Multi-lobe pump for particle counters

摘要

A pump establishes gas flow in a particle counter. A pair of shafts having lobes is mounted in a first housing and serves to establish a gas flow path through a second housing which defines a view volume where particles are counted by light scattering or obscuration of a beam intersecting the light flow path. The lobes of the first housing do not contact each other or the walls of the housing, thereby limiting particles to those suspended in the gas flow.