Semi-theoretical and Experimental Results Correlating the Filtration Efficiencies of Meltblown Electrets and Glass fiber paper Challenged by Paraffin Oil, Dioctyl Phthalate, and Sodium Chloride Aerosols at Different Flow Rates

摘要

The European standards (EN 149) uses paraffin oil (PO) as the challenging particles at a flow rate of 95 lpm to measure the performance of a respirator. US NIOSH uses dioctyl phthalate (DOP) as the challenging particles at a flow rate of 85 lpm to measure the performance of the respirators of R- and P-series, and NaCl particles at a flow rate of 85 lpm to measure the respirators of N-series based on 42 CFR 84. The cross sectional area of a respirator is designed to fit the contour of a human's face outline. The cross sectional area of a respirator is therefore constructed to be about 170 cm2. Therefore, a flow rate of 55 lpm is commonly used to test the performance of a flat sheet media for a respirator.Filters for other applications use different standards for their performance testing. There are a number of testing standards. It is exhausted to test the filter media according to these testing standards. It is a common practice to test the flat sheet media of a filter for most of the applications using NaCl aerosol at a flow rate of 32 lpm.It is useful to develop charts that can correlate the filtration efficiencies among the PO at 55 lpm (for European respirators), DOP at 55 lpm (for NIOSH R- and P-series respirators), NaCl at 55 lpm (for NIOSH N-series respirators), and NaCl at 32 lpm (to correlate to other applications). Therefore, if one of the filtration efficiencies is measured, other efficiencies can be obtained using the correlation charts. Filter media for other applications such as medical facemasks using BFE, PFE, BFE can be obtained from the correlation with NaCl at 32 lpm, which was previously developed by the author of this paper.