This International Standard specifies test methods for evaluating the effect of hydraulic fluids on standard elastomeric materials that have been manufactured in accordance with specified processes. It allows baseline comparisons of fluids with standard elastomers. This International Standard provides formulations, mixing procedures and vulcanization procedures for five types of elastomeric composition: a) acrylonitrile-butadiene rubbers (NBR 1 and NBR 2); b) fluorocarbon rubber (FKM 2); c) ethylene propylene diene rubber (EPDM 1); d) hydrogenated acrylonitrile-butadiene rubber (HNBR 1). These procedures evaluate the effect of mineral-based, fire-resistant and biodegradable hydraulic fluids on such compositions by measurement, under controlled conditions, of physical properties of standard test pieces of the elastomer before and after immersion in the fluids. This International Standard does not provide formulations of elastomeric materials for actual service, although service elastomers may be tested using these compatibility procedures if required.