Nitrox Blending Rental of Air Cyclinders

[tomfcrist]

Regulations and standards exist for reasons. Which clearly leaves you in the enviable position of recommending others disregard those regulations.

Regulations? DAN, Praxair, the U.S. Govt nor anyone else regulates diving. OSHA regulates Commercial and scientific diving.

 

[BRT]

I have seen trace hydrocarbons in more than one welding gas supply. I'll see if my friend still has the quality reports. His shop was contracted out for some aerospace stuff. Their oxygen bottles were contaminated. It ended up costing them a bunch of money. If I can get them I'll post them here.

The Praxair and Arigas shops that I used to get welding bottles from had an entirely different O2 supply for med and av gas.

Again, why risk putting contaminated O2 into a tank you're going to be breathing from, whether partial pressure or through a compressor, potentially causing flashing and carbon monoxide build up that can overwhelm a filter stack introducing CO into a tank. There's a reason that there are purity standards when it comes to medical O2 and Aviator O2 for a reason. The fact that some people have gotten by makes no difference. 60 fpm ascents used to be recommended too, and a bunch of people never had a problem....still not a great idea.

If there are any hydrocarbons in an oxygen tank at 2200psi I'm pretty confident they will become CO2 in a flash, so to speak.

 

[sealark]

Aviators o2 is what most shops use and myself have been using for 20 years. The oxygen comes from the same tank for all the fills the difference is the aviators or bottles get evacuated every time before a fill. The industrial dont and there is a slight chance acetylene of other gasses could contaminate the industrial fills. There is no prescription required for avaitors O2. And it cost only a fraction more than industrial. I partial pressure fill my tanks. 450 psi of O2 into a 3200 psi bottle. Topped off with air should give you 32% nitrox. Make sure you get an analyzer.

 

[BRT]

Aviators o2 is what most shops use and myself have been using for 20 years. The oxygen comes from the same tank for all the fills the difference is the aviators or bottles get evacuated every time before a fill. The industrial dont and there is a slight chance acetylene of other gasses could contaminate the industrial fills. There is no prescription required for avaitors O2. And it cost only a fraction more than industrial. I partial pressure fill my tanks. 450 psi of O2 into a 3200 psi bottle. Topped off with air should give you 32% nitrox. Make sure you get an analyzer.

If you can keep acetylene in the same tank as oxygen why are we always worried about O2 clean tanks when partial pressure blending? I guess you could get Argon but if you get much your mix is going to be off. But acetylene is the gas that is hooked in tandem with the O2 cylinder and anytime the 2 mix under high pressure you get flames.

 

[sealark]

You dont keep aceteline in an O2 tank it gets cross contaminated when using a torch setup thats malfunctioning.

 

[tomfcrist]

That's what check valves are for.

 

[gfaith]

Questions: So Tom and sealark I guess you keep an O2 clean tank that you get filled with oxygen (aviator grade) for blending your enriched air? Do they evacuate your O2 cylinder before each fill?

 

[BRT]

You dont keep aceteline in an O2 tank it gets cross contaminated when using a torch setup thats malfunctioning.

You don't keep acetylene in an O2 tank because it would instantly burn and then it wouldn't be acetylene.

 

[Sevenrider860]

I get my O2 and Helium from a local supplier. They are cheaper than the larger distributors in my area (PraxAir, AirGas). I get "research grade" O2 and Helium. There is no prescription required. I do rent the cylinders for $8.95 a month.

 

[v101]

Thanks for the responses. So if I purchase some used oxygen cylinders, so I dont have to pay lease fees on them to the gas suppliers, are they usually good for refilling the bottles with oxygen?
Or do most rent their cylinders?