Abstract
Several filter media were evaluated by using liquid (0.3 µm DOP) and solid (approximately 0.3 µm polystyrene latex) test aerosols. Data were obtained for each medium at velocities ranging from 4 to 190 fpm. Below 100 fpm, Whatman 41 filter paper has a significantly higher efficiency when tested with solid aerosols. Below 40 fpm, IPC 1478 also has a significantly higher efficiency when tested with solid aerosols. Instrumentation limitations prevented measuring any significant differences for the high-efficiency media tested. Aerosol agglomeration and charge effects were eliminated by using an impactor and by establishing charge equilibrium for the solid aerosols. Average electron charge on latex particles was reduced to 0.7, and the test aerosol consisted of 86 to 97% single particles. The effects of filter loading on efficiency and pressure drop was also measured. Whatman 41 efficiency was significantly increased owing to loading with polystyrene latex aerosols. This did not occur with DOP.