AFS North Central Chapter Meeting

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Methods for Testing Air Filter Efficiency
Tim Johnson, TSI Incorporated

Today’s Air Filtration market has had many challenges related to the COVID-19 pandemic. The need for respirators and medical masks originally exceeded capacity and alternative sources for these devices and for other face coverings resulted in new manufacturers in this market. In addition, there has been a push for higher efficiency filters for HVAC applications and also for portable air cleaners to clean indoor spaces. These factors contributed to a high demand for air filter testing equipment This presentation will talk about various automated testers and components that can be used for testing air filters.

Abstract – METHODS FOR TESTING AIR FILTER EFFICIENCY:
There are different test methods used for testing filters in different applications. Respirator filters are tested according to standards that are required for certification.  Standards for ventilation filters and portable air cleaners are voluntary standards that are widely used in industry as a way of comparing products.

TSI has been involved in making products for testing air filters for over 30 years. Different technologies are used for testing filters used for different applications. Photometer based testers are used for testing respirators and widely used as quality control for filter media. To get information about the filter efficiency versus particle size a Fractional Efficiency Filter Tester can be used to get that information around the Most Penetrating Particle Size (MPPS) of the filter. For filters used in ventilation and similar applications, the efficiency at larger particle sizes requires different components and large test ducts.

This presentation we review the various standards and the equipment used to test those standards.

Tim Johnson has a Bachelor’s degree in Physics from Macalester College in St. Paul Minnesota. He has worked at TSI Incorporated for 43 years and has worked with the Automated Filter Tester products since 1990. He is currently Product Specialist in the Particle Instruments product group. He is responsible for particle instruments and product applications using automated filter test equipment and components used in filter testing applications.

He is actively involved a number of groups that develop air filtration standards. He is on the ASHRAE TC 2.4 committee (Particulate Air Contaminants/Removal Equipment). He is a member of ISO/TC142, expert on ISO/TC142/WG 3 (general ventilation filters) and is a co-convener of JWG11 (ISO/TC142 and IEC/TC59 – Portable air cleaners).  He is a member of ASTM committees on Medical Face Masks and was part of the working group that developed the new Barrier Face covering standard (F3502).