Canada Oil and Gas Diving Regulations (SOR/88-600)

22 (1) No diving contractor who conducts a diving operation shall conduct or permit the commencement or continuation of the diving operation unless

• (a) the total quantity of appropriate breathing mixture that is available at any time during the diving operation consists of

  • (i) an adequate quantity to complete the diving operation,

  • (ii) a reasonable quantity for a reserve supply, and

  • (iii) for use in an emergency, an additional supply that is

    • (A) in the case of a diving operation in which a diving bell is used, a sufficient quantity to meet the needs of the occupants of the diving bell for a minimum of 24 hours,

    • (B) in the case of a diving operation in which an ADS is used, a sufficient quantity to meet the needs of the occupants of the ADS for a minimum of 48 hours,

    • (C) in the case of a diving operation in which an on-line gas blender or diver’s gas recovery system is used, a sufficient quantity to allow the divers to continue, interrupt or discontinue the diving operation safely, and

    • (D) in the case of a diving operation in which a surface compression chamber is used, a quantity that is twice the amount required to pressurize the surface compression chamber to a pressure equivalent to the pressure at the greatest depth in respect of which the surface compression chamber will be used in the diving operation;

• (b) the purity of the breathing mixture is of an acceptable standard; and

• (c) the quantities referred to in subparagraphs (a)(ii) and (iii) are available for immediate use at a flow rate, temperature and pressure that are safe for the user.

(2) No diving contractor shall conduct a diving operation unless

• (a) any breathing mixture to be used in the diving operation is

  • (i) analysed for the accuracy of its oxygen content and, where practicable, its other contents immediately prior to the commencement of the dive that is part of the diving operation, and

  • (ii) supplied at temperature and humidity levels that are safe; and

• (b) the levels of oxygen and carbon dioxide in the breathing mixture to be used in the diving operation are maintained at levels that are suitable for the type, depth and duration of the diving operation.