Thoughts on O2 clean

[jbd]

Someone recently queried,"Do you think welders give a @#$% about their tanks being O2 cleaned?"

I have the opprotunity to be in several welding shops each week and quite honestly there is so much stuff around ina welding shop that provides fuel and heat to go along with the O2 that it makes me wonder why they all don't blow sky high.

The end question was,"is the scuba industry just a little over anal about the O2 clean thing?"

[Rick Murchison]

Welding shops typically aren't filling anything with O2. They are taking O2 from a bottle and using it at ambient pressure to enhance the burn of something else. The welding shop never fills the bottle - it is the supplier who is concerned with the oxygen cleanliness of the bottle.
This is a far cry from taking oxygen from one bottle to another under high pressure.
No, we're not "too anal."
Anyone who thinks otherwise has never seen a fire in an oxygen enriched atmosphere.
Rick

[Cave Diver]

jbd once bubbled...
The end question was,"is the scuba industry just a little over anal about the O2 clean thing?"

No.

[BigJetDriver]

Rick Murchison once bubbled...
The welding shop never fills the bottle - it is the supplier who is concerned with the oxygen cleanliness of the bottle.
This is a far cry from taking oxygen from one bottle to another under high pressure.
No, we're not "too anal."
Anyone who thinks otherwise has never seen a fire in an oxygen enriched atmosphere.
Rick

When I took my first gas blending class, I was lucky enough to get it from "Hyper-Dick" Rutkowski himself. He used the comment in class: "Remember, welders in Mississippi survive using pure O2!"

This was not a slam on welders, because he went on to talk about how their O2 gear survives in the mud, oil, rust, and so on that they have to work in. As his lecture went on, it became obvious that he was very fanatical about cleanliness and materiels used in the blending side of things. Dick was striving to make the point that you don't have to FEAR the use of O2, but you do have to use some common sense.

As Rick pointed out, when you get to pouring those little O2 molecules at high pressure from one vessel to another, you had best be very, very careful!;)

[pt40fathoms]

Big difference here. Welders are taking O2 under high pressure and reducing it to ambient pressures. We on the other hand are filling a cylinder with O2, raising the pressure of the O2 to a level that we need to satisfy our end goal. (Nitrox, Trimix or Heliox) In the process of filling, heat is generated by the compression of the gas. The smallest contaminant in any part that comes in contact with the Oxygen being compressed, may ignite in the pure O2 environment. The resulting fire is amazing to watch, and very hard to stop. Not to mention the damage cause by a fire aided by the pure O2 environment.

The only way to get around using O2 clean bottles is to pre-mix the solution, then compress it. Remembering of course that any solution containing 50% O2 and higher are just as dangerous as 100% O2. Most pre-mix solutions would tend to be in the 32% range, and most well maintained “dry” compressors will be able to compress this gas with no problem. Do it yourselfer’s beware though, if you try to do this on the cheap. All you may end up with is several big bangs. If you survive.