An Investigation of Size Deposition Upon Individual Stages of a Cascade Impactor

Abstract

The particle size deposition characteristics upon each stage of an inertial impactor have been investigated. Disodium fluorescein and kaolin samples of approximately the same median diameter and distribution were collected by inertial impaction. The Delron DCI-6 cascade impactor was used conventionally, with 38 mm diameter glass slides, and a modified arrangement, with 11 mm diameter glass slides placed concentrically within the larger ones. Samples could thus be separated into those depositing at the center of the slide and those depositing at the outer edge. Quantitative and qualitative analyses were performed. It was concluded that size fractionation upon a stage, that is large particles at the center and smaller ones at the outer edge, does occur, however this is complicated by the incidence of bounce and blow off. Further investigations employing monodispersed powders would enable the contribution of the latter phenomenon to be assessed.