On identifying and correcting for reentrainment in cascade impactor measurements

Abstract

Correcting for particle blowoff and bounce in cascade impactor measurements by using duplicate stages and a suitable inversion routine is examined. In principle, blowoff and bounce can be accurately determined for the stage preceding a duplicate stage. This determination can be used to improve the size distribution results if the blowoff or bounce can be reasonably estimated for other stages from the duplicate stage data and the reentrainment is not too large. Correction accuracy is not sensitive to error and uncertainties in the shape of collection efficiency curves without bounce, even in the case of severe blowoff, but some knowledge of the dependence of particle bounce on particle diameter is needed when bounce is severe. Blowoff was reasonably well predicted in actual field data for the stage following a duplicate stage pair but blowoff was sometimes obviously less for preceding stages. © 1987 Elseiver Science Publishing Co., Inc.