Ed Pawlowski wrote:

"Pete C." wrote

You're stuck on old paranoia based on information that is decades out of
date. All of the O2 purity grades specify no more than 0.05% impurities,
and the most lax of the standards is the medical / aviator grade. The
reality is that all the grades are filled from the same cryo O2 source
and all are better than 99.99% pure O2.

I know how a medical tank was handled. I don't know anything abut a welding
tank. The oxygen may be pure going in, but I don't know what was in the
tank beforehand.

The gas suppliers are not about to fill 2,000 PSI+ of pure O2 on top of
some amount of unknown gas in the welding tank, that would be dangerous
for them.


I'm not stuck on decades information, my son owns a medical supply company
that supplies oxygen. I worked part time for him filling tanks and
delivering LOX. We followed the regulations on medical oxygen. You are
free to breath whatever you like though.

You follow your insurance / liability regulations, which do not in any
way relate to the actual safety of using the "welding" O2 vs. "medical"
O2, and have not been updated in decades.