Achieving consistent penetration test results in respiratory filter and filter media testing

T. Johnson*, J. Johnson, A. Avenido, TSI Incorporated, USA; Juergen Spielvogel, TSI GmbH, Germany

Equipment used for testing products needs to give consistent results. Usually test equipment can be verified by tracing the results to a standard. For respiratory filter testing commonly used standards are ISO 16900-3, 42CFR part 84, and GB2626. These standards typically define key parameters for testing such as flow rate, aerosol concentration, count median diameter, geometric standard deviation, and ambient conditions. Some standards also specify the test equipment. Still, measurements that are compliant to the standards requirements don’t necessarily result in consistent penetration test results. While count median diameter and the geometric standard deviation is the most accurate way to define a submicrometer particle size distribution, the aerosol undergoes changes in the aerosol path of the filter tester that can change the size distribution.
Light scatter photometers are a standard method for testing air filter media and some filter types. They have a long history and have the benefit of being able to measure particle concentrations much higher than particle counting instruments. This makes them suitable for penetration and loading tests of filters. Light scatter properties of submicrometer particles are proportional to the sixth power of the diameter resulting in the largest particle contributing the vast majority of the light scatter signal. Therefore, small changes in the upper end of the distribution can have significant effects on the signal and this changes the measured penetration of particles through the filter.

Recently, TSI developed a new model filter tester, the model 8130A, which replaces the model 8130, a filter tester that over more than 20 years has become the reference instrument in many labs. In order to obtain continuity of measurement results a test matrix was devised and executed to compare the two filter testers (models 8130A and 8130) that consisted of

In conclusion, these tests showed...

Session: G10 - Short Oral + Poster Presentations I
Day: 14 March 2018
Time: 14:45 - 16:45 h

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