SAE Standards Works
A-6C1 Contamination and Filtration Committee
AS4059F - Aerospace Fluid Power - Cleanliness Classification for Hydraulic Fluids
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Aerospace Fluid Power - Cleanliness Classification for Hydraulic Fluids
This SAE Aerospace Standard (AS) defines cleanliness classes for particulate contamination of hydraulic fluids and includes methods of reporting related data (Appendix A). The contamination classes selected are an extension ofbased on the widely accepted NAS 1638 cleanliness classes. Conversion from NAS 1638 cleanliness class specifications to AS4059 class specifications is defined. Comparison of the NAS 1638 classes to AS4059 classes is defined and the differences explained (Appendix B). This document provides versatility in identifying a maximum class in multiple size ranges, total number of particles larger than a specific size or designating a class for each size. NAS 1638 classes based on weight of particles are not applicable to either of these classes and are not included.
AS4059A served as the basis for ISO 11218 and was adopted by the coversheet method. ISO 11218 was never updated to account for AS4059 revisions B-E. There are changes requested by the international community to make AQS4059 acceptable for an ISO 11218 revision.