This Standard applies to the following types of relief valves constructed entirely of new, unused parts and materials:
(a) Temperature relief valves and combination temperature and pressure relief valves for use on storage tanks of hot water supply systems without heater input limitation T&P valves, hereinafter called.
(b) Valves having only pressure relief features for use on storage tanks of hot water supply systems without heater input limitation.
(c) Vacuum relief valves.
A temperature relief valve, or a T&P valve shall operate when the temperature sensing element is at 210°F (99°C) or less. A device with a higher operating temperature is not acceptable under this Standard.
A vacuum relief valve shall be of a single-purpose type.
All references to psi throughout this standard are to be considered gage pressures unless otherwise specified.
Exhibit A contains provisions that are unique to Canada.
items 1 - of 2 result(s)
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ANSI Z21.22b-2001/CSA 4.4b-2001 (R2014) - Addenda 2 to ANSI Z21.22-1999/CSA 4.4-M99, Relief Valves for Hot Water Supply Systems
ANSI Z21.22a-2000/CSA 4.4a-2000 (R2014) - Addenda 1 to ANSI Z21.22-1999/CSA 4.4-M99, Relief Valves for Hot Water Supply Systems