ISO 4021:1992

Hydraulic fluid power — Particulate contamination analysis — Extraction of fluid samples from lines of an operating system

The preferred method is to extract fluid samples from a main flowline in such a manner that the particulate contaminant in the sample is representative of the fluid flowing at the point of sampling. An alternative method is to extract a sample from the reservoir, but this method should only be used if a suitable sampler is not fitted.