On Sunday, June 3, 2018 at 7:25:01 PM UTC-7, Charlie M. (UH & 002 owner/pilot) wrote:
No, I can't.
I go based on having Scott airpacks refilled for emergency use at manufacturing plants I have worked at in the past.
User manuals back then stated to refill with "breathing oxygen", thus my comment.
I thought part of that was humidity, but not sure.

If someone went to a decent supplier and asked for "breathing oxygen" and were told, "no difference", then fine.

Moisture differences in different labeled oxygen supplies (again we are talking about O2 from cryogenic fractional liquid distillation) is an old wives tale. There is no water vapor in the gases produced by fractional liquid distillation, and nobody is going to add any downstream to the high pressure gas. High pressure O2 is extremely reactive and the systems would not tolerate moisture in it. Imagine the rust/corrosion eating holes inside a steel cylinder in a pure oxygen high pressure environment with water condensed inside of it. Yes they nay have surface treatment, but its only partially effective. Humidity in medical oxygen is added to the oxygen at the point of administration when the oxygen is essentially at room pressure and the delivery system is all inert plastic and silicone.

There are risks in dealign with this stuff. Handling any high-pressure gas and such a powerful oxidizer as high-pressure oxygen is dangerous, I hope people minimize those risks, there have been had fires during transfilling and nice articles about that in Soaring Magazine in the past, luckily nobody was injured or killed. Personally I'm OK with breathing welding supply oxygen as long as I know the handlign has been reasonable. I have been more worried just seeing people handle cylinders with less than respect than they deserve.