Collections > Master's Papers > Gillings School of Public Health > A Study of Particle Bounce in Internal Impaction-Based Samplers

Environmental and industrial hygiene samples of fine airborne particles are commonly collected in inertial impaction-based devices. In an ideal form these devices aerodynamically separate particles according to their size. It has been known for some time that solid particles with high Stokes numbers are capable of rebounding from impactor substrates and, consequently, distorting the particle size information obtainable from inertial impactors. However, the phenomenon of particle bounce is poorly understood, and little is known about how particle materials and substrates can affect the amount of particle bounce. In this experiment, a method was developed for the measurement of particle bounce from substrates of three different materials. The particle materials were also varied. The relative bounce of particles over a range of Stokes numbers was compared to literature reported results of similar experiments and to values predicted by a tentative theory of particle capture by surfaces. Experimental results showed good agreement with values expected on the basis of theory. Glass beads showed unexpectedly high collection efficiencies at small Stokes numbers when a dry substrate was used.