Removal of ultrafine particles and particles of the most penetrating size by new intermediate class filters

Paper in proceeding, 2011

Twenty-three new filter samples, including three different medium types, were tested in a small scale test-rig using a Scanning Mobility Particle Sizer (SMPS). The filtration efficiencies for ultrafine particles (UFPs) and particles of the most penetrating particle size (MPPS) were determined. The filters were of class F5-F9 according to the European filter standard, which roughly corresponds to MERV9-MERV15 according to the US-standard. The filters were challenged by the indoor aerosol prevailing in the laboratory. Additional tests were made using an oil aerosol. With the indoor aerosol, charged synthetic filters showed substantially higher MPPS efficiencies than glass fiber and uncharged synthetic filters of the same class did. With the oil aerosol, the different filter media types, belonging to the same filter class, showed similar efficiencies. The oil aerosol drastically reduced, or eliminated, the electrostatic filtration mechanism. For example F7 and F8 filters not influenced by electrostatic mechanisms typically showed 40% and 50% removal of MPPS particles respectively.