Development and evaluation of a PM10 impactor-inlet for a continuous coarse particle monitor

Abstract

Conventional PM10 inlets available operate at a flow rate of 16.7 l/min. The purpose of this study was to develop and test a PM10 inlet designed to operate at 50 l/min to be used with a recently developed continuous coarse particle monitor (Misra et al.). Laboratory tests using polystyrene latex particles established the inlet's 50% cutpoint at 9.5 μm. Further evaluation of PM10 inlet was performed in a wind tunnel at wind speeds of 3, 8, and 24 km/h. Tests showed that the 50% efficiency cutpoint as well as the very sharp particle separation characteristics of the inlet were maintained at these wind speeds. Field evaluation of the PM10 inlet was performed in Riverside and Rubidoux, CA. A 2.5 μm cutpoint round nozzle virtual impactor was attached downstream of the developed PM10 inlet. The Dichotomous PM10 Partisol Sampler, operating at a flow rate of 16.7 l/min was used as a reference sampler. The Dichotomous Partisol uses an FRM PM10 inlet operating at 16.7 l/min to remove particles larger than 10 μm in aerodynamic diameter. Commercially available 4.7 cm Teflon filters were used in both the Partisol and the PM10 inlet to collect particulate matter (PM). Results showed good agreement between coarse PM (2.5-10 μm) mass concentrations measured by means of the PM10 inlet and Partisol. Chemical analyses showed excellent agreement between coarse PM concentrations of Al, K, Si, Ca, and Fe obtained by the two samplers. The agreement also persisted for nitrate and sulfate. Finally, the excellent agreement between coarse concentrations of the PM10 inlet and Partisol persisted for wind speeds up to 19 km/h.