Electric aerosol particle counting and size distribution measuring system for the 0.0 15 to 1)c size range'

An electrical particle counter and size analyzer system having the following charac-teristics has been described. (1) Sizing range from 0.015 to 1. 2 ~. (2) Classification range from 0.015 to 0.6 y at 28 l/m aerosol sampling rate. (3) A unique unipolar diffusion charger that is stable, controllable and capable of near optimum charging performance. (4) A versatile mobility analyzer capable of discrete classification of particles with mobilities from 0.01 to 0.0002 (cm/sec)/(volt/cm) at aerosol flow rates up to 57 l/m. This analyzer is unique in using a filter located at the aft end of the current collector. This separation of the collecting electrode and the current collector permits the use of collector voltages up to 30 KV while maintaining background currents below 10-la amp. ( 5) Although the instrument described here is only semi-automatic, a completely automatic version of the EPC is entirely practical. An automatic EPC used together with an automatic CN and optical counter would permit continuous automatic siz