Characteristics of a cascade impactor under specific conditions

If a dust current is blown out of a nozzle and collides with a flat plate, particles larger than a certain dimension will collide with and be captured by the flat plate, and particles smaller than that will entrain an air current and go astray without colliding with the flat plate. It is therefore possible to measure particle size distribution with the use of a set of impactors, each consisting of a nozzle for classifying a smaller particle size and a flat plate. However, this measurement of size distribution of almost monodispersed particles with an impactor differs from true particle size distribution, because particle size classification does not change rapidly from 0 to 1. The magnitude of theoretical errors in the measurement of size distribution of almost monodispersed particles with impactors, experiments relating to maximum suction flow rate, and a variation in the theoretical diameter of a particle which is collected with a 50% accuracy measured with impactors at high altitude (low temperature and pressure) are presented. It is assumed that the impactors are free from rescattering, rebound, and wall losses.