Is it worth the trouble and expense to carry emergency oxygen?

[Jonn]

I would not trust a 50 year old cylinder of O2.

Are you afraid of the cylinder rupturing mechanically, or the gas inside changing somehow?

 

[2airishuman]

Are you afraid of the cylinder rupturing mechanically, or the gas inside changing somehow?

- contamination from outgassing of seals and seats
- failure of service valve: leakage, jamming and failing to open, jamming and failing to close
- failure of relief valve (open or closed, both bad)
- contamination from particulate matter resulting from reaction with cylinder walls or materials knocked loose over many years of handling
- cylinder rupture due to sustained load stress cracking or corrosion

I think that periodic hydro tests are a good thing. The regulatory requirement that a cylinder only has to be in hydro at the time of filling is structured that way for practical reasons, not to encourage decades-long deployment of cylinders in standby service without inspection.

 

[mmerriman]

No it does not.
If its hasn't been used, you aren't obligated to use or empty it just because the hydro has expired. Just keep it in the box indefinitely

The Department of Transportation regulates hydrostatic testing in the Code of Federal Regulations (CFR), Chapter 49, Part 180.201 to 180.217. The Pipeline and Hazardous Materials Safety Administration (PHMSA) regulates the licensing of companies that perform cylinder requalification. A company that performs hydrostatic testing must be originally qualified by the DOT, and then be recertified every 5 years. PHMSA regulations also require that persons performing requalification of cylinders must receive specialized training and be certified. In addition, hydro-test personnel must be recertified every 3 years


Its the same thing with fire extinguishers. 5 years.

 

[mmerriman]

Not if you don't transport it in commerce or refill it. I don't even know when my last O2 cylinder hydro was. If I used it, I'd have to hydro it before I filled it again.

I know people think that if you don't transport a tank the DOT has nothing to say about it - but that 's not the case - even in place cylinder bank tanks require hydro testing. Realistically you're right - no need to hydro it until you empty it - BUT if I were operating commercially and had an accident - that expired hydro on my O2 tank or my fire extinguisher is one more thing the prosecution would use to show negligence. Interpret the regs any way you want - I'll be prudent.

 

[Wookie]

I know people think that if you don't transport a tank the DOT has nothing to say about it - but that 's not the case - even in place cylinder bank tanks require hydro testing. Realistically you're right - no need to hydro it until you empty it - BUT if I were operating commercially and had an accident - that expired hydro on my O2 tank or my fire extinguisher is one more thing the prosecution would use to show negligence. Interpret the regs any way you want - I'll be prudent.

No argument that the prudent thing to do is drain, hydro, and fill every 5 years. With fire extinguishers it's required (6 years for dry chem). Except when it's not. I had to buy a new Xintex yesterday, but before I did I spoke to Xintex. They told me that the requirement to hydro cylinders full of FE-241 is no longer in effect because you can't get FE-241 any more. So if you hydro the cylinders, you have to throw them away. So the requirement to hydro them is removed. I said "What?"

I'm not entirely sure that they know what they are talking about.

My boat has halon. I'm certainly not going to drain and hydro that cylinder. It's 15 years out of date.

 

[mmerriman]

No argument that the prudent thing to do is drain, hydro, and fill every 5 years. With fire extinguishers it's required (6 years for dry chem). Except when it's not. I had to buy a new Xintex yesterday, but before I did I spoke to Xintex. They told me that the requirement to hydro cylinders full of FE-241 is no longer in effect because you can't get FE-241 any more. So if you hydro the cylinders, you have to throw them away. So the requirement to hydro them is removed. I said "What?"

I'm not entirely sure that they know what they are talking about.

My boat has halon. I'm certainly not going to drain and hydro that cylinder. It's 15 years out of date.

i was referring more to CO2 systems, but you're right - all pressure vessels will have a requirement.

 

[rjack321]

From a regulatory standpoint this is correct. As long as the cylinder was in hydro when filled it is legal, at least under USA rules, for transportation.

At some point the question becomes whether you still trust the valve and the contents. I would not trust a 50 year old cylinder of O2. I don't think I would trust a 25 year old cylinder. I would like to be able to exchange cylinders (or drain inspect and refill) every few years because, at market rates, this is really just a matter of a few dollars and well worth it.

This is starting to sound like "O2 is a hassle and I'm not going to bother."

You won't live another 50 years. Carrying O2 with you in an expired cylinder for 7 or 8 years etc because you have to drive a long ways for a refill or whatever is not illegal or even uncommon.​

- contamination from outgassing of seals and seats
- failure of service valve: leakage, jamming and failing to open, jamming and failing to close
- failure of relief valve (open or closed, both bad)
- contamination from particulate matter resulting from reaction with cylinder walls or materials knocked loose over many years of handling
- cylinder rupture due to sustained load stress cracking or corrosion

I think that periodic hydro tests are a good thing. The regulatory requirement that a cylinder only has to be in hydro at the time of filling is structured that way for practical reasons, not to encourage decades-long deployment of cylinders in standby service without inspection.

The seals on medical O2 bottles are Teflon and viton. Neither are reactive and they are only going to be offgassing anything in a fire - which means you aren't breathing the contents anyway
CGA860 post valves can corrode and get locked closed. Keeping the cylinder dry will avoid this.
they use fusible lead plugs as relief ports which are not replacable and not part of hydrostatic service anyway
If you get water into your oxygen cylinder you have big problems
SLC is only applicable to 6351 cylinders. If your medical cylinder is post-1988 then SLC is irrelevant.

 

[mmerriman]

I get my medical bottle "filled" at a local gas supply shop. They will either take it and fill it which usually takes a week because they fill a bunch at once, or they'll trade it for a full bottle. when its out of hydro, that's a fast and cheaper way to go unless you have a place you can get a deal on hydro.

 

[2airishuman]

They told me that the requirement to hydro cylinders full of FE-241 is no longer in effect because you can't get FE-241 any more. So if you hydro the cylinders, you have to throw them away. So the requirement to hydro them is removed. I said "What?"

I'm not entirely sure that they know what they are talking about.

My boat has halon. I'm certainly not going to drain and hydro that cylinder. It's 15 years out of date.

There are places that pump out the halon, hydro the cylinder, and put the halon back in. I don't know what they actually use but it could be done with an automotive air conditioning service machine, cleaned and flushed with halon and devoted to that task, as a practical matter.

This is starting to sound like "O2 is a hassle and I'm not going to bother."

You won't live another 50 years. Carrying O2 with you in an expired cylinder for 7 or 8 years etc because you have to drive a long ways for a refill or whatever is not illegal or even uncommon.​

That's not where I'm going with this at all. I asked the questions in the OP because I don't, at present, have enough oxygen to deal with an emergency at some of the remote locations where I dive. I need to get more to cover that. I presently have an M6 cylinder (6 cf) which I keep with a regulator and mask attached, in a case, ready to go, and a size E cylinder which is 25 cubic feet and which (for shore diving) stays in the truck. I figure that's almost enough for an hour, for one diver. On the boat I don't think that's quite enough, and the E is a size that is awkward to store, so I'm trying to get 2-3 D cylinders (15 cf each, maybe a little more because they're steel) filled. That's where I am now and that's the presenting problem I'm trying to solve.

Someone else posed the "once and done so why do you need fills" and that has led to the additional discussion. Whether or not I'm diving in 50 years the point remains that oxygen cylinders really should be drained, inspected, hydro'ed, at refilled at some point. Perhaps not right away when the hydro is five years old, but at some point.

To the comment about valves and burst discs, with medical cylinders it is common to revalve them at hydro because the valves are cheap enough that doing so makes more sense than disassembling and inspecting the valve, and replacing the safety (burst disc).​

 

[tbone1004]

@2airishuman that's where the AL80 of O2 is much more useful and why I don't carry medical O2 bottles with me when I'm doing normal diving, despite owning several. You get 55cf of gas *without a booster, 75cf with* and you can always use the rescuean with nitrox which is better than nothing. Have you asked any local an/dp instructors what it would take for just the AN part? It's annoyingly a stupidly IMO a 2-day course, but if that's the only way to get scuba tanks filled with O2, then it is what it is.
Otherwise, are you sure there's no one in your area with a booster?