ISO/TR 4813:2021

Hydraulic fluid power — Background, impact and use of ISO 11171:2020 on particle count and filter test data

This document provides the background for ISO 11171:2020 and the use of μm(c) as the sole means of reporting particle size for APC particle count data. It also summarizes results of the international inter-laboratory study (ILS) of its reproducibility using SRM 2806d candidate material and suspensions of Reference Material (RM) 8632a. The ILS results provided the basis for certification of SRM 2806d used for primary calibration of APC. Their implications with respect to particle counting and filter testing are discussed in this document.