Section 179.300-17 - Tests of pressure relief devices(a) Each valve shall be tested by air or gas before being put into service. The valve shall open and be vapor-tight at the pressure prescribed in § 179.301 .(b) Rupture disks of non-reclosing pressure relief devices must be tested and qualified as prescribed in appendix A, Paragraph 5, of the AAR Manual of Standards and Recommended Practices, Section C-Part III, AAR Specifications for Tank Cars (IBR, see § 171.7 of this subchapter).(c) For pressure relief devices of the fusible plug type, a sample of the plug used shall function at the temperatures prescribed in § 179.300-15 .(d) The start-to-discharge and vapor-tight pressures shall not be affected by any auxiliary closure or other combination.29 FR 18995, Dec. 29, 1964. Redesignated at 32 FR 5606, Apr. 5, 1967, and amended by Amdt. 179-10, 36 FR 21355, Nov. 6, 1971; 66 FR 45390 , Aug. 28, 2001; 68 FR 48572 , Aug. 14, 2003; 68 FR 75763 , Dec. 31, 2003