This European Standard specifies minimum requirements for self-contained re-breathing diving apparatus to ensure a minimum level of safe operation of the apparatus. It applies to the following: - a maximum depth of 6 m for apparatus using pure oxygen; - a maximum depth of 40 m for apparatus using oxygen in nitrogen gas mixtures; - a maximum depth of 100 m for apparatus using oxygen and helium or oxygen, nitrogen and helium gas mixtures; - water temperatures between 4 °C and 34 °C. The requirements of this standard are intended to take account of the interaction between the wearer, the apparatus, and where possible the environment in which the apparatus is likely to be used. See annex ZA.