Section 64.59 - Spring loaded pressure relief valveA spring loaded pressure relief valve must-
(a) Be set at a nominal pressure of 125 percent of the maximum allowable working pressure;(b) Have a minimum normal venting capacity that is sufficient to prevent the tank pressure from exceeding 137.5 percent of the maximum allowable working pressure;(c) Close after discharge of a pressure not lower than 115 percent of the maximum allowable working pressure; and(d) If closed, remain closed at any pressure less than 115 percent of the maximum allowable working pressure.