The removal of particulate matter from gas streams is easier to accomplish than when working with liquids due to the added interaction mechanisms between particulates and the filter membrane’s pore surfaces. Particles may be arrested by the sieve or direct retention mechanism becoming trapped in the pores which are smaller than the particles themselves. Additional mechanisms involved in adsorptive capture by direct interception include gravitation settling and electrical attraction forces.
There may, however, be particles suspended within a gas stream that are too small in mass to undergo inertial impacts. Nevertheless, they may be small enough to encounter a filter surface as a result of diffusional movements. As with inertial impact, the low viscosity of a gas stream allows suspended particles to be trapped by diffusive capture. It is this mechanism that is most responsible for the high filtration efficiencies of air filters. The rate of particle capture is inversely proportional to the square root of the particle diameter.
Due to the large variety of filtration media that is available, understanding the factors that govern the air and gas filter efficiencies will guide you to the correct selection for your specific use.
When selecting the best filter media for air and gas filtration, we recommend you consider the following important properties:
- Water intrusion pressure
- Differential pressure
- Air flow rate
- Bacterial and/or particle retention
- Hydrophobicity and/or oleophobicity
- Thermal stability
- Chemical compatibility
- Compatibility with the preferred sterilization method
If you have questions related to this content or other filtration concepts or how they apply to your specific application, please contact us.
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Author bio
Jacques Hestres, Product Manager for Media – Membrane at Cytiva
Focusing primarily in Medical OEM applications. Throughout his over 25 years at Cytiva, Jacques has held various positions in Customer and Technical Service, Operations Planning, and Product Management. This experience has given him the knowledge of the products, the manufacturing processes used to produce these materials, and an understanding of applications where these are used. Jacques holds a Bachelor’s of Science Degree in Biology from the University of Puerto Rico.
Joseph Vickers - Portfolio Lead, Membrane and Media
A Global Portfolio Leader at Cytiva, responsible for the Membranes and Media portfolio. He has previous experience in global marketing and operations, holding an MEng in Chemical Engineering from the University of Surrey.
Antoine Pozniak - Product Manager Media - Membrane at Cytiva
Antoine has held various roles in sales and marketing throughout his 4-year career in the medical device industry. Throughout those 4 years he has worked with Key Opinion Leaders and developed commercial and technical knowledge. Antoine holds an MBA from Rice University and Bachelor of Arts/Sciences in Interdisciplinary Social Sciences from The University of South Florida.