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4.12.728    SAFETY DEVICES

(1)  Every pressure-vented container shall be provided with one or more safety pressure relief valves. The rate of discharge shall be in accordance with the provisions of Table E.

(2)  Container safety pressure relief valves shall be set to start-to-discharge at a pressure not to exceed 110 percent of the design pressure of the container.

(3)  Safety pressure relief valves shall be arranged so the possibility of tampering will be minimized. If the pressure setting adjustment is external, the relief valves shall be provided with means for sealing the adjustment.

(4)  Shutoff valves shall not be installed between the safety pressure relief valves or the vacuum relief valve and the container. A safety relief valve manifold which allows one valve of two, three, four, or more to be closed and the remaining valve(s)  will provide not less than the rate of discharge to allow the proper cubic feet per minute of air in relation to tank capacity as shown in Table A.

(5)  Each safety pressure relief valve and vacuum relief valve used shall be clearly and permanently marked as follows:

(a)  The relief setting.

(b)  The rate of discharge. (See Table E.)  

(c)  The manufacturer's name and identification number.

(6)  Connections for venting, such as couplings, flanges, nozzles, and discharge lines, to which relief valves are attached, shall have internal dimensions at least as large in diameter as the relief valve to avoid restriction of flow through the relief valves.

(7)  Discharge from safety pressure relief devices of permanent storage containers shall be directed in such a manner as to prevent any impingement of escaping gas.

History: Sec. 80-10-503, MCA; IMP, Sec. 80-10-503, MCA; NEW, 1986 MAR p. 1320, Eff. 10/31/86.

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