American Petroleum Institute (API) and The Institute of Petroleum, London (IP). February 2001. 50p. ISBN: 0 85293 282
0. This publication specifies the minimum requirements for a filter/separator system to qualify to API/IP 1581 by similarity.
This publication applies to two-stage (filter and separator) and the filter/separator stages of multi-stage filter/separator systems. This publication does not apply to monitor and/or prefilter stages that may be present in multi-stage systems.