This document specifies a test method for the determination of the opening, closing and running torque of thermoplastics valves.

This document is applicable to all types of manually operable thermoplastics valves, with or without actuator, intended to be used for the transport of fluids.

NOTE 1？Examples of valve types tested with this method are in ISO？4437-4, ISO？16135, ISO？16136, ISO？16138, ISO？16139, ISO？16486-4, ISO？21787, EN？1555-4^[13] and EN？12201-4 ^[14].

This document does not specify the relationship between the torque and its possible increase after prolonged use of the valve under a specific working condition or wear/chemical aggression of the materials.

NOTE 2？Concerning the chemical aggression of the materials, a collection of data is reported in ISO/TR？10358 concerning the endurance test necessary to confirm the ability of hand-operated plastics valves to withstand prolonged use with repeated opening and closing operations. Further information is provided in ISO？8659.