Good info about evacuating.Â* Only idiots would leave a bottle open to
the environment, but the world does seem to be populated by them in
increasing numbers.Â* I keep my bottle closed and blow out the trans fill
hose with O2 before closing the system to fill the aircraft bottle.Â* In
my original post I only mentioned medical oxygen because that was the
only supplier in town.Â* Locally, I simply go to the gas supplier and get
"oxygen".Â* I own my bottle but rather than hang on to it for 5 years and
then get a hydrostatic test, I just swap it out for another bottle.

On 11/10/2019 3:32 PM, wrote:
Oxygen is Oxygen. There is no difference between aviation and commercial welding oxygen except for liability insurance.
For a given tank, there is likely no physical difference, but the fill procedure appears different.
For welding, just fill is ok.
For medical and PBO, evacuate first is required.

If the previous user left the tank open for a while, there is a small chance of moisture but probably nothing else harmful.

I can get a big tank of pbo for a month from the welding shop for $35. The problem is I have to give them a week's notice so they will have it. And I can't go to a random Tractor Supply to get it.

For me, the extra hassle is worth not having to think about such an easily avoided 'probably'.






--
Dan, 5J