Particle distribution counter for atmospheric aerosols - uses humidity gradient produced by pool of water in bottom of measuring cell

摘要

The particle counter, esp. of atmospheric aerosols, comprises a drying column coupled via a valve (V1) to the measuring cell and humidifier. A pump draws the aerosol into the cell. A second valve (V2) is closed and a bypass circuit is opened (V1, V3). A vacuum pump operated via a valve (V5) to reduce the pressure in an expansion chamber. The valve is closed after a specific interval and the second valve coupling the cell to the chamber is opened - allowing the nuclear condensation to take place. Since the size of the condensation nuclei increases with their proximity to the humidifier surface, the distribution of the particles can be evaluated by means of light extinction or scatter methods.