised air distribution network to ensure reliable regeneration performance. A correctly designed JET system is essential for maintaining stable pressure drops and extending the service life of the filter elements.

Cartridge filters are not used for grain dust because the pleats would quickly become clogged with husks, bran and fine fibrous particles, which are very difficult to regenerate within them. Flat textile bag filters (bags) in an antistatic version are the standard; these feature an open filtration area, regenerate well and maintain stable pressure drops over the long term. In practice, this is the most reliable solution for grain processing plants, offering a very long service life and minimal operational issues.

Preventing dust accumulation in grain system pipelines is critical, as this is explosive (ATEX) dust; any buildup increases both risk and operational instability. The fundamental rule is to maintain a transport velocity of approximately 20 m/s, ensuring that the dust remains suspended in the airflow and does not settle within the pipework. Correctly designed flow velocities, combined with smooth pipeline routes, effectively ensure that the system remains clean and free from deposits even during long-term operation.

The most common errors in silo extraction design are poorly sized duct runs, which lead to uneven power distribution within the system, and incorrectly determined extraction capacities at individual suction points. Another frequent issue is under-sizing the extraction for grain cleaners or completely overlooking the extraction of receiving hoppers, where dust generation is highest. A further critical mistake is using an unsuitable filtration type, such as cartridge filters instead of fabric bag filters, which are more suitable for grain dust in terms of regeneration and service life. Poorly designed discharge points with a shallow slope or blunt shape also cause material bridging and disrupt dust extraction. Overall, these errors result in unstable operation, increased dust levels, and reduced efficiency of the entire system.

Air recirculation in grain cleaning plants is not typically addressed directly within the cleaner technology itself, but rather through an associated filtration system. The cleaner usually draws air from its immediate surroundings and discharges the dusty airstream into a filter. The filtration unit then enables recirculation: once the air has been cleaned, part or all of the filtered volume can be returned to the silo area or process equipment. This creates a closed-loop circulation system that eliminates the need for exhaust to the outdoors—a common solution in modern grain facilities from both an energy efficiency and dust control perspective.

ATEX requirements for grain handling and storage are based on the presence of explosive organic dust, meaning the entire system must be designed in accordance with ATEX zones and explosion protection measures. The foundation lies in correctly sized extraction, where a transport velocity of approximately 20 m/s is maintained within the ductwork to prevent dust accumulation.

Safety elements such as B-Flap valves are installed along the route between the machinery and the filter to prevent the back-propagation of pressure waves into the equipment and piping; these sections must therefore be pressure-resistant. The filtration unit must be anti-static and equipped with explosion relief devices, such as membranes or a FLEX system, to ensure controlled venting of pressure waves outside the hazardous area. A certified rotary airlock also forms part of this safety chain, acting as both an airtight seal and a safety barrier between the filter and the discharge point. The entire system must be designed to prevent both the initiation and propagation of explosions throughout all equipment.

Vacuuming during the loading and dispatch of grain is typically addressed at lower conveyor lines that transport the grain to the filling point for loading into trucks or railway wagons. The actual filling process most commonly employs a telescopic filling spout, which is extracted with a capacity of approximately 1,500 m³/h to minimise dust emissions during filling and maintain a clean working environment.

The entire system must be designed to handle both the continuous transport of material along the lower conveyors and the short-term but intense dusty peaks that occur during filling, when the greatest release of fine grain dust takes place.

The influence of grain dust fineness on filter design is not critical in the sense that it must always be treated as a variable parameter beyond control throughout the year. Dust characteristics vary according to humidity, harvest temperature, crop type and current harvesting conditions; therefore, filter designs are always made with an operational margin.

For this reason, a specific loading of approximately 2 m³/m²/min on the filtration area has proven effective in practice across various grain processing facilities, ensuring stable operation even when dust fineness fluctuates during the year.

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Extraction of gas and electric furnaces

Exhaust extraction from aluminium gas furnaces is handled by a high-temperature-resistant extraction system connected directly to the emission source. The exhaust gases are conveyed through central thick-walled piping designed for high temperatures and operational stress. The entire system is typically constructed in stainless steel or using heat-resistant materials such as Meta-aramid to ensure long-term stability under demanding operating conditions. The design also incorporates thermal insulation for both the pipework and the filtration unit, minimising heat loss and the risk of condensation. Filtration is most commonly addressed using Jet BAG or Flat HOUSE units adapted for high-temperature applications, often featuring controlled sorbent dosing to reduce emissions and capture fine particulates. An important component is also the heating of discharge hoppers, which prevents condensation and dust caking at the material outlet point. The extracted air is subsequently conveyed via a fan and discharged into the external environment through a chimney. The entire system must be designed to withstand temperature spikes, variable loads, and continuous furnace operation.

Extracting flue gases from electric metal furnaces is structurally simpler than for gas-fired units, as the exhaust gases are at lower temperatures, typically around 60 °C, and contain less moisture or reactive components that could cause condensation or chemical loading on the system. The extraction system comprises a standard ductwork network, a filtration unit, and a fan; thermal insulation of the ducts and filter is not required. Key considerations include correctly sizing the extraction capacity according to the furnace gas volume and ensuring stable fan operation to maintain consistent exhaust flow and negative pressure within the process. Filtration selection depends on the nature of dust from metal melting, with the overall system generally requiring less heat resistance while still meeting efficiency and operational safety standards. The recommended filter is the Jet BAG.

The difference between gas-fired and electric furnaces from a filtration perspective lies primarily in the nature of the exhaust gases and their chemical and thermal load. A gas furnace typically produces moister exhaust at higher temperatures, requiring management of chemical components such as HF or HCl; this places greater demands on the material specification of both ductwork and filtration units. Conversely, an electric furnace usually generates drier exhaust with lower temperatures around 50–60 °C and without significant chemical load, thereby eliminating the need to address moisture or condensation issues. For this reason, filtration in electric furnaces is structurally simpler, whereas gas-fired furnaces require more robust and chemically resistant solutions for the entire extraction and filtration technology.

The primary sources of pollution in melting furnaces are the flue gases and melt products themselves, which arise both during continuous tapping while melting and during furnace handling. Opening the furnace doors or venting flues during material handling also constitutes a significant emission source, as it causes sudden releases of contaminated air into the workspace.

These situations must be addressed through local extraction systems, most commonly using covers or hoods above the furnace (so-called “canopies”), which capture escaping flue gases directly at the source and prevent their spread throughout the hall.

Exhaust gases from aluminium melting furnaces contain a combination of solid, gaseous and chemical components generated both during the metal melting process itself and when processing impurities and contaminants in the charge. Typically, these consist of fine dust particles and metallic aerosols, as well as organic compounds (VOCs) released from contaminated materials, and acidic components such as HCl and HF, which are produced particularly when processing dirty or alloyed material. In addition, exhaust gases may contain metal oxides, fine particulate matter and other by-products of the melting process. For this reason, filtration and extraction systems for aluminium furnaces must be designed to handle both dust loading and the chemical aggressiveness of the exhaust gases, as well as operational temperature fluctuations.

Flue gas filtration for various metals does not differ significantly based on the metal itself, but rather according to the type of furnace and melting process. The main distinction lies between electric and gas-fired furnaces, as they generate different temperatures, moisture levels, and chemical compositions in the flue gases. In electric furnaces, the exhaust is generally drier and more stable, whereas gas-fired furnaces produce higher temperatures, greater humidity, and often contain acidic components such as HCl or HF, depending on the charge material. The molten metal itself mainly influences the quantity and nature of dust particles (e.g., metal oxides), but the fundamental principles of filtration and technology design remain very similar – the key factors are always temperature management, chemical load, and dust levels, rather than the specific type of metal.

The design of the extraction system for melting furnaces is always based on the manufacturer’s technical requirements, particularly regarding the flow rate of exhaust gases, temperature, and the required negative pressure at the connection point. The design typically accounts for multiple furnace operating states, such as melting, heat maintenance, and tapping (casting), with each state potentially involving different gas volumes and pressure conditions. For system sizing, the worst-case operating scenario is always considered—specifically, the combination of maximum flow rate and thermal load—while other modes are managed through fan speed control and damper regulation. This ensures that the system operates stably across all furnace running modes without risk of negative pressure fluctuations or insufficient extraction.

Sizing the extraction capacity for aluminium furnaces is carried out in the same way as for other metal furnaces – we always base our calculations primarily on the furnace manufacturer’s data, namely the required flue gas flow rate, temperature and necessary negative pressure at the extraction point. If these figures are not available, the extraction performance is determined by calculation based on the thermal output of the furnace and the anticipated production of flue gases, or alternatively according to empirical values from similar applications. The worst operating conditions are always taken into account so that the system can handle peak loads during melting, while lower modes are subsequently managed through regulation of the fan speed and dampers.

The number of furnaces has a direct impact on the design of the filtration unit, as the total extraction capacity required increases with the number of emission sources. However, it is not merely a matter of simply adding up the capacities; rather, the key lies in addressing the simultaneous operation of individual furnaces and their various operating states (melting, holding, tapping). Therefore, the design always accounts for realistic concurrent scenarios, rather than assuming all furnaces operate at maximum capacity simultaneously. Equally important is the correct balancing of the system using control dampers at each furnace, which allow individual branches to be regulated according to the vacuum level within the system. This ensures stable extraction even during variable operations and prevents overloading the filtration unit or, conversely, insufficient extraction from specific sources.

Centralised extraction for multiple furnaces connected to a single filter is implemented as a controlled negative pressure system, where individual furnaces are linked via extraction ducting equipped with automatic control dampers. Each furnace features independent flow control based on its current operational status, allowing for the balancing of varying exhaust gas volumes during melting, holding, or tapping phases. The common collection pipework connects to a filtration unit, where stable negative pressure is maintained by a fan driven by a variable frequency drive that responds to the system’s total demand. Cleaned exhaust gases are then discharged into the atmosphere via a chimney. Proper system balancing is critical to prevent interference between individual furnaces and to ensure consistent extraction from all sources at all times.

In practice, the distribution of performance across multiple furnaces is managed using automatically controlled regulating dampers on individual branch lines. Each furnace has its own damper, which positions itself according to the current demand, thereby throttling or opening up the flow of extracted flue gases accordingly. Control is always linked to vacuum measurement taken directly at the furnace, ensuring that the system responds to real operating conditions rather than relying solely on fixed set values. Ideally, this control should be integrated with the furnace’s own control system, which determines the required extraction level for each specific mode of operation. The central fan of the filtration unit then maintains the overall vacuum within the system and compensates for changes as individual dampers open or close. This ensures stable and balanced operation of the entire extraction system, even when multiple furnaces are running simultaneously under varying conditions.

The design of the ductwork system for melting furnaces is always addressed as a combination of the most critical operating conditions, namely short-term peaks and long-term stable smelting regimes. The sizing must accommodate the highest power output, which typically occurs when furnace doors are opened or during sudden flue gas leaks, while simultaneously ensuring that the system operates stably over the long term in the actual melting regime, which constitutes the primary operational load.

Consequently, ducts are designed to handle high volumetric flow rates without significant pressure losses and to prevent dust deposition during normal operation. This requires correctly selected pipe diameters, adequate transport velocities, and smooth routes free from critical points where blockages might occur. The entire system must also be balanced with regulation at individual branches, enabling stable control of extraction from multiple furnace states and adaptation to current operating conditions. Typical flow velocities are around 13–14 m/s during smelting and 23–25 m/s when extracting the hood.

Underpressure in systems with multiple sources is managed through intelligent regulation, where each furnace has its own control damper equipped with a sensor and linked to the furnace’s control system. The dampers operate independently, drawing the required extraction capacity based on the current operational status of each source. This results in varying pressure conditions across individual branch lines, while a constant underpressure is maintained in the main collector duct via a fan driven by a variable frequency drive. Consequently, the system automatically balances itself according to the number of active furnaces and their operating modes, preventing airflow competition between branches or fluctuations in extraction performance.

Extraction control for multiple furnaces connected to a single filter is managed via individually controlled dampers on each branch, operating according to the current operational mode of each furnace. This ensures that each furnace draws only the airflow capacity it requires at any given moment, with the system automatically adapting to operational changes. The entire extraction system is subsequently stabilised by a central fan equipped with a variable frequency drive, which maintains constant negative pressure on the filtration unit regardless of the number of active sources.

Damper control for multiple exhaust sources is achieved using servomotors with continuous positioning, enabling precise adjustment of extraction capacity for each source. The dampers are controlled either by a 4–20 mA analogue signal from the control system or via a communication bus (e.g., an industrial network), where the furnace controller or central PLC sets the required position according to the current operating status.

This approach allows dynamic balancing of individual extraction branches, maintaining stable negative pressure within the system while responding to changes in the operating modes of individual furnaces without manual intervention.

System balancing at varying furnace outputs is managed to maintain a stable vacuum in the central filter duct, corresponding to the requirements of the most distant or hydraulically demanding furnace. Each branch is equipped with control dampers that adjust the airflow by adding or restricting it according to the current operating status of each furnace, allowing the entire system to dynamically adapt to output changes. The central fan then merely compensates for the overall system vacuum, while distribution among individual furnaces is controlled locally. This ensures stable functional extraction across all branches without system collapse, even during uneven operation of all furnaces.

The alternating operation of the furnaces is managed as a simple and fully adaptable mode in which only one furnace operates at any given time, while the other is either offline or in standby. The entire extraction system is designed accordingly – both the ductwork and the filtration unit are sized to handle the full capacity of the active furnace, yet they also allow for partial load operation without compromising system stability.

Control is achieved through closing and regulating dampers on individual branches that automatically isolate the inactive furnace while fully opening the branch connected to the active one. The filter and fan then operate at their optimal working point for the current state, enabling the system to adjust between full and partial capacity without requiring any physical changes to the technology.

The current operation of multiple furnaces is managed by ensuring that the entire extraction system is always sized for the maximum simultaneous output of all furnaces in their most critical operating states. This means that calculations consider not just a single source, but a defined combination of individual furnaces and their modes (melting, holding, tapping). Each furnace is connected via an independent control branch with a damper, allowing its share of the total capacity to be adjusted according to current conditions. The central fan and filtration unit are then designed to handle the sum of these outputs with sufficient reserve, maintaining stable negative pressure in the system even during full simultaneous operation. This ensures safe and stable operation without fluctuations in extraction between individual sources.

Regulation has a fundamental impact on the fan’s energy consumption and significantly reduces it in practice. By means of frequency converter control and regulating dampers, the fan does not operate continuously at full capacity but adapts to the current extraction requirements based on the number of active furnaces and their operating states.

Consequently, the fan runs most of the time at a lower operating point where energy consumption decreases with the cube of the rotational speed; therefore, even a small reduction in output results in substantial electrical energy savings. Properly designed regulation not only stabilises the vacuum within the system but also substantially optimises the operational costs of the entire extraction process.

The solution for high flue gas temperatures from furnaces is always designed according to the specific application and the required temperature resistance of the entire system. Essentially, three main approaches are used. The first involves controlled intake of ambient air, which cools the flue gases to the required inlet temperature for the filter. The second option is the use of a dedicated flue gas cooler, ensuring controlled temperature reduction without affecting the process through dilution.

The third alternative is the deployment of high-temperature filtration systems, such as Ceramic JET or Steel JET, which are specifically engineered for operation with hot flue gases without requiring significant cooling. The choice of a specific solution always depends on the temperature, chemical composition of the flue gases, and the overall technology concept.

With conventional fabric filters, flue gas cooling is usually necessary because the filter media have a maximum operating temperature. Therefore, a safety (emergency) intake damper is always installed to allow immediate cooling of the flue gases to a safe inlet temperature for the filter in the event of system overheating, thereby preventing damage.

Conversely, with high-temperature systems such as Ceramic JET or Steel JET, flue gas cooling is generally not required because these filters are designed specifically for operation at high temperatures without the need for dilution or air intake.

Flue gas cooling in industrial extraction systems is typically addressed through three primary methods: dilution, coolers, and heat exchangers. Each method serves a distinct purpose depending on the temperature, nature of the flue gases, and overall technological design.

Dilution (intake of ambient air)

The simplest cooling approach involves controlled intake of ambient air into hot flue gases. This reduces their final temperature to a level manageable by the filtration equipment. It is primarily used where rapid and straightforward regulation is required without additional technological components. The system typically includes an emergency damper designed to protect the filter during temperature spikes or control failures.

Flue gas coolers

Coolers represent standalone technological equipment that actively reduces flue gas temperatures in a controlled manner. These may be air-cooled or combined units, enabling precise temperature regulation without significantly affecting volumetric flow rates. This solution offers greater stability than simple dilution and is employed where maintaining consistent inlet conditions for the filter over the long term is essential.

Heat exchangers

Heat exchangers allow controlled cooling of flue gases with the option to recover heat. Thermal energy from the flue gases is transferred to another medium (such as air or water), which can then be utilised within operations. This solution is the most efficient in terms of energy recovery, yet it is also the most complex and capital-intensive to construct. It is mainly deployed where heat recuperation makes economic sense.

The maximum temperature for entering the filtration units always depends on the type of technology and filter media used. With conventional fabric (textile) filters, temperatures typically reach up to approximately 200 °C; this limit is determined by the material of the filter bags and the filter construction. Above this temperature, it becomes necessary to implement cooling or flue gas dilution. High-temperature systems such as Ceramic JET or Steel JET can operate at temperatures of around 400 °C, and in certain specialised applications even higher, depending on the specific configuration and technology employed. These systems are designed specifically for environments where conventional filtration would no longer be viable.

Thermal shocks within the system are addressed through the design of the filtration unit and the overall technology, ensuring that individual components are prepared for these changes. The filter must be dimensioned structurally and materially to withstand rapid temperature fluctuations without deforming or damaging the filter media.

An important aspect is the thermal insulation of both the pipework and the filtration unit itself, which helps stabilise the temperature profile and minimises rapid local cooling or overheating. The discharge point is also a critical area; it is typically heated to prevent condensation and subsequent dust caking or bridging during temperature changes.

The entire system is therefore designed so that thermal fluctuations are absorbed structurally, rather than requiring additional operational interventions.

The influence of temperature on the lifespan of filter media is fundamental and constitutes one of the key factors in the design of the entire system. Each filter material has a precisely defined maximum operating temperature that must be adhered to over the long term. If this limit is exceeded, rapid degradation of the filter media occurs – resulting in loss of mechanical strength, deterioration of filtration properties, and a significant reduction in service life. In extreme cases, damage or burning through of the filter fabric may occur. Therefore, it is always essential to design the system so that the temperature at the filter inlet remains consistently within the permitted range, including measures to address peaks arising from operational changes in the process.

For aluminium furnaces, high-temperature bag filters of the Jet BAG type are most commonly used. These are designed for demanding flue gas applications involving variable temperatures and higher chemical loads. The filtration unit is typically constructed from stainless steel, including the discharge hopper, to ensure corrosion resistance and long service life in operation. The design also includes thermal insulation for the filter and often a heated discharge hopper, which prevents condensation and dust caking at the material outlet point. High-temperature materials are used as the filtration medium, most commonly meta-aramid, capable of withstanding elevated temperatures and operational temperature cycles. The filter construction is engineered to handle frequent chamber cycling, ensuring stable operation even under variable loads across different furnaces and their operating modes.

For flue gas applications, only baghouse (fabric) filters are used because they are structurally suitable for high temperatures, variable loads, and demanding operations such as melting and foundry furnaces. Cartridge filters are not employed in these applications; they are unsuitable for thermal cycles, high volumetric flow rates, or typical flue gas loading, and are not standardly specified in practice for such processes. Baghouse filters, on the other hand, allow the use of high-temperature materials (e.g., meta-aramid), can handle cyclic chamber operation, and remain stable over time even under fluctuating furnace conditions.

For high-temperature filtration applications, several types of materials are used depending on the temperature, chemical load, and operating conditions. The foundation is Meta-aramid, which is employed for standard high-temperature operations and handles common industrial flue gas applications well.

For higher chemical resistance and finer filtration requirements, PTFE (Teflon) is used, offering excellent chemical stability and low dust adhesion.

For extremely high temperatures, ceramic filter media are deployed, capable of withstanding temperatures significantly above the limits of conventional textile materials.

A special category comprises non-woven microporous metal fabrics, which are used in the most demanding applications where a combination of high temperature, abrasiveness, and long-term mechanical stress is present.

In foundry operations, the service life of filter elements is typically designed for approximately 20,000 operating hours or more, depending on the specific application and operational conditions. With a correctly engineered system—characterised by appropriate filtration velocity, effective regeneration, and stable thermal regimes—it is common to achieve this lifespan even in demanding exhaust gas applications. It is crucial to maintain the filter at its optimal operating point and prevent overloading of the filtering area or temperature spikes that significantly reduce media life.

Filter regeneration in flue gas systems is addressed through a combination of several proven principles, depending on the type of filtration unit and operating conditions.

The foundation lies in the JET system, which involves flushing filter elements with short pulses of compressed air. This process dislodges captured dust from the filtering surface and maintains stable pressure drop within the system.

Additionally, chamber cycling is employed, whereby individual filter sections are alternately taken offline for regeneration in so-called offline mode. This enhances cleaning efficiency, particularly in heavily loaded flue gas applications.

In certain cases, offline regeneration is also combined, wherein a portion of the filter is completely removed from operation and regenerated under static conditions. This approach is suitable for demanding environments with high dust loads or sticky particulates.

Properly designed regeneration is crucial for stable operation, low pressure drop, and extended service life of the filtering media.

In the filtration of exhaust gases from metal melting furnaces (e.g., aluminium), ATEX compliance is not typically a standard fundamental requirement for the entire system, as an explosive dust atmosphere at concentrations defining ATEX zones within the filter is generally absent. The primary concerns are oxide and metallic dusts and fumes, where temperature resistance, chemical durability (e.g., against HF or HCl in gas-fired furnaces), operational stability, and proper filter regeneration are paramount. Consequently, ATEX considerations are addressed only marginally and locally in specific instances, such as with particular fine metal powders or associated handling and discharge sections of the plant.

Spark suppression in exhaust systems is designed as a combination of several protection levels, depending on the length of the pipework and the nature of the operation. In long pipeline runs, sparks usually extinguish naturally due to cooling and energy loss by particles; this constitutes the first passive level of protection. To enhance safety, a spark separator is typically installed in the suction duct, which actively separates or quenches sparks before they enter the filtration unit. Another layer of protection involves sorption or controlled conditions within the filter, helping to eliminate residual hot particles and safeguarding the filter medium from damage or ignition. The entire system is always designed as multi-stage to ensure operational safety even under varying conditions.

For foundries, particularly for hot flue gases from melting furnaces, robust filtration units designed to withstand high thermal and chemical stress are employed. These typically feature stainless steel cabinets and hoppers, ensuring corrosion resistance and long-term stability in aggressive environments. The entire filter is usually thermally insulated and equipped with heating elements in critical sections, especially the hopper, to prevent condensation and subsequent corrosion or dust caking. A key requirement is high durability and resistance to acidic components of flue gases generated during melting processes; therefore, materials and construction are selected so that the system can reliably handle thermal cycles and chemical loads over time without functional degradation.

Yes – in the case of flue gas and hot processes, this is practically an absolute necessity.

Filters must be thermally insulated because, without insulation, the filter walls cool down, leading to the condensation of aggressive components in the flue gases. This subsequently causes acid formation, structural corrosion, dust agglomeration, and a gradual deterioration of the filtration unit’s performance. Therefore, insulation is not merely an “energy-saving measure” but primarily operational protection for the technology and a crucial factor in extending the lifespan of the entire system.

The expansion of pipework at high temperatures is managed using compensators, which allow the piping system to accommodate thermal movement without generating excessive stress within the structure. When heated, pipes undergo significant elongation; if the system is not designed with sufficient flexibility, these thermal expansions are transferred to welds and load-bearing structures, leading to cracking or deformation. Therefore, pipework routes must always incorporate expansion joints to compensate for these movements, ensuring long-term reliable and safe operation even at high flue gas temperatures.

Discharge requirements for flue gas filters are critical to the proper functioning of the entire system, as this area is subject to high thermal and operational stress. The discharge hopper is typically made of stainless steel, thermally insulated, and often heated to prevent flue gas condensation, which could otherwise lead to dust caking or corrosion. The design usually includes an inspection and service opening for regular maintenance and visual assessment of the condition. Most commonly, the hopper is sealed with a rotary feeder, ensuring smooth and leak-free material discharge while preventing the ingress of false air into the filtration unit.

Dust extraction from the filter is most commonly addressed using two fundamental methods, depending on the overall technology concept. The first option involves local extraction via a rotary airlock valve, where dust is continuously and tightly metered into big bags, containers, or other downstream equipment. The second option is central collection, where material from multiple filters or chambers is conveyed to a single common location using a chain conveyor. Screw conveyors are generally not recommended for these applications, as they tend to exhibit higher mechanical wear and noise levels during long-term operation, which has proven unsuitable in practice for flue gas and industrial filters.

To extract hot dust, special rotary feeders with metal sealing strips are used. These are engineered for high temperatures and abrasive environments. Typically, they feature a heavy-duty design, such as the RPGG-HL series, which is specifically intended for flue gas and foundry applications.

These feeders boast a robust construction, heat-resistant bearings, and metal scraping/sealing elements instead of rubber, enabling them to withstand long-term operation without degradation at elevated temperatures. In practice, they ensure reliable and leak-free extraction of hot dust from the filter hopper, even under demanding operating conditions.

The filtration of aluminium and steel does not differ significantly in principle; in both cases, it involves the extraction and filtration of fumes from melting furnaces. The decisive factor is less the metal itself and more the type of furnace, specifically whether it is electric or gas-fired.

The main difference lies in the composition of the fumes. In gas-fired furnaces, there is a higher moisture content, and the presence of gaseous components such as HF or HCl must often be addressed depending on the charge characteristics. Conversely, fumes from electric furnaces are drier and chemically simpler. Therefore, from a filtration perspective, the distinction is not so much between aluminium and steel, but rather between operational technology and the chemical load of the fumes.

The specific characteristics of aluminium dust from an ATEX perspective depend fundamentally on the type of dust involved. Fumes and ash from aluminium melting furnaces typically do not pose a significant ATEX risk, as they consist mainly of oxidic, already “burnt” particles with low reactivity.

Conversely, fine metallic aluminium dust, such as that generated by grinding, machining or dry material separation, is highly reactive and can be strongly explosive in its fine fraction. It is precisely this type of dust that creates a genuine ATEX risk, particularly when dispersed into the air and in combination with an ignition source.

From a technology design standpoint, it is therefore essential to distinguish between inert oxidic residues from melting processes and active metallic dust resulting from mechanical processing, as their behaviour within the system differs completely.

Dust from alloyed metals presents specific challenges, primarily in that its behaviour within extraction and filtration systems varies significantly depending on the precise composition of the alloy. Compared to pure metals, it contains higher levels of impurities which alter its thermal stability, chemical reactivity, and abrasiveness. In practice, this results in greater variability in properties: some dust components may be inert oxides, while fine metallic fractions can remain reactive or even pose an ATEX hazard.

Another key characteristic is the increased abrasiveness of certain alloys (e.g., Mn, Cr, Si), which places greater stress on pipework, cyclones, and filter media. In gaseous processes, aggressive combustion by-products may also be present, further increasing the demands for chemical resistance in filtration.

From a system design perspective, it is therefore essential when handling alloyed metal dust to account for higher uncertainty in material behaviour, incorporate greater margins in sizing calculations, and rigorously address both temperature control and potential chemical reactions throughout the entire extraction chain.

Metal oxidation has a fundamental impact on the filtration system as it significantly alters the chemical and corrosive conditions throughout the entire plant. In specific applications such as syngas or environments with higher concentrations of active metal vapours and fine oxides, substantial chemical degradation of materials can occur, including pitting corrosion in pipework, filter housings, and associated components. In these cases, it is necessary to address not only filtration itself but also the stabilisation of the gaseous environment—for instance, through controlled flushing with inert gas to limit oxygen access and thereby reduce oxidation rates. Appropriate material specifications are simultaneously selected (stainless steel, higher-grade steels, or special surface treatments) to ensure the system withstands chemical stress over the long term. Overall, oxidation affects not only filter lifespan but also the reliability of the entire extraction chain; therefore, it is always considered during the technology design phase.

Fine metallic dust, such as that generated during grinding or machining operations, is treated as a highly sensitive application in terms of both ATEX compliance and spark and high-abrasion risks. The foundation lies in a conventional extraction system sized to ensure sufficient transport velocity, thereby preventing dust accumulation within the ductwork. The system includes a spark separator designed to protect the filtration unit from any hot particles originating from the grinding process. Subsequently, the dust is captured by a filter, typically of the Jet BAG type with an antistatic filtering medium capable of safely handling fine and potentially explosive fractions. The entire system must be engineered as an ATEX-compliant solution, incorporating earthing, antistatic components, and properly designed dust discharge mechanisms. This is essential because fine metallic dust possesses high energy potential and can form explosive mixtures when combined with air.

Energy consumption in flue gas filters can be reduced primarily through correct system regulation and filter design featuring sufficient filtration area, ensuring operation at the lowest possible pressure drop. It is essential that the fan does not run unnecessarily under overpressure but operates at its optimal working point according to current extraction requirements.

Correctly designed damper control and frequency-regulated fans also have a significant impact, allowing performance to be matched to actual furnace operation and thereby minimising unnecessary energy losses. In practice, a well-designed filtration area and stable low pressure drop are fundamental prerequisites for the long-term energy-efficient operation of the entire system.

Fan speed control has a fundamental impact on energy consumption, as it allows the extraction performance to be adjusted to the system’s current requirements rather than running continuously at maximum capacity. When using a variable frequency drive (VFD), the fan speed is varied; notably, energy consumption decreases much more rapidly than the power output itself – even a small reduction in rotational speed results in significant electrical energy savings.

Combined with damper control for individual sources (e.g., furnaces), this ensures that the fan operates most of the time at its optimal point, rather than under overload or unnecessarily high performance. A properly designed control system therefore substantially reduces the operating costs of the entire flue gas system while simultaneously stabilising suction pressure.

In practice, heat recovery options for fume extraction primarily focus on how effectively the residual heat in exhaust gases can be utilised before they are discharged into the chimney. The most common solutions involve gas-to-air or gas-to-water heat exchangers, which facilitate heat transfer to another medium for further operational use, such as hall heating or process water preheating.

However, precise temperature control upstream of the exchanger is crucial. In conventional systems, exhaust gases are typically cooled to approximately 120 °C; below this threshold, condensation of aggressive components may occur, leading to corrosion.

In more advanced systems, heat recovery is implemented after high-temperature filtration stages, such as Steel JET or Ceramic JET. These units first withstand the extreme temperatures of the exhaust gases before a heat exchanger is installed downstream in the ‘cleaned’ gas stream. This approach protects the heat recovery technology itself while maximising thermal efficiency without risking fouling or chemical degradation.

The extraction efficiency of furnaces is improved by combining proper design, control, and optimised capture of flue gases directly at the source. The foundation lies in a correctly designed furnace hood that captures escaping fumes as effectively as possible before they disperse into the surrounding area.

Furthermore, regulating extraction power according to the furnace’s current operating state is crucial, ensuring the system does not unnecessarily run at full capacity while always maintaining stable negative pressure during critical phases (melting, tapping, and door opening).

Equally important are sufficient overall fan capacity and correct balancing of the ductwork system to prevent interference between individual extraction points and loss of efficiency. In practice, peak performance is achieved through a combination of high-quality hoods, precise control systems, and appropriately sized extraction capacity.

Filter maintenance in foundry furnaces is managed through a combination of scheduled shutdowns and operational maintenance within individual filter chambers. In practice, routine servicing tasks such as valve inspections, regeneration, leak testing, or replacement of worn components are often carried out while part of the filter system remains offline. This allows specific chambers to be isolated using dampers, enabling the remainder of the system to continue operating. Thanks to this chambered design, it is unnecessary to shut down the entire filter; maintenance can instead be performed incrementally on individual sections, thereby minimising production downtime. More extensive interventions, such as replacing filter elements or conducting a full system overhaul, are typically scheduled during planned technological shutdowns. The overall objective is to maintain continuous filter operation while ensuring long-term reliability and consistent performance.

Filter elements in foundry and flue gas applications are typically replaced after approximately 20,000 operating hours, which is a standard design interval for a properly engineered system. However, service life can be extended if regulation is well managed, the temperature regime remains stable, regeneration is performed correctly, and there is no overloading of the filter area or frequent temperature spikes or chemical stress. Conversely, in poorly designed or overloaded systems, replacement may be required sooner. Therefore, it is not merely the operating hours that matter, but the actual conditions under which the filter operates.

The most common exhaust system faults are primarily linked to incorrect or sluggish control, where the system fails to respond promptly to changes in furnace operating conditions, leading to vacuum fluctuations. Another frequent issue is poorly sized suction ducting, which results either in excessive pressure losses or, conversely, dust accumulation within the pipes. Damage to the filter media is also a significant source of faults, potentially caused by overload, thermal shock, or chemical loading from the exhaust gases. Overall, most problems can be traced back to an incorrect system design or inadequate control of operating conditions.

Pipework fouling in hot flue gas applications is primarily addressed through correct route design and operational measures, as preventing dust deposition and condensation is critical. The foundation lies in inspection and cleaning openings at key points in the pipework, allowing for regular checks and mechanical removal of deposits.

Operationally, pipe flushing using maximum fan output is often employed; this temporarily switches the system to a high-flow regime, helping to carry deposited material back into the filtration unit. However, correct sizing of flow velocity and elimination of dead zones in the pipework during the design phase are equally important, as prevention is essential in these temperature-critical applications.

Fan servicing for high-temperature flue gas systems is always carried out after the unit has been shut down and cooled safely to ensure conditions are met for safe handling. In the first phase, the fan is completely isolated, secured against accidental start-up, and its temperature condition is checked.

Subsequent servicing follows essentially the same procedure as for a standard fan – checking bearings, impeller balancing, blade condition, sealing integrity, and vibration levels. However, in high-temperature applications it is additionally crucial to monitor thermal stress, potential deformations, and the condition of bearing mounts, since operation at elevated temperatures increases component wear.

Overall, therefore, while the basic servicing procedure remains the same, higher temperatures necessitate more rigorous inspection of both mechanical and thermal stresses.

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CNC Laser Extraction

CNC laser extraction is addressed by connecting directly to the machine flange, where the extraction capacity is selected based on the size and power of the laser: approximately 5,000 m³/h for standard laser workstations and up to around 8,500 m³/h for larger or high-performance lasers. The extracted air is routed through spiral ducting to a central or local filtration unit, always incorporating an integrated spark separator to protect the filter from hot particles generated during the cutting process. Subsequently, the air is cleaned in a Jet BAG-type unit and, depending on operational requirements, may be recirculated back into the hall in summer/winter mode or exhausted outdoors. The entire system is designed to ensure stable extraction, technology protection, and energy-efficient operation.

Suction performance for CNC lasers is sized according to the work area dimensions and machine type. For standard lasers with a 1500 × 3000 mm format, suction rates of around 5,000 m³/h are typically used; tubular lasers require approximately 1,500 m³/h, while large laser centres with a 2000 × 5000 mm work area operate at around 8,500 m³/h. These values ensure consistent extraction of fumes and fine metal dust during cutting.

Laser cutting extraction is always sized according to the specific requirements of the machine and its operating mode, namely the recommended airflow and vacuum level at the connection point. Crucially, however, the filtration system must be able to maintain constant suction even as the filter surface becomes progressively clogged. In practice, Jet BAG tube systems have proven highly effective, maintaining stable pressure drops and a service life of around 20,000 operating hours. Conversely, cartridge filters tend to lose suction rapidly when clogged with fine metal dust, leading to less stable extraction performance and more frequent maintenance interventions.

For CNC laser workstations, cartridge filters have historically been the primary choice; however, in practice they suffer from rapid clogging by fine metal dust and a loss of stable suction, leading to more frequent servicing and shorter service life. For this reason, there is an increasing shift towards Jet BAG fabric baghouse filters, which offer significantly larger filtration area, more stable pressure drop, and a long lifespan of up to 20,000 operating hours, thereby maintaining constant extraction performance even under prolonged laser cutting loads.

The lifespan of filtration systems for CNC lasers varies depending on the technology used. With cartridge filters, practical life typically centres around 2,000 operating hours, as fine metal dust from laser cutting rapidly clogs the filter medium and causes a gradual loss of performance. In contrast, baghouse filters such as Jet BAG offer a significantly longer lifespan, usually around 20,000 operating hours, thanks to their larger filtration area and more stable regeneration process, which ensures consistent suction over the long term and lower running costs.

Yes, the difference between filtration systems for laser processing and conventional machining is fundamental, primarily concerning filter media loading, dust characteristics, and safety requirements. Laser cutting generates fine metallic dust and often hot particles; therefore, spark separation and stable airflow must be addressed to prevent ignition risks within the filter. Filters in this context are designed for higher and more consistent loading, with an emphasis on constant suction pressure and long-term regeneration. Conversely, conventional machining (milling, turning) produces coarser and heavier chip dust, where the risk of sparks is lower. The system focuses more on volumetric material transport than on fine filtration and vacuum stability.

Extraction in sheet metal laser cutting is essential because the process generates fumes, fine metallic dust and smoke. These contaminants impair visibility within the machine’s working area, burden optics and lenses, thereby reducing both precision and equipment lifespan. They also pollute the work environment and compromise operator hygiene. A properly designed extraction system therefore protects the laser technology itself, cut quality, as well as operational safety and comfort.

Fine metallic dust generated by laser cutting is managed through multi-stage filtration, where the Jet BAG cartridge filter system plays a key role. Thanks to its large filtering surface and stable regeneration capability, it can effectively capture very fine particulate fractions over the long term without significant pressure drop. The dust is collected on the filter medium and then systematically cleaned into a hopper, from which it is transferred for further handling. With proper system design and sufficient filtration efficiency, the cleaned air can be safely recirculated back into the hall, improving the facility’s energy balance and reducing heat loss.

Spark extraction for CNC lasers is addressed by installing a spark separator positioned before the filtration unit. This device captures or cools hot particles generated during cutting before they enter the filter, significantly reducing the risk of damaging the filter media or causing a fire within the filtration chamber. In practice, this is a key safety component that complements the filtration process itself and ensures stable and safe operation of the entire extraction system.

Yes, a spark arrester is essential for laser extraction as it significantly reduces the risk of ignition in the filtration unit when hot particles generated during cutting are drawn in. In practice, this is a key safety component that protects the filter, extends its lifespan, and enhances the overall reliability of the extraction system.

Fire protection for CNC laser filters is addressed through a combination of measures within the extraction ductwork and prior to the filtration unit itself. The foundation lies in maintaining an adequate transport velocity in the piping, typically around 18–20 m/s, which ensures that any sparks tend to extinguish before reaching the filter. Furthermore, the system is designed with sufficient pipe length between the machine and the filter to allow for cooling and complete combustion of particles. A key safety component is also a spark separator installed upstream of the filter, which captures or neutralises residual hot particles and significantly reduces the risk of igniting the filter media. Consequently, the entire system operates as a combination of correct flow dynamics, structural spacing, and active filter protection

Air recirculation in laser workstations operates by extracting air, passing it through a filtration unit (typically a Jet BAG) to thoroughly remove fine metal dust, and then returning the cleaned air back into the production area. In a correctly designed system, the outlet is further purified via an exit filter layer or diffuser elements, ensuring uniform and draught-free dispersion of air throughout the hall. This approach significantly reduces heat loss, improves the energy efficiency of operations, and maintains stable air quality in the working environment.

Yes, cleaned air can be recirculated back into the hall for CNC laser workstations if the filtration system is correctly designed and ensures sufficient efficiency in capturing fine metal dust. In practice, jet bag filter systems are used, which allow stable capture of very fine particles, thereby enabling safe operation in recirculation mode. It is important that the exhaust air is not only cleaned but also evenly dispersed back into the space to avoid drafts and prevent localised concentrations of pollutants. Recirculation is commonly used in both winter and summer modes as it significantly reduces the building’s energy losses.

The advantages of recirculation in CNC lasers lie primarily in heat savings during the winter months, as the cleaned air is returned to the hall, reducing the building’s heat losses. At the same time, it is important to note that the laser itself and the cutting process are significant sources of heat; therefore, exhausting this air outdoors would result in unnecessary energy losses in practice. Another benefit is the stabilisation of the internal environment within the hall. Since the recirculated air has already been freed from fine metal dust, it improves workplace cleanliness and reduces dust levels throughout the facility. Overall, this represents an efficient solution both energetically and operationally, provided that the filtration system is correctly designed.

The typical errors in designing laser extraction systems mainly involve the incorrect choice of filtration technology, under-sizing of power capacity, and inadequate solutions for maintaining stable suction over time. A common mistake is the use of cartridge filters, which rapidly lose efficiency during a shift; their vacuum fluctuates, and they fail to maintain consistent extraction performance over the long term when dealing with fine metal dust from laser cutting.

Other errors include under-sized airflows, poorly designed suction distribution for larger laser tables, and the absence of spark separation, which increases the risk of filter damage or fire. Another issue is insufficient reserve filtration area, leading to rapid clogging and a decline in overall system performance.

The difference between cartridge and hose filters for CNC lasers lies primarily in their construction and the filtering media used. A cartridge filter features a compact design with a large filtration area within a relatively small footprint, making it a cost-effective investment; however, in practice, this leads to rapid clogging by fine metal dust, fluctuating pressure drop, and a gradual loss of suction power throughout the shift. Conversely, a hose (textile) filter, typically a Jet BAG, offers a smooth filtration surface without the pleats found in cartridge filters. It provides more stable regeneration via JET pulses, thereby maintaining consistent vacuum levels over the long term even under high loads from laser dust. From an operational perspective, while it requires a higher initial investment, it is significantly more stable and has a longer service life.

Cartridge filters are unsuitable for certain laser processing environments primarily because laser cutting often operates in continuous 24/7 mode, generating very fine and constant metal dust that rapidly clogs the filter surface of cartridges. This leads to a rapid increase in pressure drop, fluctuations in suction performance, and the need for more frequent regeneration or replacement of filters, which practically limits operational stability.

For continuous laser lines, therefore, stable vacuum and long-term constant extraction performance are essential—capabilities that cartridge filters cannot maintain at the required standard, whereas hose-based Jet BAG systems manage this effectively thanks to their unrestricted filter area and more stable regeneration process.

Maintenance of filtration units for CNC lasers is very low-maintenance when the system is correctly designed; in practice, it involves mainly preventive checks rather than routine servicing. Typically, this consists only of occasional visual inspections of the filter condition, seal integrity, and regeneration function. Thanks to the stable operation of Jet BAG hose systems, the unit maintains constant pressure losses over the long term without requiring frequent intervention. The actual replacement of filter bags is usually carried out after approximately 20,000 operating hours, depending on usage intensity and the type of material being cut, ensuring low operational costs and high technology availability.

The fire risks associated with laser machine extraction systems are primarily driven by the presence of hot particles, fine metal dust, and flammable residues generated during cutting. If the system is not properly designed—specifically regarding sufficient pipe length to cool particles, appropriate transport velocity (approximately 18–20 m/s), and the installation of a spark separator—hot particles may reach the filtration unit and ignite the filters. The risk increases significantly with inadequate maintenance, blocked ductwork, or underpowered extraction, where particles can accumulate and create local ignition sources. Therefore, in practice, it is essential to combine correct system aerodynamics, spark protection, and a stable operating regime.

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Extraction during aluminium cutting

Vacuuming when cutting aluminium is distinct primarily due to the production of light swarf and fine dust, which tend to bridge in ductwork and hoppers and adhere to surfaces. Consequently, the entire system must be designed to ensure maximum flow smoothness and eliminate any areas where material could become trapped. Smooth piping with flanged joints is used to minimise turbulence and material deposition, while a Flat WOOD filter unit featuring double spacing handles volumetric loading and the variable nature of aluminium swarf more effectively. The hopper is engineered with a focus on active material discharge, often incorporating an auger screw to prevent bridging and a large rotary feeder for consistent removal. The entire system is complemented by correctly adjusted filter regeneration, with a filter construction that avoids unnecessary reinforcements to prevent swarf accumulation and ensure optimal material extraction.

The difference in extracting aluminium swarf compared to steel is fundamental, primarily due to the nature of the material produced. With aluminium, long and light chips are predominantly generated, often from sawing or machining operations; these tend to clump together, arch, and form so-called “blankets,” which significantly complicates flow through ductwork and removal from filters. Therefore, it is essential to design smooth duct runs, generous cross-sections, and discharge points with active material extraction (e.g., auger conveyors and large rotary feeders). Conversely, steel processing mainly produces fine, free-flowing dust or swarf, which behaves more stably, falls better, and has less tendency to arch. Consequently, the extraction system for steel focuses more on dust filtration, whereas for aluminium, addressing the mechanical behaviour of the material and its transport is key.

The design of aluminium swarf extraction systems is primarily determined by the number of extraction nozzles on the machine and the required transport velocity within the ductwork. For aluminium swarf, this typically ranges between 22–24 m/s to prevent settling and bridging. Based on these parameters, the total extraction capacity is established, and duct dimensions are selected to ensure stable transport even under variable loads. Equally important is the correct specification of the filtration unit; for aluminium applications, the Flat WOOD design has proven effective as it handles bulk material efficiently and allows larger swarf particles to pass through smoothly without risking system blockages.

The specific characteristics of aluminium swarf in terms of ATEX depend primarily on their shape and grain size. In the case of coarse chips and turnings from machining operations, these are relatively large fractions with a low propensity to form explosive dust atmospheres, as they do not disperse easily into the air and fail to create a stable aerosol.

For this reason, in the context of standard aluminium swarf generated by chip-based machining, ATEX risk is often significantly reduced or, in practice, is not treated as a primary design factor for extraction systems. Conversely, a different situation arises with fine aluminium dust (from grinding or fine cutting), where ATEX considerations are indeed crucial.

Therefore, the key issue is not merely “aluminium” itself, but rather particle size and shape – swarf is generally safer, whereas fine dust presents a critical hazard.

Arching of aluminium swarf in hoppers is primarily addressed through structural and mechanical design, as this material tends to clump together and form stable “bridges”. The foundation lies in a hopper with a flat or steeply inclined base, which minimises areas where material can become trapped.

Additionally, active arch breaking is achieved using a rotary excavating cutter, which continuously disrupts the material and ensures its smooth flow towards discharge. This system is often combined with a large rotary feeder, which stabilises the hopper outlet and prevents air suction back into the system.

In certain applications, the hopper discharges directly into a large-volume container, which also functions as a closed collection system and helps maintain a steady material flow without arch formation.

For aluminium shavings, filters are used that are structurally adapted for bulk and bridging materials, as conventional dust extraction solutions often fail in this context. Robust hose filters with a large flow profile and an open discharge point have proven particularly effective, enabling smooth transport of shavings without clogging the system.

In practice, the Flat WOOD design has proved highly successful; it is specifically engineered for processing aluminium shavings in automated lines where consistent airflow stability, minimal risk of bridging, and the ability to handle variable volumetric loads are critical. This filter type is often combined with active material removal systems (such as rotary feeders or scraping mechanisms) to ensure seamless operation of the entire system.

Exactly – for aluminium swarf, cartridge filters are not recommended primarily because their complex pleated structure allows the swarf to easily catch and gradually “clog” the filter media. These deposits are difficult to release even during regeneration, leading to a permanent reduction in permeability and loss of suction performance.

In practice, this results in rapid fouling, uneven regeneration, and the need for frequent maintenance or replacement, which is a significant issue with aluminium swarf that tends to clump and bridge. Therefore, more open textile systems are preferred for these applications, where there is no place for the material to “jam” and it can fall freely into the hopper.

Filter regeneration for aluminium swarf is handled through automatic cleaning using compressed air pulses, known as JET regeneration. This process regularly dusts off the filter surface at set intervals, maintaining stable system permeability.

However, in aluminium applications, it is crucial that regeneration is correctly configured and sufficiently intense. Swarf tends to clump and adhere mechanically, meaning that gentle dusting alone may not always be adequate. Therefore, this process is often combined with specific filter design features and discharge chutes to ensure smooth material flow and prevent a loss of suction performance.

For Jet BAG filters used with aluminium swarf, pulse regeneration using compressed air (JET system) is the most suitable method. This operates in short, controlled pulses to ensure regular dust removal from the filter surface without clogging. With aluminium, it is crucial that regeneration is sufficiently dynamic and stable, as the material tends to clump and adhere mechanically. Correctly set pulses help maintain a constant pressure drop and ensure smooth filter operation even under variable swarf loads.

Preventing filter blockages when cutting aluminium is primarily determined by the overall system design, as the greatest risk does not lie in filtration regeneration but in the mechanical behaviour of the material. Critical areas are mainly the discharge point, where bridging of shavings can occur, and the internal structural components of the filter, around which material may become trapped. Therefore, an open and smooth design is proposed, free from unnecessary reinforcements and featuring continuous transitions that prevent material accumulation. Regeneration using compressed air plays a merely supportive role here, as with larger aluminium swarf and chips, the main issue is not fine dust but their volumetric and mechanical behaviour within the system.

Typical issues associated with the extraction of aluminium swarf are primarily linked to its shape instability and tendency to mechanically “tangle” within the system. Arching often occurs in the extraction ductwork, particularly at changes in direction or areas of lower flow velocity. Another common problem is bridging in the filter hopper, where swarf accumulates and forms bridges that impede the smooth discharge of material.

In filtration units, material can also become trapped within structural components, which hinders its removal and leads to uneven loading on the filter. Clogging or “plugging” of the hopper is also problematic when finer dust combines with longer swarf, causing the material to bind together.

Local blockages may then develop in the ductwork, particularly at inappropriate flow velocities or transitions where swarf begins to become mechanically trapped and gradually forms a complete blockage across the entire cross-section. Overall, this is more a matter of the mechanical behaviour of the material than classic filtration issues.

Large chunks of aluminium swarf are generally not considered an issue in properly designed filtration systems, as the system itself—particularly for Flat WOOD applications or robust Jet BAG filters—is dimensioned to handle voluminous material. These swarf pieces are not detrimental to the filter provided that a continuous flow is maintained and the discharge mechanism is correctly designed. The key is to prevent accumulation at critical points such as pipe transitions or discharge hoppers. Therefore, the focus is on system construction—smooth piping, large cross-sections, and active discharge mechanisms—rather than attempting to “capture” swarf within the filter itself. Consequently, the filter is designed to allow large chunks to pass through without issue, ensuring they are continuously removed by a rotary feeder or mechanical discharge unit.

The structural elements of filters for aluminium swarf are designed in a highly specific manner precisely due to the risk of bridging and material wrapping. Only external shell reinforcements are used, which ensure the static strength of the entire structure; however, no conventional internal supports or obstacles are incorporated within the filtration chamber. This is purely an operational consideration: aluminium swarf tends to catch on any internal component, gradually enveloping it and forming continuous deposits (blankets) that subsequently reduce permeability and lead to complete system blockage. Therefore, the interior of the filter must be as open and smooth as possible, free from any elements that could initiate material entrapment. Structural integrity is thus addressed exclusively from the outside, while the internal geometry is designed to promote free falling and a smooth discharge of swarf into the hopper.

The requirements for the discharge chute in aluminium chip extraction are primarily driven by the need to prevent bridging and material accumulation, as chips tend to mechanically tangle and form arches. In practice, two proven concepts are used. The first is a very sharp, steep discharge chute with no internal cross-bracing, ensuring that chips have nothing to catch on and can fall freely into the extraction line. The second option features a shallower slope supplemented by active agitation, most commonly using a rotary digging auger or similar mechanism, which prevents arch formation and ensures a consistent material flow. In both cases, it is crucial for the discharge chute to be as structurally “clean” and smooth as possible, with no internal components that could initiate chip entanglement and gradual system blockage.

The removal of material from the filter in aluminium applications is most commonly addressed using a rotary feeder, which ensures smooth and sealed discharge of shavings or dust from the filter hopper. The material is then either directed into a container or a big bag, or – in modern lines – directly into a briquetting press for further processing and compaction.

It is crucial that the removal process remains stable without drawing in false air, as aluminium shavings tend to arch and create irregular flows; therefore, the rotary feeder must be correctly sized and structurally robust.

Typical airflows for aluminium cutting extraction in automatic lines typically revolve around 4,000 m³/h per technological unit. This corresponds to the common configuration of extraction nozzles with diameters D80, D100, D125 and D150.

The system is designed to maintain a transport velocity of approximately 24 m/s, which is crucial for reliable aluminium chip conveyance and preventing deposition or bridging in the pipework. The total capacity is always adjusted to the specific route length, number of nozzles and characteristics of the cutting line; however, 4,000 m³/h is a very common standard in practice for automated lines.

When cutting aluminium, spark separation is generally not required because this process typically does not produce the hot sparks associated with steel.

Although fine dust and swarf are generated, the process is primarily mechanical and thermally stable; consequently, the risk of transporting hot particles to the filter is significantly lower than when cutting steel or during grinding operations.

The service life of filter elements when extracting aluminium dust in correctly designed systems, such as the Flat WOOD model, typically reaches 20,000 operating hours and beyond. This is primarily due to a suitable filter design featuring ample filtration area, stable regeneration, and airflow management that prevents local overloading or chip accumulation in critical areas. For aluminium applications, the mechanical behaviour of the material is more significant than chemical stress on the filter; therefore, with proper system design, filter elements achieve a very long service life.

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Extraction of recycling plants

The nature of dust in recycling facilities is typically heterogeneous and highly variable, as it originates from various materials and processes simultaneously. It contains a mixture of fibrous components, fine dust, and larger chunky particles, such as plastic bag remnants, polystyrene, foam, films, or textile fibres. This type of dust exhibits significantly different behaviour compared to conventional free-flowing powder; it tends to wrap around surfaces, bridge, form clumps, and irregularly clog ductwork and filtration equipment. From a suction system design perspective, it is therefore essential to account for variable loading, higher volumetric instability, and the need for robust filtration systems capable of handling both fine and coarse fractions in a single operation.

The differences in dust composition across various recycling lines are primarily determined by the input material. However, fundamentally, it is always a heterogeneous mixture of fibres, fine dust, and particulate matter that behaves more like a felt-like mass than conventional bulk powder. In plastic recycling lines, lightweight fractions such as films, carrier bags, and foams (polystyrene, sponge) predominate. These generate highly voluminous, fibrous, and electrostatically active dust. In paper and cardboard recycling facilities, cellulose fibre dominates; this material tends to produce high levels of airborne dust and causes filter blockage at higher humidity levels. Conversely, metal recycling plants exhibit a greater proportion of heavier abrasive particles, fine metallic residues, and crushing dust. Although the ratio of individual components varies, a common characteristic across all recycling lines is this felt-like structural behaviour of the material. This leads to bridging, winding around machinery components, and uneven loading on filtration systems.

Recycling facilities handle an extremely wide range of materials, processing virtually everything from waste electrical and electronic equipment (WEEE) and white goods to end-of-life vehicles and municipal solid waste. Consequently, the material is always an extremely heterogeneous mixture of various components, where significant quantities of light fraction are produced alongside heavy metallic and plastic parts. This light fraction behaves similarly to dust—it contains fine plastics, films, carrier bags, foam materials (such as polystyrene and sponge), and textile fibres. This component is critical for extraction purposes because it is highly voluminous, fibrous, and easily becomes airborne. Overall, recycling facilities typically do not generate a single uniform “dust” but rather a mixture of various fractions, where the light, fibrous portion dictates behaviour within the extraction and filtration system.

Yes, we can handle separation lines for end-of-life vehicle recycling as a comprehensive project—from process design and engineering documentation through to the manufacturing and supply of technology, installation, commissioning, and start-up. We already have specific implementations in this field, so we are well acquainted with the specifics of both light and heavy fractions, dust generation, and the variable nature of materials throughout the entire end-of-life vehicle processing workflow.

The extraction of paper and cardboard in recycling plants is typically addressed through a combination of mechanical separation followed by filtration. Material from the shredder is drawn away by a transport fan, which ensures steady conveyance of the lightweight fibrous fraction to a cyclone separator where coarser particles are separated and flow stabilised. Subsequently, the fine dust and fibrous components are further purified in a filter unit, most commonly of the Flat WOOD type, which is suitable for the volumetric and fibrous materials typical of paper recycling. This system enables stable operation even under variable loads and ensures effective separation of reusable fractions from fine dust.

Plastic grinding dust is distinctive primarily because it is very light, dry and highly electrostatically active, which significantly affects its behaviour within the extraction and filtration system. It forms a very fine fraction with low bulk density and often creates a “fluffy” filter cake that paradoxically exhibits very low pressure drop; consequently, the filter does not show a significant increase in differential pressure (DP) even as it gradually becomes clogged.

This is precisely the problem: conventional regeneration control based on pressure drop may respond with a delay or not at all, leading to gradual accumulation of fine plastic dust within the filter without any obvious alarm. Therefore, for these applications, it is essential to combine DP-based regeneration control with time-based schedules or operational experience.

The specific characteristics of dust from metal crushing in recycling lines are primarily determined by its high abrasiveness, variable structure, and the safety risks associated with enclosed cavities (e.g., tanks). The material is a mixture of fine metallic dust, shavings, and oxide particles, which significantly wear down pipework, cyclones, and filtration systems. In some cases, crushing enclosed units (such as gas or petrol tanks) can lead to pressure surges or explosion effects. This requires system design with a strong emphasis on safety—namely, robust Hardox-lined cyclone separators, reinforced pipeline routes, and protection against pressure shocks. A wet cyclone with water spray is often used as the final stage; this stabilises the fine fraction while simultaneously reducing the risk of secondary dust generation. The entire system must also include pressure relief panels (explosion vents) on cyclones, pipework, and rotary feeders to ensure controlled venting of any potential overpressure and protect the technology. Overall, this is a highly demanding application where abrasive wear, variable material particle size, and heightened safety requirements are combined.

The extraction of recycling lines is always designed as a comprehensive system based on the detailed identification of all dust sources, particularly crushers, sorters, transfer points, and air separators. Each of these points is assessed in terms of dust intensity and operational mode before being connected to a central pipework network. This network is dimensioned to handle variable loads and is often constructed with robust specifications to accommodate the fibrous and heterogeneous nature of the material, for instance using a Flat WOOD system design. The design also incorporates ATEX safety measures, as explosive dust atmospheres can occur in recycling facilities depending on the material being processed. The extracted air is then routed through filtration units and, once cleaned, discharged outdoors via exhaust stacks, with the option of heat recovery where required by the specific project. The entire system must be engineered to remain stable despite fluctuations in performance while ensuring resistance to blockages and mechanical stress.

Typical airflows in recycling plants vary depending on the technology type and dust intensity. Crushers typically require 8,000–10,000 m³/h, while sorters are usually extracted at 3,000–4,500 m³/h. Conveyor drop points demand approximately 1,000–1,500 m³/h per point, and receiving hoppers represent the most heavily loaded areas, requiring around 10,000–15,000 m³/h. The entire system is subsequently integrated into a central extraction network capable of handling the variable nature of the light, fibrous, and heterogeneous fractions typical of recycling lines.

Robust cartridge (tube) filters with large spacing between filter elements are primarily used in recycling lines, as they handle the heterogeneous and fibrous nature of dust typical in recycling plants more effectively. These filters are often equipped with a pre-separation chamber that relieves the main filtration section from coarse fractions and reduces the risk of clogging.

The design typically includes a flat discharge hopper with active material removal, such as via a digging auger, to prevent bridging and the settling of light and fibrous particles. To ensure smooth discharge, a large rotary feeder is used to stabilise material output and prevent air suction into the system.

Given the nature of the material and the potential for explosive dust atmospheres, these filters are often designed in ATEX versions, including appropriate safety features, explosion relief, and grounding of the entire technology.

Large filtration areas are not primarily used in recycling plants to reduce pressure drop, but rather to maintain low air velocity within the filter, which is critical for this type of light and fibrous dust. In most cases, the dust cake does not form a dominant pressure barrier; therefore, the filter can operate effectively even at higher superficial gas velocities, typically around 2 m³/m²/min.

The key factor is ensuring that airflow within the filtration chamber remains calm and low-velocity. Light fractions (such as films, fibres, and foam) tend to remain suspended rather than falling into the hopper. If the air velocity is too high, these materials are re-entrained into the airstream, compromising separation efficiency.

Consequently, a large filtration area does not serve to reduce pressure drop but to ensure proper aerodynamics within the filter, allowing light and bulky fractions sufficient time to settle and fall safely into the discharge system.

The variable nature of dust in recycling lines is primarily addressed by robustly sizing the system for the worst-case operational scenario, namely the combination of maximum dustiness, the lightest fraction, and the highest volumetric load. This is crucial because material composition changes significantly over time – ranging from heavier, free-flowing fractions to very light, fibrous, and bulky components (films, fibres, foams). For this reason, design is based on peak conditions rather than averages, ensuring the system can handle situations with the lowest bulk density and highest particle entrainment. This guarantees stable suction performance, correct sedimentation of light fractions within the filter chamber, and overall operational reliability even under highly fluctuating loads.

The most common issues associated with suction in recycling lines primarily relate to the unsuitable design of filtration units for heterogeneous and fibrous materials. Filters with small gaps between filter elements are particularly critical, as they lead to rapid clogging and restricted airflow when handling light and bulky fractions. Conical or V-shaped hoppers are also problematic, as they promote bridging and uneven discharge of fibrous material. Another frequent issue is the use of cartridge filters, which quickly become blocked in recycling facilities and struggle to handle volumetric dust consistently. The arrangement with air intake from above between filter elements is also unsuitable, causing uneven airflow, poor separation of light fractions, and their re-entrainment within the system.

Filter clogging in recycling plants is primarily addressed through automatic regeneration using compressed air pulses, i.e., the classic JET system, which continuously cleans the filter surface and maintains stable operating pressure drop. However, for recycling lines it is important that regeneration is not the sole control element, as dust characteristics can be highly variable and are often light and fibrous. Therefore, regeneration is combined with specific filter design features – a large filtration area, low air velocity, and a correctly designed hopper that allows material to flow smoothly without re-entrainment or bridging.

The extraction of light fractions, such as films and plastic bags, is managed by ensuring that the suction itself is not an issue; rather, the critical factor is separating these materials before they enter the filtration unit. Therefore, a rotary separator or pre-separation stage is often employed to capture bulky and lightweight items, preventing them from entering the pipework and filter. This significantly stabilises the entire system, as only finer fractions reach the filter, allowing the filtration unit’s design to be simpler and better optimised for stable operation. This approach also reduces the risk of films winding around in the pipes, bridging occurring, and uneven loading of the filtration chambers.

The removal of heavy and abrasive fractions is primarily addressed by maintaining sufficient transport velocity within the pipeline to prevent sedimentation and gradual system blockage. In practice, a higher flow velocity, typically around 24–25 m/s, is therefore designed to ensure reliable transport even of heavier particles.

At the same time, it is necessary to address high mechanical stress on the piping, particularly at bends and elbows where erosion is most severe. Consequently, reinforced or double-walled elbows are used, along with wear-resistant linings that protect the pipeline against abrasion from the material. The entire system must be designed to combine appropriate flow velocity with sufficient mechanical resistance in each section of the pipeline route.

The difference between extracting plastics and metals in recycling is fundamental, as the nature of the material, along with the associated risks and overall technological approach, differs significantly. With plastics, we typically deal with a lightweight, bulky, and fibrous fraction that transports well through air, has low mass, and presents relatively straightforward separation requirements. The main challenges lie rather in material variability, electrostatic charge, and the tendency to wrap around components; however, from a filtration perspective, this represents a more 'airy' and stable application. Conversely, with metals, the situation is considerably more complex—an ultra-heterogeneous mixture of dust, swarf, abrasive particles, and often oil vapours is generated. This results in higher mechanical stress on the system, along with risks of sparks, local overheating, and potential explosive behaviour from fine fractions. Consequently, the technology must be significantly more robust, often multi-stage (involving cyclones, separation, filtration, and sometimes wet stages), addressing both abrasiveness and operational safety aspects.

The explosivity of dust in recycling plants (ATEX) is addressed as a fundamental safety aspect of the entire system, as light and fibrous fractions can create an explosive atmosphere within both the pipework and the filtration unit. The design therefore incorporates multiple levels of protection – welded pressure-resistant piping, B-Flap type explosion propagation prevention devices, an antistatic configuration for all system components, and correctly designed explosion venting areas that discharge into a safe, clear space outside the process technology.

Filtration units are engineered in ATEX-compliant versions tailored to specific operational zones, including earthing, antistatic media, and structural elements that minimise the risk of ignition initiation as well as the propagation of explosions into other parts of the plant. The entire system is thus conceived as a controlled safety chain, where each component has a defined function in the event of a pressure incident.

For 24/7 recycling plants, robust hose filter systems are suitable. Designed for variable, fibrous and heterogeneous dust, they can operate long-term at stable negative pressure and high volumetric load. In practice, the Flat WOOD type has proven very effective; it is designed for continuous operation, large volumes of light fractions and stable separation even when input material fluctuates. The key element is the use of a flat hopper with active material discharge, for example using a digging milling machine, which prevents bridging and accumulation of fibrous components. Another important feature is the larger spacing between filter elements (double gaps), which reduces the risk of blinding and improves sedimentation of light fractions in the filter chamber. Overall, this is a system designed for long-term continuous operation, minimal downtime and stable performance even with significantly variable recycling material characteristics.

The discharge of material from filters in recycling lines is managed to ensure a smooth flow, preventing bridging and the winding of fibrous components. Consequently, an excavating screw conveyor is frequently employed at the discharge point to actively break up the material and prevent accumulation.

Unlike bucket elevators, which are not recommended for these applications due to the risk of fibre wrapping and chain blockages, a simpler and more open discharge mechanism is preferred. The material is then metered through a rotary feeder equipped with rubber or sealing strips, ensuring consistent discharge without air entrainment.

The entire system is typically connected to a belt conveyor that transports the material into containers or for further processing. This ensures stable operation even when handling highly problematic fibrous and heterogeneous fractions typical of recycling lines.

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Fans

The fan is the heart of the extraction system and, in filter units, it is positioned downstream of the filter to ensure that the entire system operates under negative pressure. By means of a variable frequency drive, it maintains the set negative pressure at the filter inlet, ensures stable operating conditions for the boiler or furnace, and simultaneously overcomes pressure losses across the pipework, filtration unit, and other system components. This guarantees constant extraction performance and reliable operation of the entire technology.

The fan is the heart of the extraction system and, in filtering units, is typically positioned downstream of the filter to ensure the entire system operates under negative pressure. Using a variable frequency drive, it maintains the set negative pressure at the filter inlet, overcomes pressure losses in the pipework, filter unit, and other components, and ensures constant extraction performance. This allows the entire system to operate stably and reliably, regardless of the number of active extraction points or current operating conditions.

There are many types of industrial fans, such as axial, radial or diagonal. However, for extraction and filtration systems we practically exclusively use radial fans. These are capable of overcoming high pressure losses in ducts, filtering equipment and other components, ensuring a stable airflow throughout the system.

The main difference between radial and axial fans lies in the achievable pressure. Axial fans are designed for high air volumes with very low pressure losses. Radial fans, on the other hand, can generate significantly higher pressures to overcome resistances from ductwork, filtration units, and other components. Consequently, radial fans are used almost exclusively in extraction systems.

Radial fans are suitable wherever higher pressure losses need to be overcome. They are typically used in extraction and filtration systems where the operating pressure ranges from approximately 1,500 to 10,000 Pa. Thanks to their design, they can reliably overcome the resistance of ductwork, filtration units, separators and other components, ensuring stable extraction performance.

Axial fans are suitable wherever large volumes of air need to be moved against very low system resistance. Typical applications include building ventilation, hall exhaust, roof-mounted fans or small extractors where the air flows through short ductwork directly into the outdoor environment. If there is no filter or other components with higher pressure loss in the system, an axial fan represents a simple and economical solution.

The required fan power is determined by the air volume flow rate, the system’s total pressure loss, and the fan efficiency. The basic relationship is: power × pressure / efficiency. The calculation itself is relatively straightforward. Much more important is correctly determining the required airflow and accurately calculating the pressure losses in the ductwork, filter, and other components. Errors in these figures result in a fan that is either undersized or unnecessarily oversized.

The required fan pressure is determined as the sum of the pressure losses across the entire extraction system. The calculation includes the intake hood, suction ducting, filtration unit, discharge ducting, and potentially also a discharge sleeve, silencer, or other components. The fan must overcome the resistance of all these parts while ensuring the specified air volume flow rate. For small systems with short duct runs, this is at least 2800 Pa; for longer duct runs, it typically amounts to 4000 Pa.

The operating point defines the flow rate and pressure at which the fan will actually operate. It is formed by the intersection of the fan characteristic curve and the pressure loss of the entire extraction system. If the operating point shifts, the actual air flow rate, motor power consumption, and fan efficiency will also change. Therefore, correctly determining the operating point is essential for the efficient and reliable operation of the entire extraction system.

The fan characteristic is a graphical representation of the relationship between air flow rate and the pressure that the fan can generate. From the characteristic, it is possible to determine at what flow rate, pressure, efficiency, and power input the fan will operate. It is precisely the intersection of the fan characteristic and the extraction system characteristic that determines the actual operating point of the fan.

As speed decreases, the volume of air drops linearly and pressure with the square. This is why frequency converter control is so effective. Even more interestingly, motor power consumption falls with the cube of the speed, meaning that even a small reduction in speed delivers significant energy savings.

The variable frequency drive (VFD) enables smooth adjustment of fan speed according to the system’s current requirements. It typically controls the fan to maintain the desired negative pressure or air flow rate. In central extraction systems, the speed automatically adapts to factors such as the number of open dampers or the immediate pressure drop across the filter. This ensures that the fan operates only at the power level actually required, resulting in significant electrical energy savings and stable system operation.

Fan speed regulation using a variable frequency drive primarily delivers significant electrical energy savings, as the fan operates only at the power level required at any given moment. At the same time, it reduces the system's average pressure loss, which leads to reduced loading on filter media and extends their service life. Other benefits include lower noise levels, smooth starts, and overall more stable operation of the extraction system.

The electrical energy consumption of the fan can be most effectively reduced by using a variable frequency drive and an appropriately selected control method. The fan then operates only at the power level actually required at any given moment. Regulation is typically based on the desired negative pressure, air flow rate, or number of open dampers. This approach enables significant electrical energy savings while simultaneously extending the lifespan of both the filter media and the entire extraction system.

The efficiency of a fan can be improved primarily by selecting the right unit and operating it within its optimal working point. If an existing fan operates far from its peak efficiency zone, replacing it with a more modern model featuring a more suitable performance curve is usually the best solution. Proper ductwork design, minimising unnecessary pressure losses, and using a variable frequency drive also have a significant impact on efficiency.

An undersized fan is most often identified by the fact that it runs continuously at maximum speed yet fails to deliver the required airflow. The fan operates at full capacity, with the variable frequency drive showing 100%, but the extraction performance gradually declines. A typical symptom is also high pressure loss and an inability to achieve the desired vacuum within the system.

An oversized fan is identified by operating outside its optimal duty point. It often has to be significantly throttled or runs at very low speeds where it no longer achieves good efficiency. In some cases, aerodynamic instabilities may occur, accompanied by a characteristic siren-like or howling noise. Such operation is not energy-efficient and can lead to increased stress on the fan.

The most common cause of high electrical energy consumption in fans is outdated design. A typical example is older belt-driven fans, where losses occur due to V-belts. Another frequent issue involves transport fans with straight blades; while these are resistant to abrasive wear, they significantly lag behind modern radial fans with curved blades in terms of efficiency. High power consumption can also be caused by operation outside the optimal working point or a lack of speed control.

The most common faults in industrial fans are vibrations caused by impeller imbalance, worn bearings or deposits on the blades. Another frequent issue is a burnt-out electric motor, for example due to overload or insufficient cooling. In practice, it is also possible to encounter incorrect fan rotation direction after wiring, where the fan rotates in reverse and fails to achieve the required performance.

A damaged fan impeller most commonly manifests as a sudden change in vibration and acoustic behaviour. The fan will begin to emit unusual noise, humming or knocking, while the vibration levels increase simultaneously. These changes are often the first sign of a cracked blade, a broken section of the impeller, or deposits that have caused imbalance. Early detection of the issue can prevent more serious damage to the bearings, motor, or entire fan unit.

Worn fan bearings most commonly manifest as changes in acoustic behaviour and increased vibrations. Typical symptoms include humming, whining, or regular tapping, which progressively worsen with further wear. The best way to detect the problem early is through regular vibration measurement and trend monitoring. Thanks to predictive maintenance, bearings can be replaced before a more serious fault occurs.

Fan vibration can have several causes, but by far the most common is material buildup on the impeller. Even a relatively small accumulation of dust, grease or other contaminants will cause rotor imbalance, which manifests itself as increased vibration and a change in fan noise. Other possible causes include worn bearings, a damaged impeller, loose mounting or operation outside the optimal operating point.

The noise level of the fan may have several causes. A common reason is vibration caused by impeller imbalance, for example due to deposits on the blades or damage to the rotor. Another cause is operation outside the optimal working point. If the fan is excessively throttled, unstable airflow can occur, resulting in a characteristic siren-like noise. In extreme cases, the fan may recirculate part of the air internally, which not only increases noise levels but also reduces efficiency and places greater stress on the entire unit.

Fan noise can be effectively reduced by using an acoustic enclosure that is properly ventilated with acoustic grilles. This ensures adequate cooling of both the motor and the fan without a significant increase in noise levels. Another key element is the silencer installed on the fan outlet, which limits the spread of aerodynamic noise into the surrounding area. A correctly designed combination of these measures can significantly reduce the overall noise level of the extraction system.

Vibration of the fan can be significantly reduced through proper mounting of the entire unit. The foundation lies in correctly sized silent blocks, which prevent vibration transmission into the structure. We also recommend installing flexible joints on both the intake and discharge sides of the fan to ensure vibrations are not transmitted into the ductwork system. Regular vibration checks, or preferably online monitoring as part of preventive maintenance, should be carried out to detect emerging issues early and avoid breakdowns.

Industrial fans do not require complex maintenance. In most cases, an annual check of vibrations, inspection of the bearing condition and replenishment or replacement of lubricant in accordance with the manufacturer’s recommendations are sufficient. Regular preventive maintenance significantly extends the fan's lifespan and enables early detection of emerging issues.

With proper design and regular maintenance, the lifespan of an industrial fan typically ranges around 20 years, often extending beyond that. Key factors include routine vibration checks, correct bearing lubrication, and operation at the optimal duty point. The impeller and fan housing generally have a very long service life; over time, it is usually only the bearings or electric motor that require replacement.

The choice of impeller material depends primarily on the type of application and the abrasiveness of the conveyed material. For standard vacuum suction systems, conventional steel impellers are used, providing sufficient strength and long service life. In transport fans where intense abrasive particle action occurs, impellers made from Hardox wear-resistant steel can be employed, significantly enhancing resistance to wear.

The best way to address abrasive dust in fans is to position the fan downstream of the filtration unit. The fan then moves already cleaned air and is not exposed to abrasive particles. This significantly extends its service life and allows for the use of more efficient impellers with higher aerodynamic efficiency. Therefore, a negative pressure arrangement with the fan located after the filter is now considered standard in modern extraction systems.

The most effective way to protect fans from wear is by positioning them downstream of the filtration equipment. This ensures that the fan only handles clean air, avoiding exposure to abrasive particles. Regular maintenance is also crucial, particularly checking for vibrations and replenishing lubricant in the bearings. Thanks to these simple measures, a fan can operate reliably for decades.

Backward-curved impellers are today the most widely used type of centrifugal fan wheel in industrial applications. Their main advantage is high aerodynamic efficiency, which results in lower electrical energy consumption and reduced noise levels. At the same time, they feature a stable performance curve and operate effectively across a wide range of operating conditions. Therefore, they are an ideal choice for modern extraction and filtration systems.

Flat-blade fans have lower aerodynamic efficiency than backward-curved blade fans; however, their main advantage is high resistance to wear and the ability to transport material. Due to their design, they are suitable for conveying fans where sawdust, dust or other abrasive particles pass through the impeller. Therefore, they are mainly used in positive pressure systems and pneumatic material conveyors

Direct drive and belt drives differ primarily in efficiency and speed control. Direct drive, where the impeller is mounted directly on the motor shaft, achieves the highest efficiency and minimal losses. In a belt drive, additional losses occur due to the V-belts, leading to higher electrical energy consumption. Belt drives were previously used mainly because they allowed fan speeds to be adjusted by changing pulley diameters. Today, this function is performed much more efficiently by variable frequency drives, which is why fans with direct drive are increasingly being used.

Direct drive fans are now suitable for practically all modern extraction systems, particularly when used in conjunction with a variable frequency drive. By eliminating the belt drive, they achieve maximum efficiency, lower maintenance requirements and minimal energy losses. Furthermore, the variable frequency drive allows the fan speed to be adjusted smoothly according to the system’s current needs, thereby removing the need for pulleys to alter rotational speeds.

Belt drives are becoming less common today, as modern direct-drive fans with variable frequency drives achieve higher efficiency and require less maintenance. Nevertheless, a belt drive can be a suitable solution when it is necessary to adapt the fan’s design layout to limited space or to separate the motor from the hot air stream. In certain applications, spatial requirements may outweigh the lower efficiency of the belt drive.

The main advantage of EC fans is their integrated electronics and built-in speed control. The frequency converter is part of the motor itself, eliminating the need for an external unit. EC fans allow straightforward control via a 0–10 V analogue signal, offer high efficiency, and operate quietly. Consequently, they are commonly used in lower-power applications requiring smooth regulation.

Modernising an old fan is most commonly addressed by replacing it with a new, more energy-efficient model. Modern fans featuring backward-curved blades, direct drive and variable frequency drives achieve significantly higher efficiency, lower noise levels and require less maintenance. In many cases, modernisation can deliver substantial savings in electrical energy consumption and enhance the reliability of the entire extraction system.

The performance of the existing fan can be increased within certain limits by using a variable frequency drive to raise the speed to the required value. As the speed increases, the air flow rises linearly and the pressure increases with the square of the speed. However, before increasing the speed, it is necessary to verify the mechanical strength of the impeller, the power rating of the electric motor, and the suitability of the operating point to avoid overloading the fan or the motor.

Replacing the fan with a new unit is advisable primarily when the existing fan fails to meet required performance specifications or exhibits high energy consumption. Modern fans featuring backward-curved blades, direct drive, and variable frequency drives achieve significantly higher efficiency, lower noise levels, and require less maintenance. In many cases, the investment in a new fan pays for itself through electrical energy savings within a few years.

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Piping

Pipework for extraction systems is designed based on the inlet diameters of individual machines, their required power outputs, and the actual operational overlap. It is also crucial to correctly position the connections on the central extraction branch to ensure that distances and pressure losses are optimally balanced. The aim is to maintain the correct flow velocity within the pipework, minimise unnecessary bends, and design a system that operates stably even when the number of active workstations varies.

The pipe diameter is not determined by eye. We base our calculations on the required flow rate at a given point and recalculate the necessary cross-section for a velocity of around 20 m/s. The aim is to maintain sufficient flow speed to prevent dust deposition, while avoiding unnecessary increases in pressure loss.

The recommended air velocity in the extraction ducting depends primarily on the nature of the material being conveyed. For welding fume and aerosol extraction, a velocity of around 18 m/s is typically specified. For grinding operations and general industrial applications, we recommend approximately 20 m/s. In the wood processing industry, where sawdust, chips or larger offcuts are transported, it is advisable to increase the velocity to between 22 and 24 m/s to prevent material build-up within the ducting.

For fine dust, lower air velocities are suitable, typically around 18 m/s. Fine particles are easily carried by the air and do not settle in the ductwork. Additionally, lower velocity results in reduced pressure loss, lower electrical energy consumption, and less wear on the duct system.

For the transport of sawdust and wood chips, we recommend a flow velocity of approximately 22 to 24 m/s. This is not primarily due to the fine sawdust itself, but rather larger offcuts and pieces of material, which have greater mass and require higher air entrainment capacity. Maintaining the correct speed is essential to prevent material deposition and subsequent blockages in the pipework system.

The best way to prevent material build-up in ductwork is by maintaining the correct flow velocity and appropriately sizing the various pipe diameters. It is essential to maintain sufficient air-carrying capacity throughout the entire system. In regulated extraction systems, it must also be accounted for that flow velocity may decrease when dampers are closed. Therefore, we recommend regularly flushing the ductwork at maximum power with all dampers open, allowing the pipes to self-clean of any potential deposits.

Clogging of pipeline routes is prevented by the correct design of the entire system. The foundation lies in sufficient flow velocity, proper sizing of pipe diameters, and minimising unnecessarily sharp bends or unsuitable branches. For regulated systems, we recommend regular flushing of the pipework at maximum capacity to remove any deposits before they accumulate and cause blockages.

Pipe length does affect pressure loss, but in practice it is often less significant than commonly assumed. Local resistances have a much greater impact, particularly the number of bends, branches, reducers, as well as the end diameters of connection points and their hoses. It is precisely these components that typically account for most of the total pressure loss, while long straight pipe sections have relatively little effect.

Knees have a far greater impact on pressure drop than straight pipe sections of the same length. Each change in flow direction causes additional turbulence and increases system resistance. Therefore, when designing pipework systems, we aim to minimise the number of bends and use those with the largest possible bend radius. With abrasive materials, the number of bends is also important from a wear perspective, as the greatest stress on pipe walls occurs at these points.

Branches have a similar effect on airflow as elbows, and their impact on pressure loss is very significant compared to straight sections. Each change in flow direction creates turbulence and increases system resistance. Therefore, we aim to design branches with the smoothest possible entry, typically at an angle of 45°, or even 30° for more demanding applications or larger diameters. This reduces pressure loss, noise, and the risk of material deposition.

Piping for multiple extraction points is designed to maintain as constant a flow velocity as possible in the main branch. Consequently, the pipe diameter is progressively reduced according to the actual volume of air passing through each point. Individual connections are made using smooth branches, ideally at an angle of 45° or less, to avoid unnecessary turbulence, pressure losses and dust accumulation points.

When expanding production in stages, we recommend considering future capacities during the design of the filtration system. It is advisable to prepare spare connections within the filter and subsequently connect new technologies via separate piping routes directly from the pollution source to the filter. This ensures correct flow velocity, minimal pressure losses, and allows for production expansion without modifying existing pipework.

Optimising the pipeline network primarily involves verifying pipe diameters and flow velocities. Inappropriate sizing is often the root cause of issues. At welding facilities, we have repeatedly encountered cases where fires occurred in pipelines due to excessively low flow velocities and the subsequent deposition of flammable particles.

The most common mistake in designing ductwork is applying experience from building ventilation to industrial extraction systems. Designers are accustomed to working with flow velocities of around 12 to 14 m/s, which are suitable for transporting clean air rather than dust, sawdust or abrasive particles. The result is unnecessarily large and expensive ducting where material begins to settle, leading to blockages after a certain period.

Undersized ductwork is identified by excessively high flow velocities, often around 30 m/s and above. Such speeds result in significant pressure losses, increase electrical energy consumption, and can lead to excessive wear on the ducts and system noise. Although material does not accumulate within the ducts, operation becomes unnecessarily costly and energy-inefficient.

Oversized ductwork is identified by excessively low flow velocities. Although the system may initially perform well at extraction points and achieve the required performance, dust or other materials gradually accumulate within the ducts. Over time, this leads to duct blockage, increased pressure loss, and a subsequent decline in suction efficiency.

The choice of pipe material depends on the application and the degree to which the specific dust causes wear. For welding shops, standard SIPRO piping is usually sufficient. In wood processing facilities, we use reinforced SPIRO piping with flanges. For foundries, grinding operations, and abrasive dusts, we recommend welded thick-walled piping. There is no single correct material for all applications; the piping must be designed based on experience with the specific dust and its abrasiveness.

Galvanised ducting can be used in almost all common extraction applications, provided it is not for the food industry, the extracted gases do not chemically react with zinc, and there are no high demands for resistance to abrasive wear. Owing to its favourable price, good corrosion resistance and ease of installation, galvanised ducting represents a standard solution for most industrial extraction systems.

Stainless steel piping is primarily used in the food industry where it comes into contact with products, as well as in applications involving chemically aggressive gases. A typical example is exhaust gas from melting furnaces containing hydrogen fluoride (HF) or hydrogen chloride (HCl), which can gradually corrode standard galvanized pipes. The selection of a specific stainless steel grade depends on the chemical composition of the gases, temperature, and operating conditions.

Heavy-wall piping is primarily used for abrasive materials where intense wear occurs on the pipe walls. Typical applications include foundries, grinding plants, or the transport of abrasive dusts. Another area of use involves systems requiring ATEX explosion protection, where heavy-wall welded piping serves as pressure-resistant conduit between the filtration unit and the B-FLAP backdraft damper. Its higher strength enables it to withstand both mechanical wear and the pressure effects of a potential explosion.

Abrasive dust in pipeline networks is primarily managed by using reinforced or thick-walled piping. The most heavily stressed components are elbows and branches, where changes in flow direction cause the greatest wear. For extremely abrasive applications, such as in quarries, we employ double-wall elbows and branches, which significantly extend the lifespan of the pipework system and reduce maintenance costs.

Pipework should not be designed based solely on diameter or cost. Important criteria include not only pressure loss and flow velocity, but also corrosion and abrasive wear. For standard applications, we recommend galvanized pipework, preferably hot-dip galvanised, which offers long service life and good resistance to corrosion. With abrasive dusts, the decisive factor is primarily the pipe wall thickness. We commonly use pipes with a wall thickness of 1.5 mm, 2 mm or 3 mm depending on the degree of wear. The correct choice of material and wall thickness has a significant impact on the lifespan of the entire extraction system.

Transporting heavy particles requires higher flow velocities to prevent sedimentation within the piping. At the same time, increased abrasive wear must be anticipated, particularly at points where the flow direction changes. Consequently, elbows and branch connections are often manufactured from reinforced or thick-walled pipe, or even double-skinned configurations in extreme applications. Correctly designing both velocity and pipeline durability is essential for long-term operational reliability.

The transport of fibrous materials is one of the most demanding applications. The pipeline must have the smoothest possible internal surface to prevent fibres from catching on anything. Hot-dip galvanised pipes or pipes with a comaxit coating are ideal. Fibrous materials tend to adhere to almost everything – even a tiny flake of paint, a weld spatter, or another irregularity can gradually lead to build-up that may eventually cause the pipeline to block.

Circular ductwork offers several significant advantages over rectangular systems. Its shape results in lower pressure loss and, crucially, substantially greater resistance to vacuum stress. The circular form distributes mechanical load evenly, meaning that even with thinner walls, it exhibits higher strength than rectangular ducts. Additionally, it has a reduced tendency for dust accumulation in corners and allows for easier installation. Consequently, circular ductwork is used almost exclusively in industrial extraction systems.

Segmental ductwork is primarily used for larger diameters, with its main advantages being modularity and rapid production. Individual segments can be easily adapted to the required diameter and length, enabling swift manufacturing and installation. Due to its design, segmental ductwork is ideal for extensive industrial extraction systems where producing a single-piece solution would be technologically or logistically challenging.

Flanged joints are primarily used where higher demands are placed on the strength and sealing of the piping system. Their main advantage is the high load-bearing capacity of the joint and the ability to achieve very effective sealing. Consequently, flanged joints are standard for larger diameters, thick-walled pipes, and systems with elevated pressure requirements. They also allow for easy installation, dismantling, and potential extension of pipeline routes.

Quick couplings offer primarily simple and rapid installation of the pipework system. They significantly reduce installation time, lower assembly costs, and facilitate any subsequent modifications or dismantling of pipeline routes. The disadvantage is the higher precision required in manufacturing individual components, as the pipe end must fit precisely into the coupling. For larger diameters or thick-walled pipes, flanged joints are therefore often more suitable.

Air leaks in ductwork are prevented by properly sealing individual components. The use of suitable seals between pipe segments prevents the suction of false air, which would increase flow rate, pressure loss and electrical energy consumption. Well-sealed piping is the foundation for stable and energy-efficient operation of the entire extraction system.

For longer pipeline runs and especially in flue gas extraction systems, it is essential to account for the thermal expansion of the pipework. Changes in temperature lead to variations in pipe length, which can cause excessive stress on the structure, flanges, and supports. Therefore, compensators are installed within the system to accommodate these dimensional changes and prevent the development of mechanical strain. Correctly addressing dilations is particularly important for high-temperature applications and long pipeline runs.

Ducting in outdoor environments generally requires no special measures, and standard construction is entirely sufficient. Exceptions apply where moist air or exhaust gases are extracted. In such cases, we recommend thermally insulating the ductwork to prevent water vapour condensation and subsequent issues with corrosion, blockages, or tar deposits. Proper thermal insulation is particularly important for high-temperature and flue gas applications.

Long pipeline routes should be designed as simply as possible with the longest straight sections. The aim is to minimise the number of bends, branches and flanged joints, which increase pressure loss, raise installation costs and represent potential leak points. If a route must be long, it should at least be smooth, well-supported and free from unnecessary changes in direction.

In most industrial applications, the support of pipework is typically achieved using standard clamps positioned at intervals of approximately three metres. The spacing between supports is determined by the pipe diameter, weight, and operating conditions. For heavier or thermally stressed piping systems, it is essential to account for thermal expansion and ensure that mechanical forces are not transferred to the fan or filter unit.

Inspection and cleaning openings should be positioned in areas where increased material deposition or turbulence is expected. These are typically sections downstream of bends, branches, or other changes in flow direction. This allows the pipework to be easily inspected and cleaned when necessary without requiring dismantling. Properly located inspection openings significantly facilitate maintenance and enhance the operational reliability of the entire system.

With a properly designed extraction system, regular duct cleaning is generally unnecessary. If recommended flow velocities are maintained—approximately 20 m/s for standard applications and 22 to 24 m/s for wood and larger particles—the ducts clean themselves continuously. For systems with variable speed control, we additionally recommend periodic flushing by opening all dampers and running the fan at maximum power for a short period. This removes any deposits before they can cause issues.

Clogged piping can often be identified very simply by sound. If you tap the pipe with a metal object, clean piping produces a clear and resonant tone. In contrast, piping with a thick layer of deposits has a distinctly duller sound. Other signs may include increased pressure drop, reduced suction performance, or changes in the acoustic behaviour of the entire system.

The service life of pipework can be significantly extended through the correct selection of materials, appropriate surface protection, and proper sizing of the entire system. With abrasive materials, it is crucial to reinforce the most highly stressed areas, particularly elbows and branch connections. Equally important is selecting the correct flow velocities to prevent both material deposition and excessive wear.

Modernising existing ductwork typically begins with recalculating flow rates, air velocities and pressure losses. It frequently becomes apparent that the original ducts were designed with unsuitable diameters or velocities. In such cases, it is often more economical and technically advantageous to dismantle the old ducting and design a new route in accordance with current requirements. A correctly engineered system delivers lower energy consumption, greater reliability and an extended lifespan for the entire extraction system.

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Rotary airlocks

We manufacture rotary separators with capacities ranging from approximately 3,000 to 50,000 m³/h in the RSGG model configuration. This design features a rotor and scraper bars, engineered for the continuous separation of light and bulky fractions from the extracted air stream. This solution is particularly suitable for the paper, recycling, and printing industries, where reliable removal of trimmings and prevention of downstream filter overload are essential.

Rotary separators are primarily used in industry to prevent bulky and lightweight particles from entering the filtration system, thereby protecting the filter from clogging, uneven loading, and bridging. They also enable the separation of larger fractions that can be further processed, for example by pressing or returning them to the technological process. This significantly stabilises the entire extraction system and increases both the reliability and lifespan of the filtration technology.

The principle of the separator’s rotation is mechanical separation on a sieve. The air stream carrying material enters the unit, and everything that passes through the sieve with apertures, for example 5 mm, continues into the filtration system. Coarser particles caught on the sieve are continuously scraped off by the rotor equipped with scraper bars and subsequently fall down below the separator into the discharge hopper. This method separates bulky fractions prior to filtration, thereby protecting the filter from clogging and stabilising the entire extraction system.

Rotary separators are suitable for materials that form bulky, lightweight, and fibrous or strip-like fractions, which would otherwise cause filter or pipe blockages. They are typically used for paper strips, plastic bags, films, textile fibres, Chemlon, plastic offcuts, and similar lightweight materials generated in recycling, paper mills, or manufacturing plants. In TAP operations, they primarily serve to separate larger and problematic fractions that would otherwise impair filtration performance and cause bridging or irregular material flow.

Rotary separators are supplied within a capacity range of approximately 3,000 to 50,000 m³/h. This range covers both smaller local applications and larger industrial facilities where it is necessary to reliably separate bulky and light fractions before they enter the filtration system or as part of recycling lines.

Yes, the rotary separator is primarily used in practice as a pre-filtration stage, and it delivers its greatest benefit in this role. In facilities handling solid recovered fuels (SRF), it protects the filtration unit from clogging and bridging caused by plastics, paper scraps, and bulky light fractions that would otherwise significantly impair filter performance and regeneration. Within the printing industry, it separates paper strips and trimmings, which are subsequently conveyed to a press, while fine dust continues into the filtration system. This stabilises the entire extraction process, reduces breakdowns, and substantially extends the service life of downstream filtration.

The difference between a rotary separator and a cyclone lies primarily in their separation principles. A cyclone separates particles based on centrifugal force within the airflow and has a certain efficiency depending on particle size and mass; consequently, it always allows some fine fraction to pass through to subsequent filtration stages. In contrast, a rotary separator operates as a mechanical sieve-based separator, removing coarse fractions up to a specific aperture size—typically around 5 mm—with near-100% efficiency. These larger particles are captured, while smaller ones pass entirely into the filter. Therefore, in practice, a cyclone performs a probabilistic separation of finer particles, whereas a rotary separator serves as a definitive coarse pre-filter stage that protects the main filter from bulky materials.

Material discharge from the rotary separator is managed according to operational conditions and the level of vacuum within the system. In the simplest configuration, material falls freely into a container or directly onto a belt conveyor, provided that the plant layout permits this arrangement and there is no risk of air backflow.

In cases involving higher vacuum levels or where improved sealing is required, a rotary feeder is installed downstream of the rotary separator. This ensures smooth, airtight material discharge and prevents the ingress of false air into the system.

For more demanding applications, such as recycling lines or connections to baling presses, the separator may be mounted directly onto a pressure-sealed hopper of the baler press. Here, the material is processed in a closed loop without dust leakage.

Yes, we supply rotary separators for continuous operation, and all our designs are specifically engineered for this mode. In practice, this is primarily considered in printing presses, recycling lines, and other industrial facilities where equipment runs 24/7 without interruption. The construction, drive system, and scraping mechanism are dimensioned for long-term continuous operation, with a focus on reliability, minimal maintenance, and stable separation performance.

For rotary separators, we use a single main drive: the rotor drive via gearbox. The entire system is designed to be simple and robust, ensuring continuous operation with minimal downtime. Drive power is stepped according to equipment size, typically ranging from approximately 0.75 kW up to 5.5 kW for larger models. This straightforward concept ensures reliable performance, stable rotor speeds, and long service life even in demanding industrial applications.

The efficiency of rotary separators depends primarily on the material type, particle size fraction, and sieve settings. Generally, coarse fractions above the selected aperture size (typically around 5 mm) are separated with near-perfect accuracy. Finer particles that pass through the screen continue uninterrupted to subsequent filtration or processing stages. In practice, therefore, a rotary separator does not perform fine separation like a cyclone; instead, it functions as a highly reliable coarse pre-separation stage, capturing unwanted bulky particles almost completely.

Rotary separators are the most suitable solution for facilities handling bulky, lightweight and fibrous materials that would otherwise cause blockages or unstable operation of filtration systems. They are typically used in recycling plants, paper mills, hygiene product manufacturing (such as diapers and wipes), and generally in paper and cardboard processing lines. They are also employed in printing houses, the textile industry, and packaging facilities where trimmings, strips and light fractions are generated. Their primary role is to stabilise extraction by separating coarse and bulky material components before filtration or subsequent processes.

Yes, rotary separators are increasingly being used in recycling lines, particularly in facilities processing solid recovered fuel (SRF), where clogging of conventional filters is often caused by plastics, paper, and bulky light fractions. In these applications, they serve as a primary coarse separation stage that significantly stabilises the entire extraction system and protects downstream filtration from overload and bridging. As this is a relatively new area of application, especially within SRF facilities, experience continues to grow and individual solutions are being progressively optimised based on real-world operational data.

The rotary separator connects to the pipework system via flanged joints, typically featuring an inlet flange for connecting the extracted air, an outlet flange for discharging the air into subsequent technology, and a separate flange for removing the separated material. In certain applications, it may have multiple inlet pipes depending on the equipment layout and the number of extraction points. The entire solution is designed to be robust and leak-proof while allowing for straightforward installation and service access.

The main advantage of rotary separators is their precisely defined separation function: we know exactly what the equipment does and which material it separates. A rotary separator mechanically divides a specifically determined fraction, typically those above 5 mm, with high certainty and stability. This precision comes at the cost of pressure loss, which generally ranges from approximately 500 to 800 Pa depending on the design and operating conditions. Another advantage is the simplicity and robustness of the entire solution, as it is a purely mechanical separator without complex regeneration processes. It significantly stabilises subsequent filtration and protects it from overload by bulky materials.

The drawbacks of rotary separators lie primarily in mechanical wear, caused by abrasion on the screen due to continuous contact with the material and airflow, particularly when processing abrasive or heterogeneous fractions. Another consumable component is the rotor scraper bars, which gradually wear down and require regular inspection and replacement. Compared to simpler separation solutions, there is a higher proportion of moving mechanical parts in this design, necessitating planned servicing and close monitoring of wear conditions.

Maintenance of the rotary separator primarily involves regular inspection of mechanical components and wear parts. The foundation lies in lubricating bearings and rotor drive components according to operational intervals, ensuring smooth and trouble-free operation. Additionally, scraper (rubber) strips are regularly inspected and replaced as they gradually wear down due to contact with material. Maintenance also includes checking the sieve, sealing integrity, and overall condition of the equipment to preserve correct separation performance and prevent reduced efficiency or vibrations.

Rotary separators are manufactured from welded steel structures, most commonly using black structural steel with a paint coating for corrosion protection. In more demanding environments, stainless steel versions or special protective linings can be used, depending on the application type. Wear parts include scraper blades, which are typically made of rubber or other abrasion-resistant elastomers; in abrasive applications, reinforced versions may also be employed. The entire structure is designed to be robust, serviceable, and suitable for continuous industrial operation.

Yes, we also supply rotary valves in ATEX versions, most commonly for Zone 22. However, it is important to note that the rotary valve itself is not a closed filter element; dust merely passes through it or is mechanically separated. Therefore, the key factor is ensuring the correct ATEX design of the entire assembly, including earthing, anti-static components, and associated parts. Consequently, an ATEX solution does not address only the separator itself but the complete system—including pipework connections, drives, discharge points, and downstream technology—to ensure operational safety within Zone 22.

The design and sizing of the rotary separator are based on fundamental operating parameters, primarily the required air flow rate, its location within the process technology, and the pressure conditions at the separation point. The pressure in the separator chamber is also critical, as it influences flow stability and overall material separation efficiency. Based on these inputs, the equipment size, screen area, and rotor configuration are determined to ensure effective coarse fraction separation with minimal pressure drop and stable operation.

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Cyclone separators

We manufacture several types of cyclone separators tailored to operational conditions and customer requirements. We typically supply welded units made from black steel with a surface treatment, suitable for standard industrial applications. Additionally, we offer stainless steel versions for corrosive or humid environments, as well as painted variants according to the investor’s specifications. For abrasive processes such as wood, biomass, or TAP, we use cyclones lined with Hardox in the most heavily stressed components. A special category includes wet cyclones equipped with nozzles, which are employed where enhanced efficiency in removing fine dust or reduced outlet emissions is required.

Cyclone separators are primarily used in industry as pre-separators ahead of the main filtration unit, where they reduce dust load and protect the filter from coarse and abrasive particles, significantly extending its service life and lowering operating costs. In certain applications, they can also operate independently without subsequent filtration; for example, to separate coarse and moist sawdust in woodworking operations where high-efficiency fine filtration is not required. Another application is as a final separation stage in recycling lines, such as those processing end-of-life vehicles, where wet cyclones with nozzles are often employed to improve the capture efficiency of fine dust and reduce emissions at the outlet.

We supply cyclone separators in a standard capacity range of approximately 500 to 45,000 m³/h. In practice, however, we also design larger cyclones; the largest unit implemented to date has a capacity of 80,000 m³/h. For these large units, modular construction is typically employed, where the cyclone is divided into several sections for transport and assembly, with final completion carried out directly at the installation site. This approach enables the implementation of very high capacities while maintaining constructability and structural stability.

We manufacture cyclone separators in a range of approximately 500 m³/h to 80,000 m³/h. This range covers both smaller local applications and large industrial systems; for higher capacities, these are modular or split designs installed directly on-site.

We supply cyclones in a modular structural design that is engineered for easy transport and on-site installation. Individual components are connected via flanges, enabling precise assembly as well as serviceable disassembly. Each cyclone is standardly fitted with three main flanges – inlet, outlet, and discharge for the removal of separated material – and is also equipped with feet for mounting onto a steel support structure. This design is robust, proven in industrial applications, and allows adaptation to specific operational conditions.

Yes, we supply welded cyclone separators; all our cyclones are designed as fully welded, robust units intended for industrial use. We do not manufacture thin-walled or lightweight constructions, as they fail to meet requirements in terms of lifespan, sealing integrity, and operational stability in demanding applications.

Yes, cyclone separators can be supplied in stainless steel and this is standard practice where it makes technical sense. Typically, these are wet cyclones which are always made of stainless steel due to corrosion risks and operation with a water phase, as well as applications in the chemical industry or aggressive environments where stainless steel is the norm. We have also implemented stainless steel versions for boiler applications, although this is not always a mandatory requirement but rather an investor’s request or specific operational condition.

The efficiency of cyclone dust separation typically ranges from approximately 80% to 95%, depending on the type of dust, its particle size distribution, and operating conditions. For heavy and easily separable dust, such as that generated by filing or wood waste, efficiency can reach around 99%; however, these are rather specific cases. Conversely, efficiency decreases with very fine or light dust because cyclones operate on a mass separation principle and struggle to separate fine particles centrifugally. Overall, the lighter and finer the dust, the lower the cyclone’s efficiency, which is why they are often combined with subsequent filtration stages.

Cyclones are particularly suitable for heterogeneous and coarser dusts, where mechanical separation must be carried out before fine filtration. In practice, they function as an effective pre-stage that separates heavier and larger particles, while the finer fraction proceeds to the filter, significantly reducing its load and extending the life of the filtering medium. They are typically used with wood, biomass, recycling, TAP or abrasive dusts, where particle size separation and stabilisation of the entire extraction system are important.

Yes, cyclones can be used very effectively as pre-separators before the main filtration unit, and in practice this is one of their most common applications. They separate out coarse and heavier dust fractions at the inlet, significantly reducing the load on the filter, extending the life of the filtering medium, and stabilising the entire extraction system. With abrasive or heterogeneous dusts, this often also means lower pressure losses and reduced operating costs for the whole unit.

The main advantages of cyclones over conventional filtration lie in their ability to separate coarse dust fractions at the inlet, significantly reducing the overall load on the filter unit. This also protects filter hoses or cartridges from mechanical damage, particularly when handling abrasive materials. Another key benefit is reduced pressure drop and stabilised filter operation, as only fine particles enter the filter. The simplicity of the entire system is another major advantage: if a cyclone can function as a standalone solution, it represents the simplest and most robust form of extraction without requiring regeneration or complex control elements. In practice, this leads to lower capital and operating costs, along with highly reliable performance.

The disadvantages of cyclone separation mainly lie in the abrasive wear of the internal walls caused by particle rotation and impact. This is particularly relevant for highly abrasive dusts, which require protective lining using materials such as Hardox or other abrasion-resistant alloys. Another significant drawback is that a cyclone does not achieve 100% efficiency, especially regarding fine fractions that are not sufficiently separated by mass and escape with the air stream. Consequently, subsequent filtration is usually required in most applications to capture fine dust and ensure compliance with emission limits. Overall, while a cyclone is a robust and simple device, its main limitation lies in its effectiveness for fine separation.

Yes, we supply cyclones with Hardox lining, particularly for recycling plants and applications involving high abrasion where intense wear occurs on the separator walls. Typical sectors include crushing, sorting, biomass processing, or energy generation—such as large boiler houses—where long service life and minimal maintenance are essential. The Hardox lining significantly extends the cyclone’s lifespan and ensures stable operation even under extremely demanding conditions.

Hardox cyclone lining is suitable for all applications involving high abrasivity of dust or material, where intense mechanical wear occurs on the internal walls of the separator. Typical examples include recycling plants, crushing and sorting operations, processing of construction and municipal waste, biomass handling, as well as energy sectors such as large boiler houses with higher ash content and hard particles. It is also widely used in cement plants, lime kilns, steelmaking facilities, and other heavy-duty industrial environments where standard steel structures degrade rapidly. Hardox lining significantly extends the service life of cyclones while reducing maintenance costs and downtime.

Yes, cyclone separators can be thermally insulated or prepared for insulation directly during manufacturing. At our company, we handle this by leaving segmental cyclones uninsulated in the factory to avoid complicating transport and on-site assembly of individual components. Instead, we provide structural preparation for insulation, such as anchor studs or cladding attachment elements, allowing the customer or installation contractor to complete the final insulation after the cyclone has been assembled on site. This approach ensures both ease of transportation and optimal thermal insulation performance during operation.

Dust extraction from the cyclone is most commonly handled by a rotary feeder, which ensures smooth and sealed discharge of separated material into subsequent processes or containers. In practice, the design is selected according to the type of material: for wood and coarser fractions, rubber paddles are often used as they better accommodate potential jamming and reduce the risk of damage, whereas metal paddles are employed for exhaust gases and finer abrasive dusts to provide greater durability and thermal stability. Correct selection of the feeder is crucial for reliable material removal and trouble-free operation of the entire cyclone system.

In cyclone systems, a traditional discharge hopper is generally not used in the same way as with filters, because material removal is handled continuously. At the dust outlet, an expansion or quiescent chamber is most commonly employed to dampen the rotational motion of the dust stream from the cyclone and stabilise its flow before it enters the rotary feeder. This component also helps to fill the rotary feeder more evenly and reduces the risk of pulsating flow or overloading the discharge. Subsequently, the material falls through the rotary feeder into further processing equipment or a container, ensuring that the entire system operates smoothly without air back-suction.

Yes, we supply cyclones with rotary airlocks, which are standard components of the entire system, just like the dust outlet expansion vessel, steel support structure, or inspection doors for maintenance and servicing. The rotary airlock ensures a smooth and sealed discharge of separated material, allowing the cyclone to operate stably under varying operating conditions without risk of air backflow.

Typical pressure losses in cyclone separators range from approximately 800 to 1500 Pa, depending on the cyclone design, air flow rate, temperature and dust characteristics. For standard industrial applications, values typically fall between 1000 and 1200 Pa, as higher separation efficiency requires sufficiently intense swirling airflow. A well-designed cyclone always seeks a balance between separation performance and the energy consumption of the system fan.

Our cyclone separator design and sizing process begins with CFD analysis to define the basic optimal geometry for a given airflow rate and dust type. Based on these results, we determine key dimensions and operating parameters that ensure effective separation efficiency and pressure drop. These dimensions are then adjusted according to specific application requirements such as dust type, abrasiveness, temperature, space constraints, and connection method to the technology. The result is a structurally optimised cyclone combining calculated design with real-world operating conditions.

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Spare parts and upgrades for existing equipment

Yes, existing filtration equipment can typically be upgraded, provided that its basic structure and filter housing are in good technical condition following an inspection. Upgrades usually involve replacing or adding key components such as filter elements, the regeneration system, fans, or performance control and regulation systems. However, a technical assessment of the equipment’s condition is always required before any upgrades to determine what modifications are feasible and economically viable.

Modernisation is worthwhile when the filter housing is in good technical condition and its dimensions and design meet current operational requirements. In such cases, the main structure can be retained while key components—such as the filtration media, regeneration system, fan, or power control—are replaced or upgraded, significantly reducing investment costs compared to a complete equipment replacement. Modernisation is also beneficial when the aim is to reduce energy consumption, pressure drop, or implement demand-based control, provided that the supporting structure remains functional and free from major damage.

The suitability of a filtration system upgrade is most often determined by its operating costs and overall technical condition. A typical indicator is high energy consumption resulting from excessive pressure within the system and inefficient fan operation. Another key sign is the absence of power regulation or dampers, meaning the system runs at full capacity regardless of actual extraction requirements, significantly increasing running expenses. An upgrade is also advisable when filter elements frequently become clogged or have a short lifespan, as this suggests an unsuitable design or outdated technology. However, if the filter housing remains structurally sound, upgrading is often more cost-effective than replacing the entire unit.

Almost all key components of the filtration system that impact performance, energy consumption and operational reliability can be upgraded. The most common upgrades involve the control and regulation systems, enabling management based on actual demand, as well as the fan, where a variable frequency drive is often added to optimise performance. Filtration elements are another significant area, allowing for more efficient or lower-resistance media, while the regeneration system can be adjusted to reduce compressed air consumption and ensure more stable pressure drops. Overall, these modernisations aim to lower operating costs, improve efficiency and extend equipment lifespan.

Yes, filters from other manufacturers can be upgraded, as most industrial filtration systems operate on the same principle of separation and regeneration. However, a thorough technical inspection of the existing equipment is always required to assess the condition of the filter housing, fan, ductwork, and regeneration system, and to determine which modifications are technically feasible and economically viable. Based on this assessment, a specific scope for the upgrade will be proposed, such as replacing filter elements, adding control systems, or modifying the fan and control unit.

The main advantage of modernisation over purchasing new filtration equipment is the significant saving on capital expenditure, as it utilises the existing structure, which often constitutes the most expensive part of the entire system. Modernisation can achieve comparable improvements in performance, energy efficiency and reliability to those of a new unit, particularly when key components such as controls, fans, regeneration systems or filter media are replaced. Another benefit is the shorter implementation time and less disruption to operations, since complete dismantling and construction of a new system are avoided.

Filter plant upgrades typically involve a combination of partial dismantling of the existing technology and subsequent installation of new or modified components. Initially, a technical inspection and survey of the equipment are carried out to determine the scope of modifications. Selected parts, such as filter elements, regeneration sections, or original control systems, are then removed, followed by the installation of new modules which may include more efficient filtration media, flow adjustments, or optimised filter design.

The upgrade also includes installing a new control system that enables operation based on actual demand and process optimisation, often supplemented by regulating valves in the pipework for better performance distribution. Following installation, the system is commissioned, adjusted, and brought into service to ensure the upgraded plant delivers superior energy and operational performance compared to the original solution.

Modernising filtration equipment with thorough preparation typically takes only a few days, as most tasks can be planned and prepared in advance while the plant is offline. The key to minimising downtime lies in having a completed design, readily available components, and well-coordinated installation works. In practice, this involves first preparing the dismantling and assembly procedures, followed by partial replacement or integration of new sections, installation of controls and dampers, and finally commissioning and system tuning. Provided there are no on-site complications, modernisation can indeed be completed within a matter of days.

Production downtime during the filtration plant upgrade can be minimised primarily through thorough preparation and precise planning of the entire process. It is essential to have a completed technical design, all components ready, and clearly defined installation steps so that as much work as possible is carried out while the plant remains operational. The actual shutdown should be reserved only for essential tasks such as piping reconnection, electrical wiring, and final system commissioning. Effective coordination between the installation team and operations is also crucial to establish a precise schedule and minimise production downtime.

The performance of the existing filtration system can be enhanced in several ways, most commonly by replacing or upgrading the fan with a more powerful unit capable of handling higher air flow rates while maintaining appropriate pressure losses. Another option is to increase the filtering area by installing new filter elements or modifying the internal arrangement of the filter, thereby reducing surface loading and enabling higher throughput at the same or lower pressure drop. Performance can also be improved through optimisation of ductwork distribution and the addition of control systems that ensure more efficient use of available capacity during real-world operation.

The capacity of the filtration unit can be increased primarily by enlarging the filter area, as this reduces the surface loading on the filter and allows a greater volume of air to pass through at lower pressure loss. The second key step is increasing fan power, which must be capable of delivering higher airflow while maintaining the required vacuum within the system. In practice, both approaches are often combined—modifying or installing new filter elements alongside optimising or replacing the fan—to ensure the entire system operates stably and energy-efficiently without excessive pressure loss.

The existing extraction system can be expanded in several ways depending on its design and available capacity. For modular filters, expansion is typically achieved by adding an additional filtration module, which increases the filter area and reduces pressure drop at higher flow rates. At the same time, it is often necessary to assess and, if required, replace or supplement the fan so that it can handle the increased air volume while maintaining adequate negative pressure. Expansion also affects the pipework network, where dimensions, flow velocities must be verified and new branches or control dampers added as needed. However, it is always essential to check the overall hydraulic balance of the system to ensure that the expansion does not compromise energy efficiency or result in uneven extraction.

Yes, additional extraction points can be connected to the existing extraction system, provided that the system has sufficient power reserve and that both regulation and filtration capacity are correctly designed. In practice, new outlets are integrated by extending or modifying ductwork routes and adding control dampers, enabling the entire system to be balanced and ensuring uniform extraction across all points. However, it is always essential to verify whether the fan, filter, and ducting can handle the increased airflow without excessive pressure losses or a decline in efficiency.

The lifespan of the existing filtration system can be extended primarily through stable and controlled operation, where performance regulation ensures that the system does not run continuously under overload but only according to actual demand. This reduces pressure losses as well as wear on both the fan and filter elements. Proper sorbentation also plays a key role by capturing problematic dust components or gaseous substances before they enter the filter, thereby reducing its chemical and mechanical load. Combined with regular maintenance, regeneration checks, and monitoring of pressure loss, this significantly slows down system degradation and extends overall service life.

The most common reasons for modernising a filtration system include high pressure drop, which increases the fan’s electricity consumption and reduces overall system efficiency. Another frequent driver is excessive energy demand during operation, often caused by poorly designed control systems, undersized filters, or outdated automation. Modernisation is also carried out when there are frequent breakdowns, short service life of filter elements, a need to increase capacity, add extraction points, or reduce operating costs.

Yes, the control system of the filtration unit can be upgraded, and in practice this is very commonly done by replacing the original controller with a new, modern system. This allows for significant improvements in performance regulation, implementation of demand-based control, optimisation of filter regeneration, and reduction of energy and compressed air consumption. The upgrade typically also includes enhanced visualisation, remote monitoring, and improved fault diagnostics, which increase reliability and simplify maintenance of the entire unit.

Yes, a variable frequency drive can very often be added to an existing extraction system, provided the condition of the motor, fan and electrical installation is properly assessed. However, it is necessary to verify that the motor is suitable for speed control, correctly size the drive and ensure appropriate protections and system management. The installation itself enables smooth regulation of the fan output according to actual demand, leading to reduced electricity consumption, lower pressures within the system and overall more efficient operation.

Remote monitoring of the filtration unit can often be added to existing equipment in most cases, depending on the level of the original control system. If the unit is equipped with a modern PLC or open communication capabilities, monitoring can frequently be integrated relatively easily using modules for data collection, pressure drop measurement, fan status, and regeneration cycles.

However, if the equipment is older and lacks a suitable control system or data acquisition capability, it is often necessary to add or completely replace the control system, as remote monitoring without a data foundation serves little purpose. In practice, this means that simple systems are merely expanded, whereas older installations are frequently fully modernised to ensure reliable remote supervision and deliver genuinely actionable data.

Yes, filter regeneration can be significantly modernised; in practice, this is one of the most common upgrades for older equipment. Typically, the regeneration control unit is replaced or supplemented so that it no longer operates solely on a time basis but instead manages pulses based on the actual pressure drop across the filter. This results in much more stable operation, as regeneration responds to real-time fouling of the filter media and does not occur unnecessarily frequently or too late.

The modernisation may also include adding a differential pressure sensor, upgrading pulse valves, or optimising regeneration sequences, which leads to reduced compressed air consumption, a more stable pressure drop profile, and lower electrical energy consumption for the fan.

Yes, the energy efficiency of an existing extraction system can be significantly improved, and in practice, this is one of the most common modernisations. The greatest savings are achieved by optimising or replacing the fan, particularly if it operates outside its optimal working point or has low efficiency. A substantial impact is also delivered by adding or replacing the control system, which enables performance management according to actual demand, typically in combination with a variable frequency drive. Further significant savings result from improved extraction regulation, reduced pressure losses in the pipework, and optimised filter regeneration based on actual pressure drop. The combination of these modifications often leads to a marked reduction in electrical energy and compressed air consumption, as well as an improvement in overall operational stability.

Among the most frequently replaced spare parts for filtration systems are regeneration (pulse) valves, as they endure the highest mechanical and operational stress, with any failure immediately impacting filter performance. Filter media, such as bags or cartridges, are also regularly replaced due to gradual clogging, wear, or mechanical damage. Replacements of rotary feeder components, including blades or sealing elements, are common as these ensure continuous dust extraction while operating in abrasive conditions. Seals, compressed air hoses, and pressure sensors may also be replaced less frequently, depending on the specific equipment type and operating conditions.

Yes, we also supply spare parts for equipment from other manufacturers, as most components in filtration systems are standardised and compatible across various solutions. However, our primary focus is not merely the sale of parts, but ensuring the functional and reliable operation of the entire system; therefore, we provide spare parts primarily as part of service support or a technical solution to a specific issue.

The correct type of spare part can best be identified using the equipment’s manufacturing documentation, which lists component specifications, model designations and parameters. If this documentation is unavailable or incomplete, it is advisable to contact the manufacturer or a service organisation, who may identify the part based on photographs, the equipment label or by conducting an on-site inspection. In practice, both approaches are often combined—reviewing available documentation and verifying directly with the supplier—to ensure correct compatibility and functionality of the spare part.

For basic identification of spare parts, a photograph of the component and the serial number of the filtration unit are often sufficient, as these details allow you to trace the model type, configuration, and components used. However, in many cases, providing additional information—such as part dimensions, label markings, operating conditions, or year of manufacture—is helpful, as configurations may vary for older or modified equipment. The more precise the input data, the faster and more reliably the correct spare part can be identified.

Yes, we also supply filter hoses for equipment from other manufacturers, as most of these systems operate on similar design principles and can be technically adapted to fit specific dimensions and operating parameters. However, our primary focus is not the trade in spare parts but rather the design, optimisation, and ensuring the functional operation of the entire filtration system; therefore, we provide hoses and other components primarily as part of technical support and service.

Yes, we also supply filter cage housings for equipment from other manufacturers, as they are often produced in various standardised dimensions or can be adapted to specific filter types. We can supply or manufacture them to suit actual dimensions and operational requirements. However, our primary focus is not the supply of spare parts but rather the design and provision of complete functional filtration systems; therefore, we typically provide cages as part of technical support and service.

Yes, we also supply regeneration valves for older filtration equipment, as they typically feature standardised connection dimensions and can be replaced with more modern versions. Older valves can often be seamlessly swapped out for new ones, provided the connections, pressure ratings, and regeneration control system are compatible. In practice, this is a common way to upgrade entire pulse-jet cleaning systems, improving reliability, reducing compressed air consumption, and stabilising filter pressure drops.

Yes, we supply control units and complete control systems for filtration equipment, while also manufacturing electrical switchgear ourselves. This enables us to design, manufacture, and optimise the entire system as an integrated whole, including power regulation, regeneration management, and remote monitoring, ensuring greater reliability, improved energy efficiency, and easier maintenance.

Yes, we supply and manufacture rotary feeders and screw conveyors in various size ranges tailored to specific applications and operational requirements. We can adapt them both in terms of performance and design, including abrasion resistance or ATEX compliance. Thanks to our own manufacturing capabilities, we are able to provide an optimal solution that seamlessly integrates with your filtration system, ensuring reliable and trouble-free dust extraction.

Yes, we supply fans for existing filtration systems and always aim to verify the required pressure and performance first, ensuring that the new fan is correctly matched to the actual operating conditions of the system. The design includes checking pressure losses, the operating point, and overall energy balance, so that the replacement leads to improved efficiency and operational reliability.

Yes, the original fan can often be replaced with a more energy-efficient modern model, and this is a common upgrade in practice. Modern fans offer significantly higher efficiency, better-optimised impellers, and when correctly matched to the operating point, they deliver the same performance at lower electrical energy consumption. However, it is essential to re-evaluate system pressure losses and the actual required operating point to ensure the new fan operates within its optimal range and delivers the expected savings.

Yes, the performance of a filtration unit can often be enhanced without replacing the entire filter through several modernisation measures. Typically, this involves integrating additional filtration area to reduce surface loading, thereby enabling higher air flow rates at the same or lower pressure drop. Another option is optimising regeneration to improve cleaning of the filter media and prevent excessive clogging, which stabilises pressure conditions within the system. Significant impact can also be achieved through fan modernisation, including replacement with a more efficient model capable of operating effectively at the required duty point. Finally, performance can be improved by modifying or replacing the control system to enable more precise regulation based on actual demand and more efficient utilisation of the entire technology.

Yes, with cartridge filters it is generally not possible to switch to bag filters one by one, as the filter housing construction is designed differently in terms of space and mounting for cartridges and is too compact. In practice, this means that if a customer wishes to change technology from cartridges to bags, they usually have to replace the entire filter or its filtration section, including: the filter casing (or its internal assembly), the media mounting system, and often also the regeneration and air flow systems. Such a change is considered a complete modernisation or replacement of the filtration unit, rather than an element exchange.

No client has ever done this before because it would mean moving down several technical levels. Fabric filters commonly replace cartridge filters, but cartridge filters do not replace fabric ones. Cartridge filters are much more expensive in terms of consumables and have a short lifespan for the filter cartridges.

Yes, in most cases, filtration systems can be upgraded to meet new emission requirements. The most common approach is replacing the filter media with a more efficient type that offers higher filtration capacity and lower fine particle penetration. In addition to the media itself, the regeneration system is often modified to ensure stable cleaning and prevent pressure drop increases, or enhanced operational controls are added to maintain optimal filtration conditions. If the filter housing is in good condition, this represents a highly effective way to achieve new emission limits without replacing the entire technology.

Refurbishment of older filtration units typically involves a combination of dismantling worn components, thoroughly cleaning the entire internal filter space, and subsequently installing new filtering media. In practice, the equipment is first taken offline; old filter elements are removed, and the condition of support cages, seals, and seating surfaces is inspected. The filter chamber is then cleaned of dust and deposits, with any corrosion or build-up that could affect sealing integrity and airflow being removed as necessary. New filter hoses or cartridges are subsequently installed, their correct fitting and seal are verified, and the entire system is returned to operation, including checks on regeneration and pressure drop.

The most common issues with older filtration systems stem from the gradual wear of individual components and the resulting loss of original system efficiency. Typically, this involves the degradation of filter media, which becomes harder to regenerate, leading to increased pressure drops and reduced suction performance. Regeneration valves also frequently fail, no longer delivering correct pulses of compressed air, which results in uneven filter clogging. Another common problem is fan wear, particularly affecting bearings and rotor balancing, manifesting as vibrations, noise, and lower efficiency. Older units are also prone to leaks in ductwork and discharge points, further compromising system stability and increasing operational costs.

Investing in a new filtration system is economically justified when the existing system can no longer meet performance requirements even after modernisation, or when necessary upgrades are technically and financially comparable to a new investment. This typically applies where significantly higher extraction capacity, substantially lower pressure losses, compliance with stricter emission limits, or changes in manufacturing technology are required. A new filter also makes sense when the current equipment is nearing the end of its service life, has worn structural components, or incurs disproportionately high operating costs (energy, maintenance, breakdowns) over the long term.

The return on investment for upgrading filtration equipment depends primarily on system size and operating modes. However, by modernising the control system, adding dampers, and implementing performance regulation, significant savings in both electricity and compressed air can often be achieved. In practice, this means that fans no longer run continuously at full capacity; instead, extraction occurs only where genuinely required, substantially reducing operational costs. For most industrial applications, payback periods typically range from one to two years, depending on the number of extraction points, operating hours, and energy prices.

The service life of the filtration unit can be extended by 10 to 20 years primarily through systematic servicing, regular maintenance, and timely minor repairs that prevent the gradual degradation of individual system components. Continuous corrosion treatment and structural protection are also crucial, as the condition of the filter housing and load-bearing parts often determines whether it is worthwhile to modernise or replace the equipment. Regular replacement of wear-and-tear parts, such as filter media, regeneration valves, seals, or fan bearings, along with correct operational settings to prevent continuous overload, also has a significant impact. If these measures are consistently adhered to over the long term, even an older filtration unit can operate reliably for considerably longer than its standard service life.

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Service and maintenance

Maintenance of filtration equipment typically comprises ongoing operational checks and regular professional servicing. In practice, operators should carry out periodic visual inspections, including monitoring for leaks, assessing the condition of key components, and regularly recording pressure drop, as its trend best indicates filter status. Additionally, it is recommended to have a qualified supplier or service provider conduct an annual detailed inspection covering regeneration processes, filter elements, fans, safety features, and the overall technical condition of the equipment.

Regular maintenance is required for all key components of the filtration unit, as they directly impact its performance, safety and energy consumption. The condition of the filter elements, their degree of fouling and regeneration are critical, as these factors determine pressure losses. It is also essential to monitor the fan, particularly regarding vibrations, bearings and balancing, alongside electrical installations including regular inspections. For ATEX equipment, earthing and explosion protection components must additionally be checked. Inspection of ductwork, dampers and discharge points should not be overlooked, as leaks or malfunctions can significantly increase operating costs.

Filtration equipment typically requires servicing when operators begin to notice changes in operation, most commonly a drop in suction performance or a decline in extraction quality. Typical indicators also include an increase in pressure loss, more frequent regeneration cycles, higher fan energy consumption, or uneven system operation. Other warning signs are fan vibrations, ductwork leaks, or issues with hopper emptying. In practice, therefore, servicing is driven not merely by time but primarily by changes in system behaviour, which operators identify through performance and operational stability.

The most common issues with filtration systems involve faults in the regeneration system, particularly malfunctions of pulse valves or the control unit, which result in either insufficient or excessive cleaning of the filter media. Another frequent problem is damage to or blockage of filter elements (cartridges), leading to a rapid increase in pressure drop and reduced suction performance. Additionally, fan failures often occur, including bearing wear, imbalance, or electric motor faults, alongside operational issues such as blocked discharge chutes or leaks that impair overall system efficiency.

The most common causes of reduced suction performance are primarily increased filter pressure drop, resulting from the clogging or blinding of the filtering media and the accumulation of a dust cake, which significantly increases air flow resistance. Other frequent causes include leaks or blockages in the ductwork, fan faults (such as bearing wear or reduced speed), ineffective filter regeneration, and improper system control where the airflow is not adjusted to meet current demand.

A clogged filter is primarily identified by reduced suction power and the system failing to draw air as intended, even when the fan is running. The most typical and reliable indicator is high pressure loss shown on the manometer or in the filter control system, which rises over time and does not respond correctly to regeneration. In practice, this often manifests as uneven suction at workstations, increased fan noise, and overall poorer system stability.

Damaged filter hoses are most commonly identified by increased dust emissions at the outlet, often referred to as “chimney dusting” or blow-off, because the filter can no longer capture fine particles. Another typical sign is uneven fouling or a “full” blow-off sleeve, where certain hoses lose their function and dust passes directly through the damaged area (e.g., cracks, holes, or loose connections). In practice, this often manifests as localised reductions in pressure drop, poorer regeneration, and the filter failing to maintain stable performance despite correct cleaning settings.

Leakage in the filtration system is most often identified when the fan is switched off and during the regeneration run-down. During compressed air pulses, dust escapes from leak points—typically at joints, flanges, discharge outlets, or around filter chambers. Other signs include visible dust leaks during regeneration, localised dust deposition around the filter structure, or persistently high dust levels in the vicinity of the equipment, even though the system should be sealed. In practice, leaks often do not manifest during normal operation but rather during pulse regeneration, when a short-term overpressure occurs inside the filter.

Dust leakage from the filtration unit is primarily identified by fine dust appearing where it should not normally be found – typically around the exhaust, on the filter frame, or in the hall near the equipment, even when the system is operating correctly. Another sign is a deterioration in air quality within an area that should contain clean air post-filtration, or visible haze of fine dust during operation or regeneration. In practice, this often manifests as localised contamination despite correct pressure drop and fan performance, which usually indicates a leak, damaged filter media, or issues with the seals on hoppers or joints.

The most common causes of high pressure drop include the clogging or blinding of the filter medium, which leads to a gradual blockage of pores, particularly in tubular (bag) filters. Other factors are ineffective or insufficient regeneration, where the dust cake is not removed adequately, as well as issues with the compressed air used for regeneration—such as low pressure, poor air quality, or leaks in the distribution system—which reduce cleaning efficiency. An unsuitable operating regime also plays a significant role, where the filter operates under long-term overload or outside its design conditions.

The most common causes of low suction performance are primarily high pressure loss in the filters or filter bags, which significantly increases flow resistance and restricts air volume through the system. Another frequent cause is poor or missing regulation, where the system does not operate according to actual demand or the fan’s operating point is incorrectly set. Performance can also be reduced by partial blockages in the ductwork, system leaks, fan faults, or insufficient air supply from individual extraction points.

The most common causes of frequent filter clogging are primarily unsuitable design of the filtration equipment, where the filtering area is too small or the airflow distribution is incorrect. This leads to high surface loading and rapid formation of a dust cake. Furthermore, clogging is significantly influenced by an inappropriate choice of filter media for the specific type of dust, unsuitable operating conditions (e.g., high humidity, sticky or fine dust), inadequate or ineffective regeneration, and unstable operational regimes involving frequent changes in flow rates and pressure ratios within the system.

The most common causes of poor filter regeneration include insufficient or unstable compressed air pressure, blocked or damaged pulse valves, incorrectly set regeneration control cycles, and low-quality compressed air with high moisture content or contaminants, which reduces the cleaning efficiency of the filter media. The result of inadequate regeneration is gradual filter clogging, increased pressure drop, and consequently higher electrical energy consumption by the fan, as the system must continuously overcome greater flow resistance.

The correct operation of filter regeneration can be verified primarily by monitoring pressure drop over time. Before the fan is switched off, the pressure drop should be higher, corresponding to the filter loading during operation. However, after switching off the fan and allowing the post-cleaning process to complete, the pressure drop should gradually decrease to a lower stable value, indicating that regeneration has effectively removed the dust cake from the filter media.

If the pressure drop does not decrease or decreases only minimally following regeneration, this usually indicates an issue with the regeneration process – such as insufficient compressed air pressure, faulty pulse valves, or clogged filter media. Conversely, a pressure drop that is too low or “fluctuating” may indicate leaks or damage to the filter elements.

For the regeneration of filtration equipment, compressed air at approximately 6 bar is most commonly used. This is the standard pressure for most industrial filters and ensures effective dust removal from the filter media. For smaller or less demanding systems, the operating pressure may be lower, typically around 4 bar, provided that the design of the filter and pulse valves allows it. However, effective regeneration depends not only on the pressure setting but also on pressure stability, air quality (dry and clean), and the correct adjustment of pulse duration and frequency. These factors are critical in determining actual regeneration efficiency.

The quality of compressed air has a fundamental impact on the operation of filtration equipment, as it directly affects regeneration efficiency. If the air is not sufficiently dried, water condensation occurs in the pipework and pulse valves, which can lead to blockages, corrosion, or functional failures. In outdoor installations, winter operation is particularly critical; if drying is inadequate (for example, resulting in a pressure dew point worse than -40 °C), condensate may freeze. This causes regeneration failure, a rapid increase in pressure drop, and reduced suction performance. In addition to moisture levels, air purity free from oil and contaminants is essential, as these shorten valve lifespan and compromise the reliability of the entire system. Consequently, this leads to higher energy consumption and increased operating costs.

Regeneration valves should be inspected regularly at least once a year, ideally as part of a service check carried out by the supplier or a specialist service provider. This is because they are a key element affecting filter cleaning efficiency, pressure losses and compressed air consumption. During inspection, valve tightness, response time, correct diaphragm function and any wear that could cause insufficient or uneven regeneration of the filter media are monitored.

It is advisable to check the compressed air collectors at least once a year, ideally as part of regular maintenance carried out by the supplier or a professional service company. This is because they are a key component of the regeneration system, influencing pressure stability and the correct operation of pulse cleaning. During inspection, the system’s integrity, the condition of valves and connections, the functionality of safety components, and the overall technical state are typically assessed to ensure a safe and reliable supply of compressed air for filter regeneration.

During operation, it is advisable to carry out regular visual inspections of the equipment, paying particular attention to sealing integrity, dust leaks, and the general condition of filters, pipework, and discharge points. It is also important to monitor operational signs – if anything whines, squeaks or hisses, this should always be treated as an immediate signal for inspection, as these noises often indicate the onset of a fan fault, leakage or regeneration issues. Such phenomena should not be ignored or overlooked but addressed as soon as possible, since timely intervention significantly reduces the risk of breakdown and system downtime.

Among the most critical spare parts to keep in stock are those essential for regeneration and the continuous operation of the filter. Typically, these include replacement pulse (regeneration) valves, as a failure immediately affects the cleaning function of the filter media and leads to increased pressure drop. It is also advisable to maintain stocks of rotary valve components, such as blades or sealing elements, which ensure proper dust discharge, as well as basic filter media (hoses, cartridges), since damage or blockage directly impacts suction performance. Overall, the parts that should be kept in stock are primarily those whose absence would cause an immediate shutdown or significant operational restriction.

Production downtime can be minimised primarily through systematic preventive maintenance, where equipment is regularly inspected and serviced before faults occur. Crucially, annual preventive servicing by the supplier is essential to identify wear on regeneration valves, assess the condition of filter elements, fans, and other critical components, and allow for planned replacements rather than emergency interventions. It is also important to continuously monitor operating parameters, particularly pressure drops, and respond promptly to deviations, as timely diagnosis and part replacement significantly reduce the risk of unplanned downtime and ensure stable operation of the entire technology.

The lifespan of the filtration unit can be extended primarily through regular maintenance and correct performance regulation, as this maintains stable operating conditions and minimises both mechanical and energy-related stress on the system. It is also important to monitor pressure drop, replace filter elements in a timely manner, ensure proper regeneration function, and eliminate operation in overloaded modes. If the system is controlled according to actual demand rather than running continuously at maximum output, wear on the fan, filter, and ductwork is significantly reduced, thereby extending its overall service life. Another key factor is correct sorption, which helps protect filtration media from blinding, reduces chemical loading on the system, and further limits filter degradation in demanding applications.

A general overhaul of the filtration unit involves a complete renewal of key wear-and-tear components to restore the system to near-original technical condition and reinstate its performance and reliability. This typically includes replacing filter elements (hoses, cartridges), inspecting and replacing seals, guide rails, and other seating components, reconditioning or replacing fan bearings, servicing regeneration valves, and optionally checking the drive mechanism and electrical components. The overhaul also encompasses a thorough mechanical inspection of the structure, removal of deposits and corrosion, adjustment of the regeneration system, and subsequent testing of operational parameters—particularly pressure drop and suction performance—to ensure the equipment is fully operational and stable.

Modernisation is cost-effective when the mechanical part of the filtration unit, particularly the filter housing, remains in good technical condition and does not require complete replacement. In such cases, key components can be replaced or upgraded—such as filter elements, regeneration systems, fans, control systems, or power regulation—which enables significant improvements in energy efficiency, reduced pressure losses, and extended equipment lifespan at substantially lower investment costs compared to purchasing a new unit. Modernisation is typically also worthwhile when the aim is to reduce operating expenses, implement demand-based regulation, or add air recirculation, provided that the filter structure remains sound without major corrosion or damage.

Yes, filtration equipment from other manufacturers can often be upgraded, as most industrial filtration systems operate on the same principles of separation, regeneration, and air extraction. In practice, the existing filter housing is usually retained if it is in good technical condition, while key components such as filter media, the regeneration system, fan, or control and regulation system are replaced or supplemented. However, it is always important to assess the specific design and operating conditions, as compatibility and upgrade possibilities may vary depending on the equipment type, age, and technical state.

Filter bag replacement typically involves several steps, with the aim of safely removing damaged or clogged bags and replacing them with new ones without damaging the support cage or sealing elements.

Firstly, the equipment is shut down and secured against accidental start-up; ideally, a regeneration cycle is allowed to complete and the system depressurised. The pulse jets are then removed to provide access to the individual filter bags. Next, the fasteners – usually screws or clamping mechanisms – are loosened, and the bag is taken off the support cage. After inspecting the cage and seating surfaces, a new filter bag is fitted, correctly seated on the seal, and secured. Finally, everything is reassembled, the pulse jets are refitted, and a leak test and regeneration function check are carried out.

The downtime for filter plant maintenance depends on its size, design, and the extent of the intervention. For smaller and medium-sized filters, it typically lasts several hours, as this usually involves replacing filter elements, checking regeneration processes, and carrying out basic servicing tasks. In the case of large filter banks or complex systems with multiple sections, extensive regeneration, and dust handling, downtime can extend to several days, particularly if a major overhaul or replacement of significant components is required. The key factors are always preparation, availability of spare parts, and efficient service organisation, which can significantly reduce downtime.

Preparing equipment for planned maintenance is essential to reduce downtime and minimise production losses. The foundation of this process lies in the timely preparation of spare parts, ensuring that all consumable components—such as filter media, seals, strips, or valve parts—are readily available. It is also advisable to stabilise the equipment operationally beforehand, monitor pressure drops, and identify any issues that need addressing during the service. Prior to shutdown, it is crucial to ensure safe isolation of the technology, depressurisation, electrical lockout, and access to all maintenance points. Thorough preparation significantly reduces intervention time and lowers the risk of unplanned complications during servicing.

Preventive inspections can identify a range of issues before they cause equipment failure or downtime. The most common problems are wear and tear or malfunctioning regeneration valves, which manifest as reduced filter cleaning efficiency. Additionally, increased fan vibrations can be detected early on; these typically indicate bearing issues or rotor imbalance. A critical warning sign is dust leakage on the clean side of the filter, suggesting damage to the filtering media, leaks, or improper seating of the elements. Preventive checks also involve monitoring pressure drop and overall system behaviour, enabling the timely detection of gradually developing faults.

Remote diagnostics of filtration systems operate by monitoring key operational parameters online, such as pressure drop, regeneration status, compressed air pressure, fan operation, and system alarm states. This data is transmitted to a remote supervision system where it can be evaluated in real time. If deviations from normal operation occur—for instance, a rapid increase in pressure drop, reduced performance, or regeneration errors—the system alerts the operator or maintenance team, enabling timely intervention before a breakdown occurs. The objective is therefore early problem detection, minimisation of downtime, and optimisation of operations without the need for physical on-site inspection.

During operation, it is advisable to monitor several key parameters that enable the early detection of changes in filter system behaviour and help prevent breakdowns. The most critical factor is the pressure drop across the filter, as this best indicates the degree of clogging and regeneration efficiency. It is also recommended to monitor fan performance or vacuum levels within the system, regeneration status (including pulse valve function and compressed air pressure), energy consumption, and any alarm states from the control system. In more advanced installations, compressed air quality, flue gas temperature, and operating hours for individual components are also monitored.

Typical signs of an impending filter system failure include changes in its normal behaviour, which operators often notice first. These are particularly unusual noises, such as whistling, rumbling, or knocking, which may indicate issues with the fan, bearings, or regeneration process. Another common symptom is dust leakage on the clean side of the filter, pointing to damage to the filter media or leaks. A significant warning sign is also a drop or, conversely, instability in suction performance, fluctuations in pressure loss, more frequent system alarms, or the need for more frequent regeneration. These symptoms usually indicate that the equipment is still running but operating outside optimal conditions, and failure is only a matter of time.

Unplanned shutdowns of filtration units are best prevented by combining preventive maintenance with continuous monitoring of key operational parameters, particularly pressure drop, which is the most reliable indicator of filter clogging or regeneration issues. It is also essential to regularly check fan function, regeneration performance, system integrity, and the condition of filter elements in order to detect emerging faults early. When deviations are identified promptly and addressed through planned actions, the risk of sudden failures that lead to production downtime is significantly reduced.

Preventive maintenance is crucial as it enables the detection of wear and emerging faults before they lead to breakdowns, significantly reducing unplanned production downtime. Through regular inspections, servicing, and monitoring of operating parameters—particularly pressure losses—equipment can be maintained in optimal condition, ensuring stable and reliable operation. In practice, this means fewer failures, lower repair costs, and higher overall equipment availability.

Preventive maintenance of filtration equipment should be carried out at two levels – continuously during operation and regularly within scheduled professional intervals. In practice, in-house staff should carry out random visual and auditory checks during normal operations, monitoring the basic condition of the equipment, leaks, vibrations or unusual noises. It is also recommended to have a systematic preventive service inspection conducted by the supplier or a specialised maintenance provider, typically once a year, which includes a detailed check of regeneration, the fan, filter elements, electrical components and the overall technical condition of the equipment. This combination enables problems to be identified early on and minimises the risk of unplanned downtime.

The primary advantage of the service contract is that it transfers responsibility for planning and organising maintenance to the supplier. This ensures regular inspections, adherence to agreed schedules, and the provision of necessary spare parts on-site, thereby minimising the risk of delays and unplanned downtime. For operators, this means they no longer need to actively manage service schedules, spare parts storage, or coordinate interventions. They can instead focus on production while their equipment is maintained in optimal technical condition, significantly reducing the risk of breakdowns.

Maintenance costs for filtration equipment can be reduced through a combination of appropriate technology selection and operational optimisation. Significant savings are achieved, for example, by replacing cartridge filters with fabric (bag) filters, which typically offer a longer service life, lower sensitivity to clogging, and often lower pressure drops. This not only reduces the frequency of replacements but also decreases fan energy consumption. Further cost reductions can be realised through correctly set performance regulation, effective filter regeneration, and preventive maintenance, which enables timely replacement of worn components and prevents breakdowns. Overall, a well-designed and controlled system incurs significantly lower maintenance costs than an undersized or poorly regulated solution.

Service intervals can be extended primarily by reducing the operational load on the filtration system and stabilising its performance. The correct choice of filtration technology plays a key role—for example, replacing cartridge filters with fabric (bag) filters, which offer significantly longer service lives and require less frequent intervention. Additionally, quality and controlled regeneration, stable compressed air supply, and output regulation according to actual demand help reduce clogging and mechanical stress on the system. The result is extended operational intervals between services, reduced component wear, and overall more stable equipment performance.

Long-term reliable operation of the filtration system is ensured by combining correct local maintenance with regular professional service interventions from the supplier. In practice, this means that operators carry out ongoing visual and operational checks, monitoring pressure drops, regeneration status, system integrity, and basic functional performance, while the supplier provides regular service inspections—typically once a year—to check key components, adjust the system, and replace worn parts. This combination of preventive maintenance and professional servicing significantly reduces the risk of breakdowns and unplanned downtime, ensuring stable and efficient operation throughout the equipment’s lifespan.

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Faults and their resolution

The extraction system has low performance. Check the frequency on the variable speed drive to ensure it is not reduced and that the fan is not running below 100%, as in such cases, the performance can simply be increased. Also check the pressure drop across the filter, because excessive increase can significantly restrict airflow and reduce overall system performance. Furthermore, verify the pressure drop of the return filter sleeve if air recirculation into the hall is used, as its clogging may also limit performance. Finally, check the position of the control dampers in the ducting to ensure they are fully open rather than partially closed, which can cause flow restriction and uneven distribution of performance throughout the system.

If the vacuum level in the system drops, this usually indicates either an increase in pressure loss within a section of the technology or that the fan is reducing its speed due to control adjustments, thereby lowering overall extraction performance. In the first step, it is necessary to check for pressure losses across filter pockets or sleeves, as their clogging is the most common cause of a gradual decline in vacuum. Subsequently, you should verify the settings of the fan’s variable frequency drive to ensure that there has been no reduction in speed or shift in the system’s operating point that would restrict available performance.

If the fan fails to maintain performance, this usually indicates an increase in system pressure loss or that the fan has started reducing its speed due to control adjustments. A common cause is incorrect negative pressure regulation, where the sensor measures the value on the clean side of the filter rather than the dirty side of the system. In such cases, the controller does not detect the actual pressure drop across the filter, leading to improper fan performance management. It is therefore essential to check the position of the negative pressure sensing point and, if necessary, swap the pressure tubes, as accurate measurement must always be taken on the dirty side of the filtration system to ensure the control system accounts for the true resistance of the filter.

The ducting is blocked. What should you do? It must first be cleaned mechanically or operationally, and then the root cause of the blockage should always be identified. The most common cause is insufficient transport velocity within the ductwork, which leads to deposits building up gradually until the cross-section becomes completely obstructed. The solution is to flush the ducting with the control dampers open and the fan running at 100% capacity, thereby dislodging accumulated material. Subsequently, the system must be readjusted to ensure a correct transport velocity of approximately 20 m/s throughout the entire run, preventing recurrent deposition.

The system is experiencing fluctuating suction. What can be done about it? If the system shows fluctuations in suction, this may indicate that the PID control of the frequency converter is poorly tuned and unable to consistently compensate for pressure changes within the network. Another common cause is sudden changes in vacuum caused by opening or closing other control dampers in the system, which disrupts the balance of the entire extraction process. It is therefore necessary to check the settings of the frequency converter’s regulation, verify the correct operation of the PID loop, and assess the system’s response to changes in individual damper positions to ensure stable and smooth suction.

Suction is unstable. What can be done about this? If suction is unstable, the issue must be clarified based on how the instability manifests, as it could involve pressure fluctuations over time, competition between branches, or rapid changes in fan performance when damper positions change. The most common cause is poorly tuned PID regulation on the variable frequency drive, which fails to respond adequately to dynamic system changes, or incorrectly set control dampers that cause sudden flow variations when switching between individual branches. Additionally, it may be a hydraulically unbalanced system where some branches have significantly higher or lower pressure losses, leading to power redistribution among sources. It is therefore necessary first to determine whether the issue involves fan fluctuation or distribution instability within the pipework network, and then adjust the regulation or system balancing accordingly.

Firstly, it is essential to check the compressed air pressure, which should be approximately 6–7 bar, as low pressure can cause ineffective or weak filter regeneration. It is also necessary to verify whether regeneration pulses are audible and whether the regeneration control unit is active (checking the display and any alarms). A very effective diagnostic step is comparing the pressure drop before switching off the fan and after performing an offline regeneration followed by restarting the system. If the pressure drop does not decrease at all or only minimally, this is a typical sign of a blocked or degraded filter medium, necessitating its replacement.

If the ducting is blocked by dust, the most common cause is low transport velocity, which prevents material from being carried away and leads to gradual accumulation within the ducts. The solution is to clean the ducting and subsequently flush the system operationally with all dampers fully open and the fan running at maximum capacity, ensuring that accumulated deposits are removed. Afterward, it is necessary to correctly re-regulate the system so that adequate transport velocity is maintained throughout the entire route, preventing further dust deposition.

If material accumulates in the bends of the pipework, the most common cause is low transport velocity. At this speed, the flow lacks sufficient energy to keep particles suspended, leading to their gradual deposition at points where the direction changes. The solution is to increase the flow velocity within the system, adjust the pipe dimensions if necessary, or optimise the route to reduce the number of critical bends. Subsequently, the system should be flushed operationally at full capacity with dampers fully open to remove deposits and restore stable material transport.

This phenomenon can typically occur when the extraction system is switched off or during offline regeneration, as regeneration pulses are transmitted back into the suction duct. In such cases, a non-return valve must be installed to prevent backflow into the distribution network. However, if reverse flow occurs during operation, this indicates an abnormal condition usually associated with connecting multiple filtration systems to a single common exhaust. In this configuration, differing pressure losses in the chimney flue can cause one system to overpower another, resulting in backflow. To resolve this, the system must be hydraulically balanced or supplemented with non-return valves or separated exhaust branches.

In such cases, it is necessary to contact the designer or supplier of the duct system and address the situation through a complaint or a technical recalculation of the design. The system must be recalculated for real operating conditions, particularly with regard to maintaining the required constant transport velocity throughout the entire route. If the velocity is not correctly designed, dust deposition occurs, leading to gradual blockage of the ducts and, in extreme cases, an increased risk of fire—for example, if a spark settles on accumulated material deposits. A correct design must always eliminate these risks during the sizing phase.

If the conveying speed was previously satisfactory but has now decreased, it is essential to first identify the cause of increased pressure loss in the system. Additionally, check the fan frequency settings to ensure that a reduction in RPM due to regulation or a change in operating point has not occurred. In practice, users often add extra extraction points to the system without recalculating the total capacity, leading to reduced speed in existing branches and subsequent material deposition within the ductwork. In such cases, the system must be hydraulically balanced again, and the control settings adjusted to ensure the required conveying speed is maintained throughout the entire route.

If the air velocity in the ductwork does not match the original design immediately after commissioning, this constitutes grounds for a complaint to the supplier, as the system was either incorrectly designed or commissioned. If the issue arises only after a period of operation, it is necessary to investigate an increase in pressure loss, such as due to filter blockage, changes in operating conditions, or incorrect fan regulation. A very common cause is also the addition of another extraction point to the system that was not included in the original design; this leads to reduced velocity in individual branches and overall system imbalance. In such cases, a new balancing procedure and recalculation of the entire network are required.

Exceeding the transport velocity in pipelines is generally not a critical issue regarding blockages, but it can lead to increased wear on pipes, bends, and other components due to the abrasive action of the flowing material. If the speed is significantly higher than the design specification, it is advisable to adjust it by reducing the fan speed using a variable frequency drive, or alternatively, by regulating the system via dampers so that the operating point shifts into the optimal range. The aim is always to strike a balance between adequate material transport and an acceptable level of equipment wear.

In such cases, it is essential to pinpoint exactly where the pressure drop occurs, as the underlying causes differ significantly depending on the system component in question – whether it be the suction piping, filter unit, exhaust ducting, or the filter bags themselves. Each section has its own typical resistance mechanism and a distinct method for resolving the issue. In the suction line, clogging or low transport velocity are common culprits; within the filter, the problem typically stems from an overloaded or poorly regenerated filter medium; in the exhaust, it may be due to flow restriction; and with the bags themselves, blockage or degradation is often to blame. Therefore, accurate diagnosis of the pressure drop location is crucial for effectively resolving the issue.

In such cases, it is essential to first rectify all leaks and restore the system’s full integrity to prevent the suction of false air, which significantly reduces extraction efficiency and disrupts the balance of the entire system. Subsequently, it is advisable to investigate the cause of the leaks; this is often due to long-term increased transport velocity causing erosive wear on pipes, bends, or joints, or alternatively, mechanical damage or poorly executed connections. After resolving the fault, the system’s balance and operating conditions must be rechecked to prevent recurrent pipe damage.

If the airflow is uneven, this most often indicates that multiple extraction points are connected to the system, resulting in hydraulic imbalance. The machines closest to the source experience a higher proportion of suction pressure, while those further away or at the end of the line are undersized and do not draw sufficiently.

This condition is common in unbalanced systems, as total suction decreases with each additional open point, causing airflow to redistribute according to the path of least resistance. The solution lies in properly balancing the system by progressively throttling individual branches, typically starting with those nearest to the fan. This redirects air volume towards more distant machines and ensures that the required suction performance is achieved at the final extraction point.

Turbulence in pipelines is a common phenomenon, particularly at bends, branch points and changes in flow direction. It is not necessarily problematic on its own unless it leads to subsequent adverse effects such as local material deposition or erosive damage to the pipe walls. However, if turbulence causes leakage or excessive wear of the pipeline walls, it is necessary to modify the route, specifically by optimising the pipeline layout and replacing sharp directional changes with smoother geometries. In practice, bends and branches with larger radii are most commonly used, as they ensure calmer flow and reduce mechanical stress on the system.

If the pipeline route is not optimal, this may indicate either unsuitable spatial routing of the pipework or an uneven distribution of suction performance across the system. In practice, however, a perfectly optimal route often does not exist, as the pipework must accommodate real-world construction and technological constraints, such as brackets, cranes, machinery, or other obstructions within the hall. It is therefore essential to always seek a compromise between ideal aerodynamics and actual installation possibilities, subsequently commissioning the system correctly so that even a less-than-ideal route operates stably in service.

In essence, there are two primary causes. Either pressure loss is increasing somewhere within the system—for instance, due to blockage of the filter media, pipework, or associated components—which requires locating and rectifying the issue. Alternatively, fan regulation may be reducing speed, such as through PID control responding to negative pressure, leading to a decline in overall extraction performance. In both scenarios, it is necessary to inspect both the system’s pressure losses and the configuration and behaviour of the fan controller.

If the filter is so heavily loaded that material has been forced between the filter media layers and formed an irreversible deposit, regeneration alone will typically not resolve this condition. In such cases, mechanical cleaning or replacement of the filter media is required, as the filter structure has suffered permanent fouling.

Subsequently, it is necessary to identify the root cause of this issue – most commonly, this stems from unsuitable operating conditions, incorrect regeneration settings, or an inappropriate pre-separation type. As a preventive measure, you can add a pre-separation stage, such as a cyclone, rotary separator, or pre-chamber, which will reduce the load on the filter by removing coarse fractions and lowering the risk of recurring blockages.

This condition typically manifests as a gradual increase in pressure drop because the filter medium is not being effectively cleaned. The first step is to check the regeneration function—specifically, whether all pulse valves are operating correctly and if the regeneration unit is properly controlled. It is also advisable to listen to the system’s operation to ensure that pulses are audible and regular; their absence or weakening often indicates a fault with the valves or control system.

At the same time, it is necessary to verify the compressed air pressure in the system, as low pressure (typically below the required value of approximately 6–7 bar) can cause insufficient cleaning of the filter medium. If the issue persists after basic checks, service support should be contacted to perform a detailed diagnosis of the pulse system and control unit.

This is a normal operational state to a basic extent, as the pressure drop initially rises rapidly before stabilising at nominal values. During standard operation, it then gradually increases depending on the loading of the filter area and the type of dust, and is periodically reduced in steps during offline regeneration when the fan is switched off and an intensive cleaning of the filter elements takes place. The overall profile of the pressure drop typically exhibits a sawtooth pattern, where gradual increases alternate with sharp drops following regeneration. However, if the pressure drop rises beyond the scope of the normal cycle, it is necessary to investigate causes such as insufficient regeneration, system overload, or unsuitable operating conditions. Check and compare the pressure drop before and after regeneration with the fan switched off.

If the filter continues to clog despite standard regeneration, the most common cause is not the intensity of the pulses themselves, but rather the nature of the dust—specifically the presence of fats, oil aerosols, or condensable components that form a permanent sticky film on the filter media. This film cannot be removed by standard pulse cleaning, as it leads to the “plugging” of the filter fabric structure.

In such cases, it is necessary first to identify the source of the contamination (e.g., machining processes, oil vapours, emulsions, or process fumes) and subsequently adjust the process. A typical solution involves adding sorption upstream of the filter, or a pre-separation stage (such as a cyclone or separator), which reduces the load on the filter by removing heavy and sticky components. If the media is already contaminated, replacing the filter bags is often required, as the degradation is irreversible.

This condition is normal operational behaviour for multi-chamber filtration units in most cases and does not indicate a fault on its own. If one chamber is currently drawing more flow, the local pressure drop within it increases, which naturally leads to a redistribution of the flow, causing the second chamber to become more loaded; thus, the system dynamically balances itself.

Similarly, the situation where a larger amount of coarse fraction accumulates under one chamber compared to another is not critical, as coarse particles typically settle faster and the fine fraction distributes more evenly over time. Therefore, uneven loading of the chambers does not signify a malfunction but rather normal hydraulic adaptation of the system to current operating conditions.

In such cases, the filter medium must be replaced immediately, as damage allows dust to penetrate into the clean side of the system. This can subsequently lead to increased fan wear, blockage of the exhaust ducting, and an overall reduction in extraction efficiency.

If this fault is ignored, secondary issues may arise throughout the entire system. Therefore, it is essential to replace the filter elements as soon as possible and then investigate the cause of the damage to prevent recurrence.

This condition is one of the most reliable indicators of damage or degradation to the filter media, as it signifies a breakdown in the filter’s separation function and allows dust to penetrate into the clean section of the system. In such cases, the filter elements must be replaced immediately, as continued operation may lead to secondary issues, such as fan blockage, exhaust duct obstruction, or deterioration of the extracted air quality. It is also advisable to investigate the cause of the damage to prevent recurrence during operation.

This condition is highly critical, as condensation within the filter unit leads to fouling of the filter media, corrosion, and a significant increase in pressure drop. If this is a new phenomenon that was not previously present, it is highly likely that a new source has been connected to the system, increasing the moisture content of the flue gas or air stream. In such cases, it is essential to identify this source and assess its impact on the system, temporarily disconnecting it if necessary to verify the cause. Simultaneously, the thermal regime of the filter and piping must be checked, and thermal insulation and heating of critical components should be added where required to prevent temperatures from falling below the dew point and further condensation occurring.

In practice, this is rarely an issue in most cases when extracting air or exhaust gases with similar humidity and temperature to the surrounding environment, as there is no significant cooling below the dew point. The problem arises when there is higher humidity or a content of condensable components in the airstream—typically with gas burners, steam processes, or wet technological evaporation. In such cases, cooling occurs within the uninsulated filter, leading to condensation and subsequent clogging of the filter media, along with deposits that significantly impair operation. The solution is either adding thermal insulation to the filter and pipework, or actively heating critical components to maintain temperatures above the dew point, thereby preventing condensate formation and subsequent operational issues.

This issue must be addressed during the design phase, as thermal shocks cannot be easily mitigated once the system is in operation. The system must be structurally designed to accommodate them—primarily through appropriate thermal insulation of pipework and equipment—to minimise rapid temperature fluctuations and reduce the risk of condensation or mechanical stress.

Simultaneously, it is essential to incorporate expansion joints within the pipework to allow for movement during temperature changes, thereby preventing stress, deformation, or cracking of welds. A correctly engineered combination of insulation and expansion elements is crucial for ensuring long-term operational stability.

The filter itself does not “overheat” in a structural sense; rather, the flowing air or flue gases simply reach higher temperatures. If this causes operational issues, it is necessary to add thermal insulation and, where appropriate, manage the temperature of the incoming air.

The surface temperature of the outer casings of filtration equipment should typically remain at a maximum of around 60 °C to ensure operator safety and long-term material stability, without risk of burns or degradation of surface finishes. If this limit is exceeded, additional thermal measures (such as insulation, cladding, or shielding from the heat source) must be implemented.

In this instance, it is highly probable that an unsuitable filter medium has been employed for the specific temperature application. This results in gradual degradation, loss of mechanical strength, and reduced filtration efficiency. The solution is to replace the filter medium with one appropriate for the operating temperature class. Typically, PES is used up to approximately 150 °C, meta-aramid for higher temperatures up to around 200 °C, and ceramic or metal filter media for extreme applications, which can withstand temperatures of about 400 °C and above. Selecting the correct material is crucial for the long-term stability of the filtration system and preventing premature degradation.

In such cases, it is necessary first to repair the damaged sections and then identify the main cause of corrosion. This most often involves moisture condensation in the stockpile area, which, combined with dust and aggressive components of the atmosphere, creates a corrosive environment.

The solution typically lies in improving thermal conditions – namely by adding thermal insulation and, if necessary, heating the stockpile to prevent temperatures from dropping below the dew point, thereby avoiding repeated condensation and subsequent corrosion.

If dust adhesion occurs in the hopper, it is essential to first identify the root cause. This is most commonly due either to moisture condensation, which requires additional insulation or supplementary heating of the hopper to prevent a damp film from forming on the walls, or to an unsuitable hopper slope that prevents the material from flowing freely under its own weight.

The solution involves modifying the hopper geometry and, where necessary, installing shakers (vibratory or mechanical impact devices) to keep the material in motion and prevent it from adhering to the walls. In practice, a combination of measures is often implemented simultaneously—optimising the slope, eliminating condensation, and actively breaking up build-ups using shaker systems.

This phenomenon can be desirable in certain cases, as the cooling of exhaust gases leads to a reduction in volume, which may lower the required fan power and overall energy consumption of the system. However, if condensation occurs during cooling, this constitutes a problematic condition that can lead to corrosion, pipe blockages, and impaired system performance. In such instances, it is necessary to thermally insulate the piping or adjust operating conditions so that the exhaust gas temperature does not fall below the dew point.

In such cases, the most likely cause is an unsuitable material selection or insufficient pipe wall thickness for the given thermal load. The solution involves assessing operating temperatures and mechanical stress, followed by adjusting the pipe design—either by increasing the wall thickness or using a more suitable material, such as stainless steel, to enhance temperature resistance.

At the same time, it is essential to check the thermal expansion of the entire pipeline route, as deformation often arises not only from the material itself but also from inadequate compensation for expansion and improper pipe fixings.

If cracks appear in the pipeline welds, this constitutes a serious structural or installation defect, and the first course of action should be to lodge a complaint with the supplier or the contracting company.

At the same time, it is essential to investigate the root cause of the failure, as welding cracks rarely occur in isolation but are typically the result of inadequate compensation for thermal expansion, improper pipe support, excessive vibrations, or the use of unsuitable materials for the specific temperature and operating conditions.

Without addressing the underlying cause, the problem may recur even after the welds have been repaired.

WARNING – this is a critical condition that must be addressed immediately, or the extraction process should be temporarily halted, as there is a risk of the filter unit catching fire.

Firstly, it is essential to identify the source of sparks and prevent their further transport into the ductwork. Subsequently, it is advisable to replenish or inspect the spark separator, which captures or cools hot particles before they enter the filter. As an additional protective measure, a DSS sorbent dosing system can be installed to help neutralise residual hot particles and reduce the risk of ignition within the filter chamber.

The correct combination of spark separation and sorption is key to the safe operation of the system and protecting the filter unit from fire.

This condition is extremely serious and may indicate either insufficient thermal insulation or, in the worst-case scenario, active combustion within the filtration unit. In such a situation, immediate action is required: take the technology out of operation, close the relevant dampers to restrict air supply, and prevent any potential fire from spreading into the ductwork system. Simultaneously, treat this as an emergency and contact the fire brigade or a trained response team without delay. Once the situation has stabilised, conduct a detailed inspection of the system, identify the cause of overheating or ignition, and implement measures to prevent recurrence.

If hot particles still reach the filter despite the installed spark separator, it usually indicates that their quantity or energy is too high for the device to capture them reliably in a single protection stage. In such cases, you must first inspect the spark source itself and adjust the process so that sparks are not generated with such intensity or are not directly carried into the extraction ductwork. Furthermore, it is advisable to check the placement and functionality of the spark separator, and if necessary, add an additional protective stage, such as a sorbent dosing station, which helps neutralise residual hot particles before they enter the filtration unit. The entire protection system must always be evaluated as multi-stage, because a single separator may not be sufficient under extreme conditions.

If sparks are not captured even with the installed separator, this indicates that their quantity or energy exceeds the current protection level. In such cases, an additional protective stage must be added, for example a sorbent dosing station, which helps neutralise residual hot particles before they enter the filtration unit. At the same time, it is always necessary to inspect the spark source itself and verify whether the process can be adjusted to generate fewer hot particles or prevent them from being directly drawn into the extraction system. The entire protection system must be designed as a combination of prevention at the source and multi-level protection within the ductwork.

If the system did not shut down automatically, this constitutes an emergency situation requiring immediate intervention – immediately take the technology out of operation, close the relevant dampers and prevent further propagation of the pressure wave or fire into the pipework and filtration system. Subsequently, it is essential to contact the fire brigade and the technology supplier without delay so that the situation can be professionally assessed and secured.

Once the situation has been stabilised, a comprehensive inspection of the entire system must be carried out to determine the cause of the explosion (e.g. ATEX conditions, sparks, dust loading or failure of protective elements) and to propose measures that will prevent recurrence of this incident.

In such a case, it is essential to contact the system supplier as soon as possible, because B-Flap is a safety component and its malfunction may indicate that the flap has remained in the closed position, thereby restricting or completely blocking the system’s suction. The supplier must inspect the mechanism, verify correct opening and closing operation of the blade, and carry out any necessary adjustment or repair.

Until the fault is rectified, the system should be operated with maximum caution, or its operating mode adjusted to prevent overload or improper extraction function. However, we recommend shutting down the system.

In such a case, it is essential to contact the technology supplier immediately, as this constitutes a critical safety system that must be inspected and restored to full operational status. Until the fault has been rectified, an assessment of operational risk is required; if necessary, the technology should be restricted or halted to prevent recurrence of an explosion event or further equipment damage.

The ATEX directive itself is not the issue; rather, it is the standard classification of environments with explosive atmospheres. The problem arises when explosive or combustible dust is extracted into equipment that has neither been designed nor certified for the specific ATEX zone in question.

In such cases, a critical situation exists that requires immediate action: the system must be taken out of operation to prevent further transport of the hazardous mixture. Subsequently, it is essential to contact the technology supplier and verify the suitability of the filter design, pipework, and all safety components for the relevant ATEX conditions.

If dust accumulates in the hopper or collection containers, this is normal operational behaviour and requires regular material removal. However, if dust builds up in the pipework, it indicates insufficient transport velocity; this must be increased to prevent settling. If dust appears on the clean side of the filter, it signifies a fault with the filter medium that necessitates replacement, as dust is penetrating through the filtration layer.

In extraction systems handling combustible dust, there is always an inherent risk of explosion that must be accounted for during the design phase as part of the ATEX regime. However, if the risk level rises above normal operational standards, a root cause analysis is required—for instance, to address excessive dust concentration, inadequate spark protection, or unsuitable operating conditions.

To mitigate this risk, multi-layered measures can be implemented, such as installing a spark separator or a sorbent dosing station. The latter helps create a mixture of dust and sorbent, thereby reducing or completely eliminating the material’s flammability and explosivity. Simultaneously, it is essential to ensure that all system safety components—such as spark separators, venting panels, and non-return dampers—are functioning correctly, and to verify that the entire system complies with the designated ATEX category.

In such cases, it is advisable to contact the service team as soon as possible for a fan inspection. This should include cleaning the impeller of dust deposits and performing dynamic balancing of the rotor. Vibrations are often caused by uneven material build-up on the blades or mechanical wear of the bearings.

At the same time, it is essential to check the condition of the filtration unit, as dust ingress into the clean side can cause fan blockage and subsequent imbalance. Such leakage is a typical sign of damaged filter media, which must then be replaced to prevent recurring issues.

In such cases, it is necessary to first inspect the mechanical condition of the fan, particularly the bearings, the impeller balance and any vibrations, as these factors are the most common causes of increased noise. At the same time, it is advisable to check the settings of the frequency converter, because unsuitable speed control can cause acoustic phenomena such as motor whining or resonance at certain frequencies.

By adjusting the control parameters (e.g., changing the PWM frequency or setting the ramp), a significant improvement in the fan’s acoustic performance and a reduction in noise during regulated operation can often be achieved.

In such cases, professional servicing is required, as bearing damage can quickly lead to further mechanical deterioration of the fan, increased vibration and eventual failure of the entire unit. The standard solution involves replacing the bearings; depending on the fan’s design, this may also include replacing bearing shields or complete bearing assemblies. Following repair, it is essential to check rotor balancing and verify smooth operation across the full speed range.

The fan itself does not lose performance, as its characteristics are determined by its construction and rotational speed. If there is a decline in system performance, the cause is invariably either an increase in pressure loss within the system (e.g., due to a clogged filter, ductwork, or exhaust) or a change in control settings—typically a reduction in fan speed via a variable frequency drive as part of vacuum management. It is therefore necessary to check the current operating point of the system, the status of pressure losses, and the control settings to determine exactly what is causing the drop in extraction performance.

In such cases, it is essential to address the issue as quickly as possible, since an unbalanced impeller leads to vibrations, excessive bearing load and gradual damage to the fan. First, the impeller must be cleaned of dust deposits, scale or other materials causing uneven loading.

If the problem persists after cleaning, professional dynamic balancing of the rotor should be carried out, along with an inspection of the mechanical condition of the entire fan. A prompt response is key to preventing secondary damage to the bearings and shaft.

In most cases, this is a situation where the system does not have an adequate operating pressure drop relative to the fan’s duty point. This issue frequently arises when commissioning new units, as the filter is not yet clogged and the system resistance is low. Consequently, the fan operates away from its optimal duty point, drawing excessive airflow and causing the motor to overload.

The solution is either to artificially increase the system’s pressure drop (for example, by throttling with a damper), thereby returning the fan to its correct duty point, or to adjust the speed using a variable frequency drive so that the fan performance aligns with the actual conditions of the system.

This condition indicates that the fan has exhausted its available pressure at the system’s inlet and is unable to overcome the system’s resistance. The most common causes are either a closed or improperly set control damper, blocked or obstructed ductwork, or a significantly clogged filter creating excessive pressure drop.

It is therefore necessary to systematically inspect each component of the system—checking the position of dampers, ensuring ductwork is clear, and assessing pressure losses across the filtration unit—and subsequently address the source of excessive flow resistance.

If fan speeds fluctuate, this is most commonly due to unstable regulation via the PID loop, particularly when the fan is controlled based on static pressure. The control system constantly attempts to maintain the setpoint; however, in a real-world system, delays, changes in pressure losses, and damper switching can cause oscillations around the target value.

The solution lies in correctly tuning the PID controller—optimising the proportional, integral, and derivative components so that the system responds more smoothly, avoiding overshoots or oscillations. It is also advisable to check the stability of the static pressure measurement and the behaviour of the dampers within the system, as these factors can contribute to dynamic changes that the control system reacts to.

If the dampers are unresponsive, it is first necessary to determine whether there is a loss of control signal from the machine or the upstream system. If all dampers fail to respond simultaneously, this is often due to an issue with power supply or the control circuit; therefore, it is advisable to check the fusing and the power feed to the damper source.

Furthermore, the functionality of the actuators and their communication with the control system (e.g., 4–20 mA or bus systems) must be verified, as the fault may lie in signal transmission or centralised control. Once the root cause has been addressed, individual dampers should be tested to verify their full range of motion.

In such cases, it is first necessary to check for the presence of the control signal and supply voltage, as the most common cause is indeed a loss of control or power. If these values are normal, it is likely that the servo actuator itself has failed.

Subsequently, it is advisable to replace it or carry out a service repair, and once operational, verify correct function throughout the entire range of motion to ensure full operability of the control damper.

The damper is a mechanical component actuated by an electric actuator, and the issue may lie either in the mechanics or in the control system. If the damper sticks, the likely cause is mechanical resistance, misalignment, or contamination of the mechanism; it is necessary to check for free movement and the condition of the bearings. If the damper responds but regulates inaccurately or unstably, the problem is more likely related to the actuator’s control—such as an incorrectly set signal, range calibration, or regulation logic. In both cases, a mechanical inspection must be carried out alongside verification of correct control settings and adjustment of the end positions.

In such a case, it is necessary to first check the basic electrical parameters – the presence of power supply, correct wiring of the 4–20 mA loop and continuity of the signal cable, as the most common cause is an interrupted or incorrectly wired signal.

If these basic checks do not reveal the problem, it is necessary to contact the electrical supplier or system service support, because the fault may be at the level of the control unit, converter or the actuator itself.

In such cases, it is necessary to first carry out basic diagnostics of the network status, including checking cabling, switches, IP addressing, and network traffic stability. The issue often lies within local IT infrastructure; therefore, engaging local IT support is advisable so they can verify network communication and load. If the problem cannot be identified at the IT level, it is recommended to contact the electrical supplier or the control system integrator, as the fault may also reside in the communication between the PLC, frequency converter, or servo drives.

Every control system has a certain degree of delay; however, excessive lag leads to unstable control, overshooting values and slow system response to operational changes. In such cases, it is essential to check the PID controller settings (proportional, integral and derivative components), as unsuitable parameters can significantly worsen the delay.

At the same time, it is advisable to review the entire control and measurement section of the system – particularly vacuum sensors, their placement and response times, since delayed measurements can cause apparent regulation lag. If adjusting the parameters does not help, you must contact the electrical supplier or control system integrator for a detailed analysis of the control behaviour.

If the individual sources in the system are not balanced, this results in an uneven distribution of suction pressure across the various branches. The issue can be addressed in two ways: either through electrical regulation by adjusting the fan speed and the overall operating point of the system, or mechanically by throttling the control dampers in each branch. In practice, both methods are often combined – basic hydraulic balancing is achieved using dampers, while fine-tuning is carried out via electrical regulation through a frequency converter to ensure stable and uniform operation at all extraction points.

Vacuum fluctuations are typically caused by an unstable control loop or variable pressure loss within the system. In the first step, it is necessary to adjust the PID (PI) settings of the frequency converter, as poorly tuned parameters lead to overshooting and oscillation around the setpoint.

At the same time, the operational condition of the system must be checked, particularly the pressure drop across the filter, which changes over time and can cause dynamic vacuum fluctuations. If the filtration unit becomes significantly clogged, the control system reacts to these changes with a delay, resulting in system oscillation.

If the system is not adhered to within the designed maximum simultaneous operation of devices, the extraction capacity becomes overloaded. This results in reduced suction power at individual sources, uneven distribution of vacuum pressure, and subsequently, pipe blockages. In such cases, it is necessary to check and adjust the control of simultaneous device operation so that it corresponds to the projected state. If a higher actual level of simultaneous operation is required than was considered in the design, it is necessary to increase the overall performance of the extraction system (fan, filtration or regulation) and then re-hydraulically balance the system.

If swarf accumulates in the pipework, the most common cause is insufficient transport speed, which fails to keep the material moving and allows it to settle. In such cases, it is necessary to increase the flow velocity within the system to ensure reliable swarf transport.

It is also advisable to inspect the pipework design, as any sharp edges, unsuitable joints, rivets, or protruding screws can create areas where material catches and deposits gradually build up. Properly designed pipework should feature a smooth internal surface free from obstructions that could promote swarf accumulation.

Material bridging is a typical issue in the design of hopper sections for filters or silos, where lightweight or fibrous materials form stable arches above the outlet, hindering smooth flow. This most commonly occurs in V-shaped hoppers located above screw conveyors, or in conical hoppers positioned over rotary feeders.

The solution involves either actively breaking up the formed bridge using air blow nozzles, vibration, or mechanical elements, or modifying the hopper design itself. In practice, a flat-bottomed hopper equipped with an installed auger is often employed as a more reliable solution; this actively prevents bridging and ensures consistent material discharge, even for problematic lightweight and fibrous fractions.

This condition is most commonly associated with bridging or insufficient functionality of the discharge system, as mentioned in the previous point. However, apart from structural causes, it is always necessary to check the subsequent part of the process to ensure that there is a proper destination for the material.

Blockages are very often caused by a full container, a malfunctioning rotary feeder, or blocked downstream dust conveyance paths. In such cases, the outlet becomes “closed,” causing the material to accumulate back in the hopper.

The solution therefore involves not only removing the bridge in the hopper but also inspecting the entire discharge chain—the discharge device, feeder, piping, and container—and ensuring free and continuous material flow.

Firstly, it is essential to check the electrical protection, specifically the circuit breaker and the drive power supply, as a loss of power is the primary cause of malfunction. If the power supply is functioning correctly, a very common issue is mechanical jamming of the feeder due to material buildup in the discharge area. In such cases, instead of smoothly conveying the material, the feeder grinds it within its chamber, leading to blockage or overload. The solution involves removing the accumulated material from the discharge area, freeing the rotor, and subsequently verifying that there is a continuous flow of material out of the filter to prevent recurrence.

In such cases, it is necessary to proceed systematically by working backwards from the end of the entire discharge chain, as blockages are usually merely a symptom of an issue further down in the process. The most common causes include an overfilled collection vessel or a blocked pneumatic conveyor, which restricts material outflow and leads to back-pressure buildup in the discharge system. Therefore, the solution is first to inspect and clear the final discharge point, verify the integrity of the pneumatic line, and then remove any build-up within the discharge system to restore a smooth material flow throughout the entire route.

This issue must first be addressed technically by precisely identifying the type of fibres, their source, and the location where winding occurs. In many cases, these are long or stringy materials (textiles, films, insulation, plastics) generated during the process, which subsequently enter the extraction ducting or come into contact with rotating and moving parts of the technology. The solution lies either in limiting the generation of these fibres directly within the process, or in their preliminary separation using a pre-separation stage, such as a rotary separator or pre-cleaner. This prevents them from entering the filtration and pipework sections of the system where they would otherwise wind around components and cause operational issues.

In such cases, it is necessary to first locate the blockage and proceed systematically from the end point of the discharge chain back upstream, as a stoppage in material flow is usually the result of an issue further down the system.

The most common causes are an overfilled collection bin, a blocked pneumatic transport line, or an obstruction in the rotary feeder or discharge hopper. Once the specific cause has been resolved, the entire discharge chain must be cleaned and all connected components checked for clear passage to ensure smooth material flow and prevent recurrence.

This condition arises during the arching of material, where a stable “bridge” forms above the discharge opening, causing the material to cease falling freely. In such cases, the bridge can be broken using air blow nozzles or mechanically with an excavator milling attachment, thereby restoring material flow.

If the issue occurs intermittently, it is necessary to investigate the entire discharge chain for potential causes. This is often due to overfilling of the collection vessel or a malfunction in the dust extraction system from the filtration unit, leaving the material with nowhere to go and causing it to accumulate back in the hopper. Therefore, it is essential to inspect both the hopper itself and the downstream conveying and discharge systems.

If this concerns waste or recycling applications, uneven material flow may also be caused by controlled cycling of individual waste streams, where systems do not run continuously but operate intermittently according to the technology’s requirements. This is entirely intentional in certain processes and forms part of normal operation.

However, if the uneven flow is not a deliberate design feature, it is necessary to verify the stability of the entire system – namely, the consistency of material feed, the function of discharge streams, the condition regarding blockages or overloading in individual branches, and the integration with the drainage and filtration system. Imbalances often arise from a combination of irregular material supply and partial restrictions within the transport or discharge sections of the equipment.

If blockages at the discharge point occur repeatedly, this is usually a design or conceptual issue that cannot be resolved long-term through operational adjustments alone. In such cases, it is necessary to address the situation with the technology supplier, as modifications to the discharge system design are required.

A typical solution involves adding air blow nozzles, which help break up accumulated material and arching, or changing the discharge concept to a flat-bottomed design equipped with a reclaimer cutter. This ensures active and stable material removal even for problematic light and fibrous fractions.

In such cases, it is essential to first check the position and function of the summer/winter mode switching dampers, as incorrect settings are one of the most common causes of recirculation faults. A situation may arise where both dampers are open, both are closed, or they operate in reverse of what the selected mode requires.

This results in improper air mixing or a complete interruption of airflow, leading to ineffective recirculation. After inspecting the dampers, it is necessary to verify their control mechanism, the signal from the controller, and the correct response of the actuators to ensure proper switching between modes.

This condition typically indicates that the filtration unit is not functioning correctly and dust is penetrating into the clean side of the system. The most common cause is damage or degradation of the filter media, which can no longer capture fine particles.

In such cases, it is necessary to inspect the filter and usually replace the filter elements, as damaged media cannot be reliably regenerated. It is also advisable to check operating conditions to prevent repeated overloading or mechanical damage to the new filter.

This condition clearly indicates a loss of the separation capability of the filter medium, meaning that fine particles are no longer being captured adequately. The most common causes are damage, wear or clogging of the filtering material, as well as its degradation due to temperature, moisture or chemical stress.

In such cases, replacement of the filter medium is necessary, as regeneration can no longer restore its original efficiency. After replacement, it is also advisable to check the operating conditions of the system to prevent a recurrence of fine dust penetration.

If dust is returning to the hall from the outlet, this indicates an issue with insufficient filtration or dust bypassing through the filter medium. The most common cause is a damaged or clogged filter medium that can no longer capture fine particles, leading to their release back into recirculation or out of the hall again.

In such cases, it is necessary to inspect the filtration unit and typically replace the filter medium. It is also advisable to check the regeneration status and ensure the tightness of the filtration section to prevent this issue from recurring once the system is returned to operation.

In such cases, it is necessary to check the dimensions and condition of the compressed air distribution system, as this ensures sufficient capacity for filter regeneration. If the distribution network is undersized, blocked or pressure-unstable, inadequate regeneration of the filtration media occurs, leading to increased pressure drop and reduced system performance.

The solution involves repairing or modifying the compressed air distribution system, or replacing it entirely, to ensure a stable supply of air at the required pressure and volume for proper regeneration function.

If drafts are forming in the hall, this usually indicates an improperly designed exhaust airflow from the filtration unit, where cleaned air is discharged at specific points or too rapidly. This condition can negatively impact the working environment and airflow within the hall. The solution involves modifying the exhaust section of the system, for example by installing a draft-free filter sleeve (diffuser) on the exhaust ducting. This ensures even air dispersion and reduces localised currents, thereby eliminating drafts and improving overall air circulation in the space.

Recirculation in itself does not indicate a malfunctioning system; it simply involves returning filtered air back into the space. If assessed as inefficient, it is essential first to verify whether the system simultaneously combines intake points from both the hall and the outdoor environment (e.g., hoppers or external equipment). In such cases, cold and warm air mix, which can cause unstable operating conditions, temperature fluctuations, and degraded overall system performance. The solution lies in separating these modes—specifically by removing or addressing external extraction independently—so that the recirculation loop operates solely with the defined internal environment of the hall, unaffected by outdoor conditions.

In such cases, it is essential to first check the operation of the summer/winter mode switching dampers, as incorrect positioning or faulty damper function is the most common cause of recirculation failure. It may occur that the dampers remain permanently in one position, are open simultaneously, closed simultaneously, or operate contrary to the required mode.

Subsequently, their control and signal from the control system must also be verified to confirm correct switching between recirculation and exhaust airflow. After rectifying the fault, the system should be retested in both modes to ensure proper air return into the hall.

If the hall is overheating, it is essential to first verify the current operating mode of the air handling unit. In such cases, the “summer” mode is typically activated, whereby the extracted and filtered air is discharged outside the building without being recirculated back into the hall.

This ensures effective ventilation of heat generated by both the equipment and the hall space, leading to a gradual reduction in temperature. It is also advisable to check that the overall capacity of the extraction system corresponds to the current thermal loads during operation.

What to do about it? In such cases, you must first contact the technology supplier, as inefficient energy operation is often linked to overall system settings, operating point design, or control mechanisms.

Subsequently, it is necessary to adjust the entire system by optimising flow rates, pressure losses and the fan’s operating point so that the system operates at peak efficiency. At the same time, it is advisable to check and fine-tune the control strategy (e.g., PID control) to ensure it aligns with actual operating conditions and minimises unnecessary energy losses.

In such cases, it is essential to contact the technology supplier first, as the new system must be brought into compliance with the design documentation and contractually guaranteed parameters. Simultaneously, the issue should be addressed through a formal complaint process, requesting that the system be restored to perfect working order—specifically, meeting the designed performance values, pressure losses, and functionality of individual components. Until the fault is rectified, it is advisable to restrict or manage operations in a safe mode to prevent further damage or unstable operation.

In such cases, it is crucial to first determine who was responsible for the brief and who for the system design itself. If the designer developed a solution in accordance with the brief and the supplier delivered according to the plans, a typical situation of shared liability arises, where both parties may point fingers at one another.

In practice, this often leads to disputes over whether the error lay in the design or in the requirements specification. The ideal scenario is therefore for a single responsible entity to handle both the design and implementation, bearing full accountability for the functionality of the entire system from the initial brief through to commissioning.

In such cases, the system fails to meet actual operational requirements because the installed capacity of the fans, filtration, or ductwork does not correspond to the real load. It is essential first to verify whether the initial design data were correctly defined—specifically, the number of extraction points, their simultaneity factor, and dust characteristics.

If under-sizing is confirmed, the system must either be upgraded in terms of capacity (fan power, filtration area, duct dimensions) or its operational mode and equipment simultaneity adjusted to align with the actual capabilities of the network. Additionally, a new balancing procedure is required to ensure even distribution of airflow and prevent local suction failures.

This situation is often unrelated to the technology itself, but rather to the operational mode and adherence to the defined specifications upon which the entire system was designed. If the required simultaneous operation of sources is not maintained, the system operates outside its design parameters, leading to performance imbalance, reduced efficiency, and issues within individual extraction branches.

In such cases, it is essential for the operator to adjust and adhere to the established operational scenario according to which the system was dimensioned. If actual operations do not align with the specifications, either the mode of technology use must be adjusted or a new calculation and regulation of the system must be carried out to match the real simultaneous operation of sources.

If changes to the pipework routing, technology, or filtration unit occurred during implementation compared to the original documentation, the standard procedure is for the supplier to prepare as-built documentation that reflects the actual installed state. However, if changes were made based on different instructions or amendments during the project, it is essential to clearly establish responsibility – whether the change originated from the designer, the contractor, or the client. In such cases, it is crucial to identify who initiated the change and whether it was properly approved, as this determines subsequent liability for system performance and any costs associated with modifications.

In such cases, it is essential first to clearly establish responsibility for the resulting solution—specifically, whether the issue stems from an error in the design documentation or within the execution phase of the supply. If the designer specified a system that was subsequently supplied exactly as per the design but fails to perform effectively in practice, questions arise regarding the correctness of the brief and the design parameters. Conversely, if changes occurred during implementation, liability may lie with the supplier.

In practice, this often leads to shared responsibility between the designer and the supplier, with each party pointing fingers at the other. Therefore, the ideal model for the investor is one where a single entity handles both design and supply, bearing full responsibility for the functionality of the entire system from concept through to commissioning.

In such cases, it is essential first to analyse whether the actual operation aligns with the original specification upon which the system was designed. It is very common for real-world conditions to change in terms of the number of sources, their simultaneous use, material characteristics, or operating modes, meaning that the initial design no longer reflects reality.

Subsequently, responsibility must be established – determining whether the system’s mismatch with operations stems from a flawed design, changes to the specification, or modifications made during implementation. From an investor’s perspective, the most advantageous scenario is when a single responsible party oversees the design, construction, and commissioning, providing full warranty that the system meets actual operational conditions.

In such cases, the equipment must not be accepted, as the conditions for its proper commissioning and functionality verification have not been met. Simultaneously, the supplier must be instructed to rectify the issues by eliminating defects and bringing the system into compliance with the design documentation and contractually defined parameters.

Prior to re-acceptance, a full trial run is required to verify that the system achieves the specified performance, pressure, and operational values.

In such cases, it is necessary to address the situation by raising a complaint with the supplier, as after installation the equipment must comply with the contractually agreed parameters and be fully functional in real-world operation. It is also advisable to specify the issues arising precisely, provide evidence of operational conditions (pressures, outputs, control systems, faults) and request their rectification within the scope of warranty or contractual obligations. Only after the defects have been remedied and functionality verified can the system be considered properly handed over.

In such a case, it is necessary first to distinguish whether the issue stems from a system design flaw or inappropriate control settings during operation. Instability often arises from a combination of poorly tuned PID regulation, variable pressure losses within the system, and the dynamic behaviour of dampers or multiple extraction sources. As a first step, it is advisable to fine-tune the control (particularly the PID parameters of the frequency converter) so that the system does not oscillate around the operating point. At the same time, it is essential to check the hydraulic balancing of the network and the behaviour of individual branches during operational changes. If the problem persists even after optimising the regulation, a complaint should be lodged with the supplier, as this may indicate a design or construction error in a system that lacks stability under real operating conditions.

This condition typically indicates that the rotary feeder is leaking, allowing unwanted false air to be drawn in from the area beneath the discharge point. This negatively impacts the performance of the entire filtration system. The most common cause is wear or damage to the sealing blades, or their deformation or malfunction due to mechanical wear.

In such cases, it is necessary to inspect the condition of the rotary feeder blades and the sealing surfaces. If damage or significant wear is confirmed, replacement is required to restore system integrity and prevent the ingress of unwanted air.

If the system emits a monotonous whistling sound, the most common cause is an air leak in the pipework or at flanged joints. Air passing through narrow gaps generates aerodynamic noise. This phenomenon is often caused by negative pressure within the system, which draws air in through inadequately sealed connections.

The solution involves systematically locating the source of the leak, particularly focusing on flanged joints and pipe connections. Once identified, the joint must be properly reseated or the sealant replaced. While a suitable sealant can provide a temporary fix, the correct approach is always to mechanically repair the joint rather than simply sealing it with silicone, as this only masks the problem without addressing the root cause.

In such cases, a leak or blockage of the regeneration pulse valve occurs, meaning that the valve fails to perform its shut-off function and allows air into the filter chamber. The most common cause is dirt in the coil or the valve itself, which causes it to jam in the open position. Another frequent cause is the freezing of the valve during winter due to moisture condensation in the compressed air and subsequent freezing of the diaphragm.

It is necessary to check the quality and cleanliness of the compressed air, including the presence of water and oil in the system. As a preventive measure, it is advisable to install an adsorption dryer achieving a dew point down to approximately −40 °C to prevent condensation and freezing in the pulse valves.

If the system contains multiple dampers, it is highly likely that one of them has remained inadvertently open or is not functioning correctly, or there may be duct damage and air leakage. In such cases, the system loses vacuum pressure and fails to achieve the design specifications.

It is essential to systematically inspect all dampers within the system, verifying their position and operation, followed by a pressure test of the ductwork to identify any leaks. Once the leak or incorrectly opened branch has been located and rectified, the vacuum level in the system will be restored to the correct value.

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