DEVELOPMENT OF A LOW-PRESSURE AEROSOL SAMPLER

A low-pressure aerosol sampler (LPAS) has been built to interface betw een low-pressure source chambers and aerosol/gas-analysis systems oper ating at atmospheric pressure. The LPAS is computer controlled and tak es batch samples of aerosol at low pressure from a source chamber, rep ressurizes the sampled aerosol to atmospheric pressure, and then deliv ers the sampled aerosol at steady flow to analysis instruments operati ng at atmospheric pressure. The LPAS is able to (1) sample and deliver particles in the 20-1000 nm size range with a minimum simulated trans fer efficiency of 50% at 300 Pa, (2) maintain a background aerosol con centration of 2 [#/cm(3)] in the delivered aerosol flow (the backgroun d concentration results from internal particle generation), and (3) de liver a continuous flow of aerosol for arbitrary periods of time, ther eby providing a virtual interface between low-pressure source chambers and atmospheric-pressure analysis instruments. (C) 1995 American Inst itute of Physics.