Standards for pressure drop testing of filters as applied to HEPA filters

A study has been made of the pressure drop testing performed by three filter test facilities for the Department of Energy. The testing is performed for both pressure drop and filter efficiency to assure that the filters meet specifications for use in the nuclear industry. It is shown that serious errors in pressure drop testing can occur if mass flow rates are used without correcting the pressure drop to a standard condition. Several alternatives are given for testing methods, including use of volume flow rates or laminar flow meters as testing standards. Similar standards should be considered for general filter pressure drop testing