Abstract
In this study various types of flat sheet electret filter media including tribocharged polypropylene/acrylic, corona charged polypropylene, fibrillated electret film, and new advanced electret media have been compared with mechanical filter media (fiber glass) using aerosol filtration tests designed for particulate respirators. The number of layers, and thus the total mass and pressure drop, of the media were varied while the filter area exposed to the aerosol and the aerosol flow rate was held constant (constant face velocity). Tests included challenges with sodium chloride and dioctyl phthalate (DOP) aerosols per NIOSH 42 CFR 84 specifications for particulate respirator certification. Initial filtration efficiency and pressure drop and the same during loading were determined. Results revealed significant differences in filtration performance and loading behavior among the various media. It is concluded that respirators can be designed for all nine 42 CFR 84 classes using electret filter media without sacrificing low pressure drop, light weight, or user comfort.