CFR /  Title 46  /  Part 64  /  Sec. 64.65 Vacuum relief device.

(a) Each MPT that is designed for an external pressure of less than 7.5 psig must have a vacuum relief device.

(b) A vacuum relief device for an MPT must--

(1) Open at an external pressure of not less than 3 psig; and

(2) Have an opening with a cross-section of 0.44 square inch or more. [CGD 84-043, 55 FR 37410, Sept. 11, 1990]