(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) FrangibleRupture discsdisks of safetynon-reclosing ventspressure 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, appendixsee A,§ A5171.037 of this subchapter). (c) For safetypressure 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]