312.47. Auxiliary reserve: The auxiliary reserve referred to in subparagraph 2 of the second paragraph of section 312.46 must include,(1) for scuba diving, a complete diving breathing apparatus, including a half mask and a full cylinder, for each diver underwater;
(2) for surface-supply diving, a breathing mixture reserve equal to 2.5 times the required quantity to allow each diver to ascend and undergo decompression; and
(3) if a submersible compression chamber is used, a breathing mixture reserve that would allow the underwater work to be extended for 72 hours.