A compressor used to supply breathing air to a diver must have—

1. (a) A volume tank that is—

   1. (1) Built and stamped in accordance with section VIII, division 1 of the ASME Code with—

      1. (i) A check valve on the inlet side;
      2. (ii) A pressure gage;
      3. (iii) A relief valve; and
      4. (iv) A drain valve; and
   2. (2) Tested after every repair, modification, or alteration to the pressure boundaries as required by § 197.462;
2. (b) Intakes that are located away from areas containing exhaust fumes of internal combustion engines or other hazardous contaminants;
3. (c) An efficient filtration system; and
4. (d) Slow-opening shut-off valves when the maximum allowable working pressure of the system exceeds 500 psig.