This SAE Aerospace Recommended Practice (ARP) establishes a method for evaluating the particulate matter extracted from the working fluid of a hydraulic system or component using a membrane. The amount of particulate matter deposited on the membrane due to filtering a given quantity of fluid is visually compared against a standard membrane in order to provide an indication of the cleanliness level of the fluid. A particular feature of this method is the membrane preparation to achieve an even particulate distribution on the membrane suitable for other applications. Membrane evaluation using standard membranes, described in this document, is an alternative technique to counting with either an optical microscope (ARP598) or an automatic particle counter (ISO 11500). The latter particle counting procedures are considered more precise.
SAE ARP4285-2008 history
2018SAE ARP4285A-2018 Aerospace - Evaluation of Particulate Contamination in Hydraulic Fluid - Membrane Procedure
2008SAE ARP4285-2008 Aerospace - Evaluation of Particulate Contamination in Hydraulic Fluid - Membrane Procedure
2001SAE ARP4285-2001 Aerospace - Evaluation of Particulate Contamination in Hydraulic Fluid - Membrane Procedure