CSA/AM - ANSI Z21.22-1999/CSA 4.4-M99
Relief Valves for Hot Water Supply Systems
|Publication Date:||1 April 1999|
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.