scope:

This part of the Def Stan specifies the requirements for non-medicinal breathing gas mixtures procured for marine / diving life-support and hyperbaric applications on board HM ships and submarines, and provides reference methods of test.

• These breathing gas mixtures are oxygen / helium mixtures (Heliox), oxygen / nitrogen mixtures (Nitrox) and oxygen / helium / nitrogen mixtures (Trimix).

• Medicinal breathing gas mixtures are excluded as they are covered by the European Pharmacopoeia monograph, however, where breathing gas mixtures are to be used for therapeutic purposes at pressure, ie. during recompression treatments and hyperbaric therapy, they should comply with the requirements of this part of the Def Stan.

• Reference methods of test are provided to give guidance on testing. They are not prescriptive, and alternative methods (AMs), which have been demonstrated in specific cases to DSFA's satisfaction to produce results adequate for the measurand, are acceptable.