Comparative Bounce Properties of Particle Materials

Abstract

A test impactor with a 10-μm 50% cutoff diameter at a flow rate of 7 liters/min was designed to measure particle bounce by the observed penetration to an optical counter. The effects of surface loading and relative humidity on particle bounce were determined, and a set of test criteria was developed to avoid these effects. The particle bouncing experiments were performed for ten common aerosols: ammonium fluorescein, sodium chloride, ammonium sulfate, potassium biphthalate, polystyrene latex, lycopodium spores, paper mulberry pollen, short ragweed pollen, glass beads, and Pinole soil. The differences in the fraction of bounce for different particle materials are discussed. Systematic measurements for ammonium fluorescein revealed a correlation between the fraction of particles bouncing and the particle kinetic energy and aerodynamic diameter. The EPA bounce criterion for PM ₁₀ samplers is criticized in terms of this correlation.