This International Standard specifies the endurance test necessary to confirm the ability of hand-operated plastics valves to withstand prolonged use, with repeated opening and closure. It does not specify the ability of valves to withstand adverse conditions, in particular those of chemically aggressive fluid media and/or environments, or excessive fluid velocities and cavitation. NOTE For what concern the chemical aggression of the materials, a classification table is reported in ISO TR 10358[1]. This International Standard includes values of the parameters necessary for the proper performance of the endurance test, with the reservation that parameters may be different in particular product standards (see 5.1).