PM 2.5 Air Monitoring Membrane Filters Tisch PM 2.5 Ambient Air Monitoring Filters are composed of 2.0um PTFE membranes with a 46.2mm diameter, combined with a Polypropylene support ring ideal for robotic air sampling. Their thermally-stable design and natural chemical resistance make them suitable to withstand environmental pollutants that may contain an array of contaminants, yet still deliver clear and precise results. The Polypropylene support ring assures a flat membrane that does not curl, and makes the filter very user-friendly. These filters feature a low tare mass for accurate gravimetric determinations. They meet the requirements for EPA FRM PM 2.5 under 40 CFR Part 50, Appendix L and come sequentially-numbered. Purchase Tisch Scientific SF18040 here 40 CFR Part 50, Appendix L 40 CFR Part 50, Appendix L calls for a filter that meets listed parameters in section 6.0. The below table reflects the criteria that each lot of Tisch Scientific SF18040 PM2.5 Ambient Air Monitoring Filters are tested against for quality assurance, next to this criteria is the referenced section number from 40 CFR Part 50, Appendix L that calls for these parameters. Criteria SF18040 Characteristic Range/Test Method 40 CFR Part 50, Appendix L Section Filter Media PTFE Teflon N/A 6.2 Filter Thickness (um) 40 ±10 6.5 Filter Diameter (mm) 46.2 ±0.25 6.1 Filter Pore Size (um) 2 ASTM F 316-94 6.4 Total Support Ring Thickness (mm) 0.38 ±0.04 6.3 Support Ring – Width (mm) 3.68 ±0.00, -0.51 6.3 Particle Retention (0.3 um) 99.7% ASTM D 2986-95a 6.8 Pressure Drop (0.3um) @ 16.67 liters/min. 30 cm H2O ASTM D 2986-95a 6.6 Alkalinity 25 u eq/g of filter EPA/600-R-94/038b,Section 2.12 6.10 Weight Loss (ug) <20 Above 6.9 Loose Particles (ug) <20 Above 6.9.1 Moisture Pickup (ug) <10 Above 6.7 Requesting Samples Would you like to sample some of our air monitoring membranes prior to purchasing? Tisch Scientific offers free product samples for testing purposes. In order to request samples simply click the green, “Request a Sample,” button on any product page. Or click here. We will promptly send you samples within a business day.