Development of a Sharp-Cut Cyclone for Ambient Aerosol Monitoring Applications

Aerosol samplers for ambient PM2.5 are required to possess a steep aerodynamic particle size selection curve, i.e., a 'sharp cut' at 2.5 mu m aerodynamic diameter. For long-term and continuous PM monitors the selector system also requires low maintenance and the ability to operate at high loadings. While a sharp cut is easier to achieve with an impactor-based selector, the other require ments are more easily met with a cyclone. Four alternative PM2.5 selectors were tested against these criteria: two were pre-existing commercial designs and two were novel cyclone prototypes. The main aim of the work was to assess the characteristics of the selectors when clean and under various loading conditions. The aerodynamic size-selection characteristics of the PM2.5 selectors were tested before and after loading with dust, under both laboratory and field conditions. Aerosol penetration measurements were made using an Aerodynamic Particle Sizer. Many repeat tests were performed on two specimens of the Well Impactor N...