AS 1357.1:2019 Valves primarily for use in heated water systems
7.4  Springs
Springs governing the opening function of a temperature-relief valve shall have a smooth finish. Seals shall be non-adjustable. Packed glands shall not be used. In the case of valves incorporating a hot water delivery connection, the spring shall be protected against contact with the delivered water.
7.5.1  Selection of valves for type testing
Valves of each design and size shall be submitted for type testing, subject to the following:
(a) Tests on valves with the centre-line of the inlet connection horizontal render unnecessary the test with the centre-line vertical, but not vice versa.
(b) Valves with optional features, such as hot water take-off connections or extended inlet connections, are considered to be of the same design as the basic valve for the purpose of all tests other than Tests 1 and 3.
(c) For valves of different sizes that incorporate —
(i) identical easing gear design;
(ii) identical spring design for the same pressure setting; and
(iii) identical temperature probe design for temperature operation,Tests 2, 6 and 9 on one size of valve render unnecessary these tests on the other size of valve.
7.7.1  General
An auxiliary pressure relief device shall be fitted to the body on the discharge side of the valve and shall conform to the following:
(a) The centre-line of the device shall be not closer to the face of the valve seat than the centre-line of the drain connection.
(b) The device shall not discharge towards the easing gear.
(c) The device shall be of such design and construction that no part can be expelled during operation.
(d) When tested in accordance with Appendix H, the device operate to discharge water at temperatures of 20 ± 5 °C and 85 ± 5 °C within the following limits:
(i) Not less than 50 % of the set pressure of the valve to which it is fitted; or 500 kPa,whichever is the lesser pressure.
(ii) Not greater than 110 % of the set pressure of the valve to which it is fitted.