This part of the Def Stan specifies the requirements for non-medicinal breathing oxygen procured or in-situ produced for life-support applications and provides reference methods of test. It includes compressed gaseous breathing oxygen and liquid breathing oxygen procured / in-situ produced for aircraft and diving applications, breathing oxygen produced by MSOCS for aircraft oxygen systems, and breathing oxygen produced by low pressure electrolysers for marine applications on board HM ships and submarines.

• Medicinal breathing oxygen is excluded as it is covered by the European Pharmacopoeia monograph, however, where breathing oxygen 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.