Revisiting an old topic: Welding O2?

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This thread brings back some old and not so fond memories. I initially started trying to buy Medical Grade Oxygen for partial pressure blending about 12 years ago. Air Liquide would not sell it to me without a "prescription." Being an R.N. and EMT-Paramedic getting said prescription was easy. When I presented the prescrition to Air Liquide they then said "we are not pharmacists."
This was at the plant where air was actually cooled enough to get liquid Oxygen and Nitrogen. Thousands of cylinders were filled there everyday. Same manifold for every grade.
 
I just called my gas supplier (Roberts Oxygen) two weeks ago to gat a lease on two bottles of therapy grade 02. The sales guy asked me for what? I responded do I have to tell you? He said yes. I told him to blend scuba gas. He replied great!!, can I interest you in a lease on the biggest cascade that you can afford?
Maybe the economy is motivating them to sell, not be dicks.
obtw that line about building a space capsule was priceless!
Eric
 
It is my understanding that the only actual difference between welding oxygen and medical oxygen is that at the final delivery point the suck a vacuum on the bottle before filling it with medical oxygen. Same product, same cooling tower ... different delivery protocol.


FWIW, I am a Nitrox (<or= 40% O2) and Advanced Gas (>40% O2 and Trimix) Blending Instructor Trainer with TDI and hold the equivalent ratings at the instructor level with IANTD.

What I have always found to be the case with the vendors I have worked with is that Medical O2 cylinders are triple evacuated before filling and Industrial (welding) O2 cylinders are evacuated only once. Other than that they are the same gas as far as purity goes. Aviation O2 has a lower moisture content to prevent freezing in the delivery system at high altitudes. All O2 cylinders require the same level of cleanliness for obvious reasons.

Of course other vendors could have different methods and/or protocol for how they fill cylinders.

HTH
 
Usually I just ordered and the tanks arrived on the loading dock, we only bought medical grade for the ship, regardless of their intended purpose, so that in a diving emergency unused bottles were always available. My only direct experience with a vender's protocols is a surgical supply house, they evacuated the bottles and filled, and said that welding supply companies did not do that. Thanks for the information.
 
FWIW, I am a Nitrox (<or= 40% O2) and Advanced Gas (>40% O2 and Trimix) Blending Instructor Trainer with TDI and hold the equivalent ratings at the instructor level with IANTD.

Aviation O2 has a lower moisture content to prevent freezing in the delivery system at high altitudes. All O2 cylinders require the same level of cleanliness for obvious reasons.

TH

By the very nature of the process that produces oxygen the possibility of moisture in it is virtually impossible. Oxygen and most other atmospheric gases, nithogen and argon are produced in a cryogenic process that liquifies air to about -298 F.

All water vapor, carbon dioxide and carbon monoxide must be and are removed in molecular seive towers before the liquification temperature other wise the water and co2 would freeze and plug up the processing equipment. There is zero moisture in liquid oxygen so I cannot see how they can make the statement that aviators oxygen has less moisture.

The liquid oxygen is pumped at high pressure through an evaporator that turns it back into a gas and then to the cylinder filling rack.

Although there are other processes that can produce oxygen, liguification and fractional distillation is the only way to produce it at industrial volumn and economy. It is the process use by all the industral gas producers, Praxair, Air Liquide, Air Products, etc

I worked almost 30 years operating an air seperation plant for Praxair making 150 tons of oxygen a day. The unit would automaticly shutdown if moisture or co2 was detected downstram of the seive towers.
 
The lab guys at my gas supplier's plant told me that virtually all the O2 they sell meets aviation standards for dryness, except that every once in a while they get a tankfull that doesn't, and it always turns out to be one that was just hydroed.

By the very nature of the process that produces oxygen the possibility of moisture in it is virtually impossible. Oxygen and most other atmospheric gases, nithogen and argon are produced in a cryogenic process that liquifies air to about -298 F.
 
I use the avatiation grade. They would not sell me medical grade and I figured my life was worth a few extra bucks a tank over welding gas.

Isn't there a paper trail on the cylinders used for medical and aviation that is not present for welding gas?
 
The lab guys at my gas supplier's plant told me that virtually all the O2 they sell meets aviation standards for dryness, except that every once in a while they get a tankfull that doesn't, and it always turns out to be one that was just hydroed.

What type of tankful. Do they mean a tank truck of liquid o2 or an individual HP cylinder or bank of cylinders that they decant from.

Point being there is no difference in the way welding, aviation and medical o2 is manufactured. Any contaminants would have to come after the manufacturing process not during. Our specifications were zero h2o, 99.98% pure o2, the .02 percent was rare earth gases such as neon, xenon, argon, kypton, etc with argon being the greatest part of the .02%
 
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In fact, yesterday I gave Praxair a little pushback on their decision asking them to identify a "suit" at corporate that could give me a good reason NOT to sell gas to a certified blender/user. (I couldn't help it, I'm a lawyer).

I think may have changed their minds as I got a price quote this AM for O2 and He along with a message that my account is being set up....

Nonetheless, based on all of the responses thus far, my comfort level with welding O2 is as equally as "pure" - 99.95%.

Thanks.

I'm just curious, what price did you get?
 

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