Impact of changes in ISO fluid power particle counting - Contamination control and filter test standards

2Scope / Description

This technical report discusses the impact of changes in international standards for particle counting, contamination control, and filter testing. Automatic liquid particle counters (APCs) are used to monitor contamination levels in hydraulic fluids to establish cleanliness level specifications for components and assemblies, and to determine filter efficiency and particle size classes. Since the publication of ISO 4402 being superseded by ISO 11171 (APC calibration), ISO 4572 being superseded by ISO 16889 (multi-pass filter testing), and ISO 11943 (online particle counter calibration), the quality and reliability of particle counting and filter test data has improved, increasing their usefulness to industry. However, the resulting redefinition of particle size and the use of new test dusts have impacted the way contamination levels and filter performance are reported and interpreted. Note: The first editions of ISO 11171, ISO 16889, and ISO 11943 were all published in 1999; all three International Standards have either been revised or are in the process of being revised.