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DESIGN AND PERFORMANCE OF A LOW FLOW RATE INLET
Citation:
Tolocka, M P., F L. Chen, R W. Wiener, T. M. Peters, AND R. W. Vanderpool. DESIGN AND PERFORMANCE OF A LOW FLOW RATE INLET. Presented at Proceedings of 92nd Annual Meeting and Exhibition of the AWMA, St. Louis, MO, June 20-24, 1999.
Description:
Several ambient air samplers that have been designated by the U. S. EPA as Federal Reference Methods (FRMs) for measuring particulate matter nominally less than 10 um (PM10) include the use of a particular inlet design that aspirates particulate matter from the atmosphere at 16.7 1pm. Several studies have indicated that, under some atmospheric conditions, design flaws in this PM10 inlet can cause it to fail to reject precipitation and small insects, allowing them to reach the sample filter. Therefore, the design of this inlet has been modified to minimize this possibility, and the modified inlet is currently used as part of the PM2.5 FRM to remove the bulk of large particles prior to PM2.5 size fractionation. The purpose of this study is to compare the performance of the modified and original inlets, using the EPA Aerosol Test Facility (ATF) wind tunnel, to determine if the modified inlet could be used with PM10 FRM samplers without altering their PM10 performance relative to the FRM regulatory requirements. The test follows the wind tunnel Standard Operation Procedures as outlined in Subpart D of Title 40, Part 53 of the U. S. Code of Federal Regulations. The procedure for this investigation includes the simultaneous sampling of monodisperse aerosol through both the original and modified inlets as well as an isokinetic sampler. The isokinetic sampler provides a basis for determining the sampling efficiency of each inlet. The sampling protocol is repeated for liquid particles ranging in aerodynamic diameter from 3 to 25 micrometers. Solid particles are used to check for particle bounce. A sampling efficiency curve has been developed for 3 to 25 micrometer particles for wind speeds of 2, 8, and 24 km/hr and the 50 % cut-point determined. The data presented from this comparison of the performance of the modified and original inlets give a quantitative evaluation on the efficacy of the modified inlet for PM10 samplers.
This paper has been reviewed in accordance with the U.S. Environmental Protection Agency's peer and administrative review policies and approved for presentation and publication. Mention of trade names or commercial products does not constitute endorsement or recommendation for us.