This document establishes methods to:
— validate equipment used to prepare secondary calibration suspensions for automatic particle counters;
— perform online secondary calibration of automatic particle counters;
— match two or more online particle counters, i.e. to count the same number of particles at a given size by two APCs associated on line;
— validate online particle counting systems with and without online dilution as used, for example, to measure the filtration efficiency of a hydraulic filter as described in the multipass filter test in ISO 16889.