ELECTROSTATIC EFFECTS IN AEROSOL SAMPLING AND FILTRATION

Deposition of aerosol particles during sampling and transport through tubes has been studied by considering the effect of diffusion, sedimentation, inertial impaction and turbulent deposition. The pertinent equations are summarized and graphs presented showing particle deposition as a function of particle size, tube diameter and length, and flowrate. The influence of electric charge on particle deposition has been studied by measuring the penetration of monodisperse. charged aerosols through metal and plastic tubings. The result has been expressed in terms of a mean surface electric field on the plastic tubing surfaces. For Polyflo® and Teflon®, the mean surface electric field has been found to be in the vicinity of 50–200 V cm−1 and, for Tygon®, essentially zero. The surface electric charge on several commonly used filters has also been measured and the influence of this charge on particle deposition in the filter-housing during sampling has been studied.