This Standard sets out requirements for the design, construction, testing and performance of the following types of water valves of DN 15 minimum size:(a) Temperature/pressure relief valves.(b) Expansion control valves.(c) Non-return valves.The valves specified above (referred to in this Standard as valves) are specifically intended for use with unvented storage water heaters which are required to operate at temperatures-(i) not normally exceeding 85C; and(ii) under emergency conditions, not exceeding 99C.NOTES:1 For valves used with water heaters which are intended to operate at temperatures above 99C (e.g. hot water boilers), see AS 1271.2 The methods of test detailed in the Appendices determine the ability of the water valves specified herein to perform within specified limits of water temperature, pressure and non-return conditions for the protection of unvented storage water heaters.3 Instrumentation requirements are given in Appendix A.