The purpose of this document is to present test methods that can be utilized to evaluate the filtration and operating characteristics of filters that will be utilized in a cryogenic system. The methods presented herein are intended to supplement standard filter testing specifications to allow evaluation of filter performance characteristics in areas that could be affected by extreme low temperatures. The test methods can be utilized to evaluate filters for particle sizes equal to or greater than 5.0 μm and flows up to and including 60 gpm (230 L/min) capacity. If higher flow rate filters are to be evaluated in accordance with the test methods presented herein, it will be necessary to increase the system flow capacity and the size of effluent sampling system from those recommended in this document.
The test methods presented herein do not encompass testing of cryogenic bypass relief valves, differential pressure indicators, gages, or components other than a basic filter housing and element.
This document is revised to clarify the limitations of the test methodology for cryogenic filters with respect to the detectable particle size limit. Additionally, equipment system accuracy requirements have been clarified, unit conversions provided and external references have been updated to current releases and practices.