Primarily for general aviation discussion, but other aviation topics are also welcome.
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By Sooty25
Paul_Sengupta wrote:
Sooty25 wrote:Do not use oxygen sourced from welding suppliers, it is not pure enough to breath and the impurities will harm you.

See Peter's comment on it here:

A lot of stories go around in aviation about "aviation oxygen" being of better quality than welding oxygen. Nobody to my knowledge has been able to find any substance to this. I telephoned a technical contact in British Oxygen Company (BOC); they sell oxygen in four grades


All have the same purity specification of 99.6%. The typical actual figure is 99.8%. The only thing that differs is the paperwork and the price. Even the old story that aviation oxygen is more dry (which would make sense) is untrue; the manufacturing process is the same but the QA does differ in that with aviation oxygen there is a limit on the permitted water content. So aviation oxygen might be more dry than welding oxygen but normally it is the same stuff.

In the years I spent working in the commercial diving industry, "welding" oxygen was never allowed on any job site. Cutting torches, when used, would be run on the diving oxygen.
Impurities were what was always quoted back then, but maybe it was just a paperwork exercise, maybe it wasn't. The question is, would you feed welding gas to your pax on the say so of some un-named contact of "Peter on the internet"?
0.4% impurity might not sound much, but you don't want it to be the wrong 0.4%.