Design and performance of a low flowrate inlet
The primary function of an inlet as part of a collection device for aerosols is to extract the aerosol from the atmosphere in an unbiased manner in both calm and windy conditions. A secondary function for some inlets is to remove larger particles from the extracted sample to reduce particulate matter loading in the primary size separation unit. Current inlets in use for sampling particulate matter with aerodynamic diameters less than 10 micrometers (PM{sub 10}) employ impactors, or cyclones. The Federal Reference Method (FRM) for fine particulate matter (PM{sub 2.5}), as it was originally proposed on December 13, 1996 (61 FR 65676), specified a flat-topped inlet design with an internal impactor that aspirates particulate matter from the atmosphere at 16.7 liters per minute. A modified version of this inlet, designed to correct these problems is currently specified as part of the recently promulgated FRM for PM{sub 2.5}. In this application, the inlet serves both to aspirate the PM{sub 2.5} sample and remove the bulk of large ({gt}10 micrometers) particles prior to the subsequent PM{sub 2.5} size fractionation. The question arises as to whether this modified inlet can replace the original inlet-to take advantage of the improved design-in those EPA designated PM{sub 10} samplers and analyzers that use the original inlet. The authors present a discussion of the modified design and preliminary test data comparing the performance of the two inlets, using the EPA Aerosol Test Facility, to determine if the modified inlet could replace the original inlet in the PM{sub 10} methods without altering their performance relative to the regulatory requirements. Paramount to this design effort was that the modified inlet should maintain identical sampling characteristics as the original inlet.
- Research Organization:
- Environmental Protection Agency, Research Triangle Park, NC (US)
- OSTI ID:
- 20002060
- Report Number(s):
- CONF-990608--
- Country of Publication:
- United States
- Language:
- English
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