This European Standard specifies minimum requirements for demand surface supplied and demand surface oriented diving apparatus to ensure a minimum level of safe operation of the apparatus. It applies to the following: - depths between 0 m and 50 m for apparatus using air, oxygen or oxygen in nitrogen mixtures; - depths between 0 m and 60 m for apparatus using oxygen, oxygen and helium or oxygen, nitrogen and helium gas mixtures; - water temperatures between 4 °C and 34 °C or outside these temperatures as specified by the manufacturer.