scope:

This part of the Def Stan specifies the requirements for non-medicinal compressed natural breathing air (CNBA) procured or in-situ produced for life-support applications and provides reference methods of test. It includes CNBA for aircraft applications, and marine /diving fire-fighting and emergency escape applications on board HM ships and submarines.

• Pure air, procured or in-situ produced specifically for specialised cooling applications (ie detector cooling), is excluded as this is not a breathing gas and its requirements are specified in Def Stan 58-96.

• Medicinal CNBA is excluded as it is covered by the European Pharmacopoeia monograph, however, where CNBA is to be used for therapeutic purposes at pressure, ie during recompression treatments and hyperbaric therapy, it 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.