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Method to Determine the Efficiency of Hepa And Ulpa Filters

IP.com Disclosure Number: IPCOM000062018D
Original Publication Date: 1986-Sep-01
Included in the Prior Art Database: 2005-Mar-09
Document File: 1 page(s) / 8K

Publishing Venue

IBM

Related People

Graham, GR: AUTHOR

Abstract

High efficiency particulate air (HEPA) and ultra-high efficiency particulate air (ULPA) filters are typically tested for filtering efficiency using the DOP Test. A light scattering technique counts the number of dioctyl phthalate (DOP) particles entering and emerging from the test filter. Dioctyl phthalate is a pale, viscous liquid plasticizer. DOP is placed in a pressure pot and then aerosolized for the DOP Test.

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Method to Determine the Efficiency of Hepa And Ulpa Filters

High efficiency particulate air (HEPA) and ultra-high efficiency particulate air (ULPA) filters are typically tested for filtering efficiency using the DOP Test. A light scattering technique counts the number of dioctyl phthalate (DOP) particles entering and emerging from the test filter. Dioctyl phthalate is a pale, viscous liquid plasticizer. DOP is placed in a pressure pot and then aerosolized for the DOP Test.

An alternative to DOP particles is perfluorinated polyether. This chemical is a clear, viscous lubricant which when made into an aerosol has a very tight size distribution. Eighty-five percent of the perfluorinated polyether falls between 0.1 and 0.3 microns in diameter. Only 36.7% of DOP particles fall into that region. DOP particles have a mean size of approximately 0.3 microns, while the perfluorinated polyether has a mean size of approximately 0.2 microns. HEPA filters have their lowest efficiency for particles between 0.1 and 0.2 microns in diameter. Since this is the size of particles that is most prevalent in ambient air, it is advantageous to test filter efficiency with a challenge aerosol that has a large concentration of particles in that region. Perfluorinated polyether generates large quantities of particles between 0.1 and 0.2 microns while DOP generates a relatively small amount.

Disclosed anonymously.

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