Eurovent 4/26: How to determine the service life of molecular filters
Molecular filters have a decisive advantage over particle filters: Only molecular and gas filtration can remove the smallest of contaminants in harmful gases and vapors from the air using specific technological processes. But when should you replace a molecular filter? The new Eurovent 4/26-2024 guideline gives recommendations for when to replace molecular filters and specifies when they have reached the end of their useful life.
How exactly does molecular filtration work? How are molecular filters structured, and which materials are used?
MANN+HUMMEL uses activated carbon, zeolites, aluminum oxides, or ion-exchange resins as filter media for molecular filters. All these media share one characteristic: They have a large internal surface. Various activation processes (e.g., hot airflow, steam, or CO2 flow) are used to process the chemical structure of the filter media and improve its pore structure as well as enlarge the surface area. Activated carbon's high porosity therefore ensures a large active surface area per volume unit, reaching—and exceeding—well over 1,000 m2 per gram of material. In some cases, it can even go up to 2,000 m2/g. Consequently, not much filter material needs to be used to adsorb large quantities of pollutant molecules in molecular filters. This process is based on adsorption forces or chemical reactions.
At what point does the filtering effect of a molecular filter decrease? How long is its service life, and when do molecular filters actually need to be replaced?
The more harmful gases and vapors pass through the ventilation system, the more harmful molecules will accumulate on the surface of the filter medium. Even if only one teaspoon of activated carbon creates an inner surface that is about the size of a soccer field, the filter medium will eventually reach its natural saturation limit during prolonged use of the molecular filter.
The new Eurovent 4/26 guideline helps determine the service life of molecular and gas filters, as follows:
- Increased of pressure drop in the ventilation system is not an adequate indication for replacing the filter.
- We recommend continuously measuring the concentration of harmful gases and vapors immediately downstream of the air filter. As the efficiency of the filter decreases, the concentration of pollutants penetrating the filter and contained in the airflow downstream of the filter increases accordingly.
- Molecular filters must be replaced once the critical pollutant concentration has reached the maximum permissible threshold downstream of the air filter.
- If it is not possible to monitor the gas concentration downstream of the air filter, we recommend replacing the molecular filter after a certain period of use, but this also depends on certain factors such as ambient conditions. Ask our experts at MANN+HUMMEL for more detailed information.
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