Abstract
Collection performances of air filters made of PTFE (polytetrafluoroethlene) filter medium were investigated. Eight types of filters, including one HEPA-grade and one ULPA-grade glass fiber filter for comparison, were examined. Aerosol particle penetrations of the filters were measured by using monodisperse NaCl aerosols ranging 0.02 to 0.2 μm in diameter at air flow face velocity of 5.3 cm/s. Collection performance was evaluated by an index, IP, defined as IP = -log (Pmax) /ΔP, where Pmax is the maximum penetration and ΔP is the pressure drop. The most penetrating particle sizes of the PTFE filters, estimated to be around 0.06 μm, were smaller than those of the glass fiber filters. The collection performance index of the PTFE filters ranged from 17 to 20 kPa-1 although the index of the glass fiber filters were constant at 10 or 11 kPa-1. No differences in the index between HEPA-grade and ULPA-grade glass fiber filters were observed.
