Universal impactor for particle collection within sampling criteria

摘要

A universal impactor for sampling airborne particles has a slit nozzle that tapers in width along its length. The slit nozzle is in a plate that is thicker near wide parts of the slit and is thinner near narrow parts of the slit. An impaction plate beneath the slit is wider below wide parts of the slit and narrower below narrow parts of the slit. The impaction plate is sloped so that the impaction surface is at a greater distance below wide parts of the slit, and at a lesser distance below narrow parts of the slit. A passage adjacent to the impaction plate allows penetration of unimpacted particles to a particle collector or sensor. An air mover provides flow through the apparatus. The impactor has a particle impaction efficiency that varies smoothly with particle size and a curve of particle penetration efficiency vs. particle size that closely meets any predetermined sampling criteria.