312.55. Compressor: Every low pressure compressor must
(1) operate automatically and discharge the breathing mixture in an air cylinder having a sufficient volume to avoid excessive pressure variations;
(2) supply and maintain a breathing mixture supply corresponding to twice the required air flow, at a pressure 25% greater than the maximum pressure required;
(3) have a purification system that complies with Annex D to Standard CAN3 Z180.1 M85, Compressed Breathing Air and Systems; and
(4) be used with cylinders, devices and fittings that comply with CSA Standard CSA B51-M1991, Boiler, Pressure Vessel and Piping Code.
A high pressure compressor, 6.9 MPa or more, must not be used to directly supply a surface-supplied diver.