CSA ANSI Z21.22-99/CSA 4.4-M99 (R2014)

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1.1

Scope

1.1.1

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 supp ly 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.

1.1.2

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.

1.1.3

A vacuum relief valve shall be of a single-purpose type.

1.1.4

All references to psi throughout this standard are to be considered gage pressures unless otherwise specified.

1.1.5

Exhibit A contains provisions that are unique to Canada.