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Testing of a Personal Filter Cassette With a Circumferential Orifice.

McCawley-M; Burkhart-J; Baron-P; Dollberg-D
NIOSH 1983 May:21 pages
A new personal filter cassette with circumferential orifices for personal inhalable dust concentration measurements was tested using coal dust and compared to standard closed face and open face cassettes. The new cassette has four orifices separated by small posts with a slot like geometry located circumferentially around the side of the cassette filter holder. The collection of coal dust was sampled in a laminar flow chamber with the three types of cassettes at different orientations to the air flow. Uranine tagged potassium biphthalate particles were used to test the uniformity of distribution on the filter surface. The test results indicated that the circumferential cassette appears to give a uniform distribution of dust across the filter surface. As this surface is protected like the surface in the closed face cassette, this cassette may have some advantages over either of the other two. The angle of the cassette orifice relative to the air flow is significant also in that the larger the angle the larger the possible error in the results. With the circumferential design of the orifice, it is impossible for the air movement to be at an angle of greater than 90 degrees. This is not true for the other two models, as air can strike at an angle of 180 degrees. With the new cassette it is possible to sample particles under 10 micrometers, whereas the orifices of the other two cassettes do not allow this size to be monitored.
NIOSH-Author; Sampling-equipment; Air-sampling-equipment; Air-sampling-techniques; Air-samplers; Coal-dust; Dust-analysis; Dust-collectors; Dust-samplers; Dust-sampling;
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Division of Respiratory Disease Studies, NIOSH, U.S. Department of Health and Human Services, Cincinnati, Ohio, 21 pages, 10 references