The performance of aerosol centrifuges at unmatched relative humidities between stream and aerosol air

Abstract

Calibration of Lovelace Aerosol Particle Separator, a Stöber type of aerosol centrifuge, was observed to shift when the relative humidities of aerosol stream and stream air were not matched. Systematic investigations were made to study the effect using Dow monodispersed polystyrene latex particles of 0.797, 1.091 and 2.020 μm sizes. Relative humidities (r.h.) were varied in the range of 22% to 80%. When aerosol air was dry (r.h. 22%) and stream air was humid (r.h. 80%), particles deposited farther than the positions corresponding to the matched conditions and the reverse was observed when the aerosol air was humid and the stream air dry. Resolutions were poorer for the unmatched conditions. Results are discussed.