Medical vs. Aviation Grade O2

[berk]

a good reference is the oxygen hacker from airspeed press.

the air grade is super dry air to prevent o2 line freezing from moisture in the gas on planes that have o2 lines on the skin of the plane. > 80% o2

med o2 is i think > 80% o2 and when filled the bottle is vacumm empty then filled to insure no contaminates.

welding o2 is 99.x% o2

all the gas comes out of the same storage tank. the filler may do some filtering on some of the lines for some of the fills.

the reall difference is the price.

med o2 $$$$$ needs a perscription to get
avation o2 $$ probably have to get at an airport
welding o2 - well 20 bucks for a tank refill from a gas supplier

i have no problem using welding o2.

i will soon make my own o2 from a concentrator and pump it into a 2200psi o2 tank

He uses welding o2. The better question might be, "what do you use and why."

I have only rented tanks once. I went for the ultra high purity HE and welding O2. I did have an account at the place and was a weekly buyer of propane for forklifts so no questions were asked to a familiar face.

-matt

 

[dannobee]

No difference, other than the paper trail.

If you think there could be more contaminants in welding bottles because welders are somehow "dirtier," or that the tanks aren't vacuumed out, guess who will be the first to know when it goes kaboom? The guy filling them at the industrial gas fill station.

From what I've personally seen, ALL of the tanks are treated exactly the same.

 

[NAM001]

As noted above the difference is in the bottle and the contaminants that may be in it. If you own your own bottles, then the evacuation of the cylinder is not really an issue. If you rent, or more importantly, exchange the cylinders, then it could be.

As noted above aviator O2 is required to be dry by the FAA, but I doubt it is in fact any drier than medical or industrial O2 - same source, same process, etc.

The major practical difference is that O2 suppliers will sell you aviator O2 no matter who you are, while in many states medical O2 requires a prescription.

i agree. it is my belief that one gas meets all the specs, just a varying liability issue for the filler depending on the use.

 

[NAM001]

i am not sure but is not our air supposed to have a dew point of -50 or so and the av O2 at -70 or so. the medical O2 is rehydrated as it is administered. supposedly when rehydrated it them becomes medical O2. begs the ?? why is it med O2 in the bottle MED O2.. and needs a script other than to declare the bottle is clean. kind of like having to pay extra at a diner to eat the same eggs but off a clean plate.

 

[swamp diver]

As noted above the difference is in the bottle and the contaminants that may be in it. If you own your own bottles, then the evacuation of the cylinder is not really an issue. If you rent, or more importantly, exchange the cylinders, then it could be.

As noted above aviator O2 is required to be dry by the FAA, but I doubt it is in fact any drier than medical or industrial O2 - same source, same process, etc.

The major practical difference is that O2 suppliers will sell you aviator O2 no matter who you are, while in many states medical O2 requires a prescription.

There are two grades of aviator's O2 available: commercial ABO (aviator breathing oxygen) and mil-spec.

I don't recall offhand what contaminant concentrations are verified for the ABO but it likely is not much different from USP (medical) where they analyze for CO and CO2. With ABO they would also verify the moisture content which usually straight off the production process will be in the ballpark of -65 F. This is the maximum moisture level permitted in the old CGA Grade E standard prior to the last revision.

Mil-spec O2 on the other hand is much drier than commercial ABO and is run through a desiccant bed after production to achieve the -81 F moisture specification. The list of contaminants analyzed for is long and as such this oxygen grade is much more expensive.

In fact the US and Canadian navies adopted the aviator's mil-spec standard for its Navy breathing oxygen standard which can be seen here in Table 4-3 Gaseous.
http://www.s297830378.onlinehome.us/usn/Chap04.pdf

Somewhere in the paperwork ABO has had its moisture content verified likely at the batch level.

 

[fire_diver]

i will soon make my own o2 from a concentrator and pump it into a 2200psi o2 tank

I hope you aren't planning on using a home-type medical oxygen concentrator. Those also have a high level of argon. At atmospheric pressure, it's not a problem. At diving pressure, it can very easily cause problems.

 

[Gilldiver]

Mil-spec O2 on the other hand is much drier than commercial ABO and is run through a desiccant bed after production to achieve the -81 F moisture specification. The list of contaminants analyzed for is long and as such this oxygen grade is much more expensive.

The only difference up to 5.0 gas AKA UHP or 99.9990% is what the gas is TESTED TO. You can never say that any gas up to this grade has more or less water/contaminate than another - it is only what tests that bottles fill lot was tested to and the paper trail that backs it up.

Major filling facilities (AIRGAS, PRAXAIR, BOC, etc.) will fill up to 10,000 bottles per day, usually in a batch of 6 or 12. How much care do you think they give each individual tank? If the computer at the fill station says they need 10 welding and 2 UHP's, a sample is drawn off of one of the tanks and sent through the GC and the fill operator scans 2 bar codes on the tanks in that lot. The cert is then created in the computer and down loaded at the sales store. The operator then prints out and puts the UHP stickers on the 2 tanks he scanned, the other 10 get the welding stickers.

A Major corp will get UHP O2 for $4 or less for 300 cubic feet, He at about $12-20. The gas packager makes their money on bottle rentals, delivery fees, haz mat fees, micky mouse fees, I stubbed my toe fees, ...................

 

[captain]

Having been an operator at a Praxair cryogenic air separation plant, all the oxygen produced was the same purity. Any significant deviation from purity would initiate an automatic diversion of gas to the atmosphere or shutdown of the plant.