Calibration and testing of samplers with dry, polydisperse latex

A new method for measuring the collection efficiency of an aerosol sampler as a function of particle size has been developed, featuring the use of dry , polydisperse latex particles. Test aerosol is generated by placing a poly disperse latex powder sample into a fluidized bed of glass beads. An Aerody namic Particle Sizer (APS) measures the particle size distribution entering and leaving the sampler's size-selector, yielding the penetration efficien cy. The use of dry latex minimizes the "phantom'' particle problem inherent with the APS by avoiding the generation of high concentrations of small pa rticles such as those produced by nebulizers. In addition to having useful properties for determining particle size cutoff characteristics, including spherical shape, near-unit density, and white color, latex particles afford a test for the presence of particle bounce and reentrainment, A complete e fficiency measurement can be made in a little over three minutes, facilitat ing experimentation with parameters such as sampler how rate, which require repeated measurements, The method has been used extensively for the develo pment and calibration of respirable and PM-2.5 samplers.