Design and performance of a low flowrate inlet
Several ambient air samplers that have been designated by the US EPA as Federal Reference Methods (FRMs) for measuring particulate matter nominally less than 10 micrometers (PM-10) include the use of a particular inlet design that aspirates particulate matter from the atmosphere at 16.7 l/m. Several studies have indicated that, under some atmospheric conditions, design flaws in this PM-10 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. The new inlet is currently used as part of the PM-2.5 FRM to remove the bulk of large particles prior to PM-2.5 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 PM-10 FRM samplers without altering their PM-10 performance relative to the FRM regulatory requirements. 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.
- Research Organization:
- Research Triangle Inst., Research Triangle Park, NC (United States); Environmental Protection Agency, National Exposure Research Lab., Research Triangle Park, NC (United States); Research Triangle Inst., Durham, NC (United States)
- Sponsoring Organization:
- Environmental Protection Agency, Washington, DC (United States)
- OSTI ID:
- 362156
- Report Number(s):
- PB--99-143356/XAB; CNN: Contract EPA-68-D5-0040
- Country of Publication:
- United States
- Language:
- English
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