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