Methods - Breathability
This setup was used to measure pressure drop of filter material at several face velocities (5.3, 8.3, 16.5 cm/s). The 8.3 cm/s velocity corresponds to the NIOSH standard.
Methods - Filtration
This test setup remained identical for both upstream (US) and downstream (DS) sampling. For a DS measurement, a test filter was placed in the filter holder –whereas for the US measurement, the filter holder remained empty during sampling
•JHU/APL used two instruments for PFE testing, a Scanning Mobility Particle Sizer Spectrometer (SMPS) and an Aerodynamic Particle Sizer (APS). The range of the SMPS for the scope of this testing was 0.0151 µm to 0.4783 um and the range of the APS was 0.523 µm to 20 µm.
•The dotted vertical line on the subsequent filtration efficiency plot represents the split between SMPS data and APS data.