Design, calibration, and field test of a cyclone for PM1 ambient air sampling

Abstract

Ambient air sampling at a flow rate of 16.7 Lpm (1 m3/h) has been well established with the adoption, within the USA, of the EPA regulations governing PM2.5 sampling. Subsequent to the adoption of the new regulation, problems were encountered with the impactor technique utilized for establishing a PM2.5 cut (D50 = 2.5 μm aerodynamic equivalent diameter, A.E.D.). In order to avoid the depression in the cut point engendered by a buildup of collected material on the impactor stage and to extend the operating interval between cleanings, a cyclone was developed to replace the impactor. Although not an adopted standard, PM1 has a practical appeal in that it represents the smallest cut point that can practically be assessed for long periods of time at high flow rates utilizing inertial techniques. Further relevance is attributed to this cut by interest in particulate matter related to diesel engine emissions. A new version of the sharp cut cyclone (SCC) was constructed with the aim of obtaining a cut point at D50 = 1 μm at a flow rate of 16.7 Lpm. The dimensions of the cyclone were calculated using the SCC design model by Kenny and Gussman. Field studies were conducted to validate the PM1 cyclone and to compare the results to colocated PM10 and PM2.5 concentration measurements.