Issue link: https://www.e-digitaleditions.com/i/1518209
20 April 2024 Inhalation ing through the filters. e history of most of these filters is in the measurement of total suspended solids found in natural or laboratory water streams. ese manufacturer-provided performance statements for the filter cartridges (Table 1) and filter media (Table 2) are both sparse and incomplete, and importantly, in the context of our present scope, contain very little information pertinent to air flow resistance. One manufacturer, I.W. Tremont (Hawthorne, NJ), maintains organized product specifications for its binderless glass-fiber filters (https://iwtremont.com/ information/dataSheets.php). ose data are still sparse and are obtained under conditions much dif- ferent than those used in inhaler testing. Filter testing methods We tested each filter with a simple flow system consist- ing of a protective inlet filter, a flow meter, a filter disc Existing filter specifications We gathered into Tables 1 and 2 any qualitative or quantitative specifications that we could find that were related to air flow and particle collection for the fil- ters we evaluated. Both cartridge filters in Table 1 are microporous sheets of polypropylene that are pleated to provide substantial (but unspecified) filter surface area in a given filter housing. e pleats are evident in the Pall product because the housing is a transparent plastic. ese filters are hydrophobic, a quality that can be important in patient health care and in nebulizer testing but that is irrelevant in most inhaler testing. All the disc filter media in Table 2 are called "bind- erless" glass-fiber filters by the manufacturers. at aspect means that the filters are 100% borosilicate glass, meant to ensure product stability at elevated temperatures (not relevant to inhaler testing) and to contribute no contaminants to the air or water pass- Product Name Manufacturer Vendor Specifications GA-55 Advantec, Toyo Roshi Kaisha, Ltd. Tokyo, Japan Sterlitech Corporation 1 Auburn, WA, US 99.9% Efficiency for gas filtration Grade A I. W. Tremont Company, Incorporated Hawthorne, NJ, US Sterlitech Corporation 99.96% Capture efficiency for 0.3 µm particles at 5 cm/s face velocity; ASTM method D-2986 Grade A-E I. W. Tremont Sterlitech Corporation 99.992% Capture efficiency for 0.3 µm particles and 360 Pa pressure drop at 5 cm/s face velocity; ASTM method D-2986 Grade E I. W. Tremont Sterlitech Corporation 99.98% Capture efficiency for 0.3 µm particles at 5 cm/s face velocity; ASTM method D-2986 Grade 934AH* I. W. Tremont Sterlitech Corporation 99.98% Capture efficiency for 0.3 µm particles at 5 cm/s face velocity; ASTM method D-2986 Pall 61631 A/E Glass Fiber Filter Pall Corporation, Port Washington, NY, US Data Support Company 2 Panorama City, CA, US 99.98% Aerosol retention; 70 kPa pressure drop at face velocity of 1000 cm/s Glass Microfiber Filter MGA Sartorius Stedim Biotech, Aubagne, France Sartorius Corporation 3 Bohemia, NY, US > 99.999% Capture efficiency of 0.3 µm particles method EN 143 Grade 934AH Whatman, GE Healthcare, Buckinghamshire, UK Tisch Scientific 4 Cleves, OH, US Typical particle retention in liquid of 1.5 micron Grade GF/A Whatman, GE Healthcare Tisch Scientific Typical particle retention in liquid of 1.5 micron 1. https://www.sterlitech.com/glass-fiber-filter.html 2. https://www.dscbalances.com/products 3. https://shop.sartorius.com/us/c/lab-filtration-purification 4. https://tisch-env.com/filters * 934-AH is a trademark of Whatman plc; rights acquired by GE Healthcare UK; now owned by Cytiva Life Sciences (Marlborough, MA, US), part of the Danaher Corporation (Washington, DC, US). Table 2 Glass-Fiber Filter Discs Tested (Alphabetical by Manufacturer)