Do you have any questions about COALSI products?

If you look at odour filters for street canals, for example, many filter systems channel rainwater through the filter medium, which also flushes suspended matter and fine sand particles into the filters. As a result, the porous surface of activated carbon, for example, is added by dirt particles and can no longer bind odor-causing substances. As a result, these types of filters must be regularly cleaned, rinsed or the filter material replaced so that there is no seal.
Other systems that do not use activated carbon, such as wood chips to reduce odors, even need to be watered during long periods of drought to maintain their functionality. This is time-consuming and uneconomical.

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The COALSI odour filters, on the other hand, are designed in such a way that rain or condensation water is directed past the filter mat and the filter medium never comes into contact with water. As a result, the activated carbon filter mat can exploit its full potential at any time and effectively and sustainably neutralizes odorous air from ducts or exhaust air.

Thanks to the unique honeycomb structure of COALSI filter mats, activated carbon achieves a high specific surface area and can therefore bind odors more effectively. The open pore structure ensures uniform air distribution, which optimizes the contact time between air and the activated carbon. Biofilters and activated carbon fillers lose efficiency due to moisture or soiling and close the channel (!) , whereas the adsorption performance of COALSI filter mats remains stable in the long term.

The activated carbon filter mats are easy to handle and replace without the need for complex replacement of fillings or wood chips. In addition, the filter mats require less space because they work more efficiently and do not require a thick layer of biological material. They can be integrated into existing systems to save space or used for modular systems.

Another advantage of activated carbon filter mats is reduced maintenance costs and high adaptability to different air flows and pollutant concentrations. They can be used in a wide variety of applications — from street sewer filters to small exhaust systems to large industrial filter systems.

The term “hybrid filter” comes from the fact that the COALSI filter mats combine several filter technologies in order to achieve higher efficiency and a longer service life. In concrete terms, this means:

Physical filtration: Activated carbon binds odor-causing substances to the surface through adsorption This process is based on physical forces and takes place without a chemical reaction.

Biological filtration: Microorganisms from the exhaust air settle on the loosely structured PU mat of the COALSI filters. The microorganisms effectively break down hydrogen sulfuric substances from the exhaust air, and the filter performance is significantly increased.

Chemical filtration: Activated carbon is a highly reactive chemical compound. COALSI hybrid filters make use of this, as odor-causing molecules in the exhaust air are usually just as reactive. This causes the molecules in the exhaust air to react with the surface of the activated carbon and effectively bind odor-causing substances. The standard hybrid mats already filter a large part of the odor-causing substances from the exhaust air. In addition, we offer you special mats that are impregnated with chemical reagents to increase the chemical reaction and convert it into less annoying, odorless substances. The special mats are particularly effective against:

- alkaline gases, e.g. ammonia, amines

- acidic gases, e.g. sulfur dioxide

- Hydrogen sulphide H₂S

The COALSI odour filters are all equipped with hybrid mats, which are made of polyurethane (PU) and are enriched with activated carbon. The unique honeycomb structure of the filter mats gives the activated carbon an enormous area to which odor-causing molecules are bound. Thanks to the specific properties of activated carbon, odors are neutralized using physical, biological and chemical processes.

The activated carbon used in our filters consists of more than 90% carbon with a large internal surface area (approx. 1200 m²/g). 4-5g of charcoal is therefore approximately the area of a soccer field. This area is used to absorb unwanted pollutants from the air.

There are special impregnations for cases of hardship when activated carbon alone cannot filter all gases out of the air. Compared to the standard mat, these are even more effective against:

- alkaline gases, e.g. ammonia, amines
- acidic gases, e.g. sulfur compounds
- hydrogen sulphide H₂S

Find out more about COALSI filter technology here.

As standard, COALSI odour filters are equipped with hybrid mats, which already bind a wide range of odor-causing molecules. In addition, we offer you three different special mats, which are designed for special cases of hardship. The special mats are specially impregnated to increase the reactivity of activated carbon for the corresponding areas of application and to bind odor-causing substances even more effectively. This makes the special mats more effective against:

• alkaline gases, e.g. ammonia, amines
• acidic gases, e.g. sulfur compounds
• hydrogen sulphide

The short answer is: No, filters based on activated carbon are never maintenance-free — like no filter that absorbs odors or pollutants, by the way. Activated carbon saturates over time and loses its filtering effect. The filter media must therefore be replaced regularly.

A replacement is essential because activated carbon binds odour molecules through adsorption. As soon as the pore structure is saturated, the charcoal cannot absorb any further odorous substances. A change is necessary to ensure consistently high filter performance.

This applies not only to activated carbon filters, but also to other filter systems. Wood chips can sock due to moisture and lose their filter effect in the process. Other granules that are used to neutralize odors also become saturated and must be replaced.

You can compare this with everyday examples: The air filter in the car must be changed regularly, as must the oil filter or the grease filter in the extractor hood. No filter is infinitely effective — regular maintenance and replacement are essential to ensure reliable filter performance.

How often filters need to be replaced depends on the use and concentration of the odorous substances. In normal areas of use, the service life can be 12 to 18 months. Exact change intervals depend on the respective conditions and should be checked regularly. Thanks to the unique honeycomb structure of the COALSI filter mats, activated carbon is prevented from soaking, which significantly increases the service life of the filter media.

Find out more here.

Volume flow, filter size, filter height, the combination of ingredients and biological factors have an influence on the service life. Microorganisms settle on the filter media and extend the life of the filters. The impact of these little helpers cannot be predicted exactly, so it is difficult to say how long the filter mats will last. However, experience shows that the filter mats should generally be replaced after 12 months in order to keep the odour filters fully functional.

In principle, the filters should be checked and inspected once a year. If a replacement of the filter mats is indicated, they can be changed easily and simply.

A possible pressure loss always depends on the volume flow, the filter size, the filter height and the combination of air ingredients as well as the prevailing humidity. Studies and practical tests — including by the Institute for Underground Infrastructure (ICT) — have proven that there are extremely low flow resistances when the COALSI odour filter is installed.

This is due to the honeycomb structure of the COALSI filter mat, which offers a high flow rate. The variance in flowability is within a range that is not significant in practical use.

Therefore, installing the COALSI odour filter results in a negligible loss of pressure, which generally does not affect the airflow in the duct.

A plastic body offers numerous advantages over other materials such as metal or wood, particularly in demanding areas of application. Thanks to its high resistance to corrosion, plastic is ideal for environments in which moisture or aggressive substances such as hydrogen sulphide or ammonia occur. Unlike metal, plastic does not rust, which ensures a longer lifespan and less maintenance.

In addition, plastic is significantly lighter than metal, which makes it easier to install, transport and maintain the filters. Thanks to flexible manufacturing, plastic bodies can also be produced in tailor-made or modular designs that are perfectly tailored to specific requirements. Its smooth surface makes cleaning easier and prevents the accumulation of dirt or microorganisms, which improves hygiene.

Another advantage is the chemical neutrality of plastic, as there are no adverse reactions with the activated carbon or the filtered pollutants. At the same time, the material offers high impact resistance and dimensional stability, so that it works reliably even in harsh environments. Plastic bodies are also less expensive to produce and more environmentally friendly, as modern plastics can be recycled and reused. The COALSI odour filters all consist of up to 80% recyclate — i.e. used and remanufactured plastics, which increases the sustainability of our products. In addition, residual material or rejected goods are returned to the production circuit, which further increases the sustainability of our products.

In summary, a plastic body is the ideal choice to ensure a long-lasting, efficient and economical solution for odour filters.

Plastic manhole covers offer numerous advantages over conventional grate covers. A major advantage is their lower weight, which makes handling and installation easier. They are also corrosion-resistant as they do not rust and are resistant to chemicals, which extends their lifespan. Another advantage is electrical insulation, as plastic does not conduct electricity and therefore increases safety in certain areas. Plastic covers are also convincing when it comes to weather resistance, as they are UV-stable, moisture-resistant and resistant to extreme temperatures. The COALSI FlexiGrid is also optionally equipped with an anti-slip surface (slip resistance R13), which improves safety. Another advantage is low noise pollution, as plastic covers are significantly quieter than gratings when loaded or moved on. They also offer environmental benefits, as the COALSI FlexiGrid consists of 80% recycled materials and is more sustainable than galvanized metal covers.

FlexiGrid can also be individually adapted to your needs and can be adapted to the conditions on site with a simple tool. It is also easy to equip it with an odour filter.