teach me about refilling an oxygen tank

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JOhnH

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I have a 22 cu foot Aerox O2 tank.

I also have access to the H tanks with medical oxygen at the veterinary clinic I sold a few years ago.

I am considering asking the new owner if I could refill my portable from his H tank if I purchase an adapter, (and pay him an appropriate amount) but I'm not sure how good of an idea this would be.

Is it dangerous? Is there anything I need to be particularly cautious about? Are there variations in which adapter I might need? Would I need to use a full (or nearly full) H tank to assure adequate pressure?
 
I use a local o2 supplier that mostly supplies welding facilities, but also does medical. I put a deposit on a big bottle and bought the needed adapters. I can refill at my convenience. Costs me $30 for 10 - 15 refills, and they come to me and swap out with a full bottle for that price.
 
We get aviators breathing O2 from the welding supplier. Its not expensive to just get your own set-up if you have the space. You will be able to get full charges for a while but eventually would will need a booster to top off your portable. ASSuming your portable bottles are the same size as ours, I would take a WAG that you could top them to 1800psi ~15 times before a booster is needed. It would probably make more sense to just get a fresh O2 bottle at that point.
 
Tank will heat when filling, fill slowly.
Keep grease away from fittings.
CGA 540 fitting is a nipple and nut configuration for cylinders larger than an E size (i.e. M60, MM H, J, K & T).
CGA 870 is a fitting for oxygen only and is used for E cylinders and smaller.
what I used:
1-2 small o2 tanks for the plane (CGA870).
1-2 330 cu ft cylinders (CGA540) to use as supply to refill the small plane tanks.
a transfill adapter (CGA540 TO CGA870).
a couple regulators (CGA870) - i like the pulse 5 regulators (around $50 on ebay)
a couple nasal cannulas.

The CGA540 is the one typical on welding oxy bottles.
The CGA870 fits the small oxygen tanks which I carry in the plane.

Search ebay for Regulators:
EASY PULSE 5 6 OXYGEN REGULATOR


Transfill adapter:
Oxygen Transfill Transfiller Adaptor CGA540 CGA870 Veterinarian Aviation
 
And make sure your tanks are within their age limits for hydrostatic tests. When you take your takes to a commercial shop, they will check. When you fill yourself, you are responsible for that.
 
I had a long discussion with an engineer in the gases industry. He said all welding/Aviation/Medical oxygen is the same and has been the same for several years. The reason it's the same is economics. The industry uses the same liquid oxygen for all sources. For some distributors there may be a difference in welding verses aviation/medical cylinders as welding is not required for the same level of clean for the cylinder. However even welding Oxy in a welding cert cylinder is mostly the same since the same process is used for all to refill.

My local welding gas shop charges a very small uplift for guaranteed aviation oxygen so I buy that. After you buy your own 40 or 80 Cu ft set-up, the refill is cheap.

Other experts many have other views, just sharing what was shared with me from an engineer 30 years in the business.

The hydro static test and valve check is no joke. It's not expensive and worth performing on the 5 year recommended interval. Yes, 99% of the time it passes. If you're traveling X-country and need a refill many places will not recharge unless the bottle was stamped with a test date within 5 years.
 
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BTW this is what an exploding oxygen tank looks like:


Yes, the guy shot the tank to make it rupture.
 
I will reiterate forane’s warning about grease and add a couple more.

obviously people use these bottles all day everywhere so it’s not common....but please be aware high pressure O2 is no joke. The tank and valve/regulator need to be designed and fit for O2 service. The wrong rubber seal or valve design/material can cause a fire or explosion. O2 at high pressure is much more reactive and can be very dangerous. Read some info online regarding diving or aviation handling of it and pay attention.
 
I'd posted the text below in another thread, but it may be useful to repeat here:

There are a few things to know when home brewing an O2 system; properly cleaning any components that will see high-pressure O2 is particularly important. I'm a big fan of the (recently updated) Oxygen Hacker's Companion http://www.airspeedpress.com/newoxyhacker.html It's geared to technical divers, but chapters relevant for pilots include:

- How to O2 clean your gear (and is oxygen cleaning really necessary)?
- Legal issues. Do you need a prescription to buy/use O2? Is it legal to mix your own dive gas?
- Is welding O2 safe to breathe? The truth about O2 grades.
- Dealing with compressiblity in the real world
- How to assemble your own low cost dive emergency treatment or aviation O2 set.
- Dealing with gas suppliers - an insider's guide to buying oxygen and helium.
- Buy or rent your O2 storage tanks?
- Where to buy O2 tanks - medical and industrial - for half what your local gas dealer charges.
- How to get "orphan" medical and welding tanks filled.
- Why aluminum O2 tanks have green shoulders.
- Easy to make, no-machining SCUBA-to-NPT, NPT-to-SCUBA, and medical O2 adaptors.
- How to cut the cost of hydro testing in half.
 
Cleanliness is survival when messing with oxygen at anything other than slightly above atmospheric pressure. Understand the process and the rate of transfer to safely fill your bottles. Spend the money and buy a decent IR thermometer gun and USE IT... Pick a point near the neck of the bottle and use that as your target. When filling, you do not want a temp rise of more than about 15-20 degrees max from where the bottle was prior to starting the fill. Anything more than that, lower the supply pressure and let the tank equalize and the temp come down to within that range. Raise the fill pressure in 100-200 psig max increments, and let the tank equalize before upping the pressure. It's going to take a a half hour to 45 minutes to fill a bottle so be prepared.

Buy some isopropyl alcohol that is at least 91% and use clean, no lint cloth on fittings. Sped the money and get some 16OX-28 Leak-Tec or some 372E Leak-Tec to make sure you have no leaks on your valves or connections. The Leak-Tec is 10-20$ a bottle, but it will last your needs for probably 40-50 fills.

It's all the same process and materials that we use to fill our bailout and backup bottles for our ejection seats, and I still have to do a few LOX bottles for a couple of birds we have hanging around at work.
 
JOhnH said:
I have a 22 cu foot Aerox O2 tank.

I also have access to the H tanks with medical oxygen at the veterinary clinic I sold a few years ago.

I am considering asking the new owner if I could refill my portable from his H tank if I purchase an adapter, (and pay him an appropriate amount) but I'm not sure how good of an idea this would be.

Is it dangerous? Is there anything I need to be particularly cautious about? Are there variations in which adapter I might need? Would I need to use a full (or nearly full) H tank to assure adequate pressure?
Click to expand...

If you get the urge to stick your head out the window, get a refill somewhere else and don’t go back to the vet
 
NordicDave said:
BTW this is what an exploding oxygen tank looks like:


Yes, the guy shot the tank to make it rupture.
Click to expand...

allPrimes said:
Woah. Coulda been super bad.
Click to expand...

Several years ago a neighbor didn't need any of that hydro static testing sh*t (that was his attitude). His cylinder exploded and he lost an eye and a lower leg.
 
NordicDave said:
Several years ago a neighbor didn't need any of that hydro static testing sh*t (that was his attitude). His cylinder exploded and he lost an eye and a lower leg.
Click to expand...

That reminded me to check mine. It's due, I think. It's a 3AL which is five years except it is 10 if there is a star after the last date. This don't look like a star, but there are no other symbols that mean something that I know of. Anybody recognize that symbol and know if I have a 5 or a 10 year tank?

___IMG_0958.jpg
 
luvflyin said:
Anybody recognize that symbol and know if I have a 5 or a 10 year tank?

View attachment 89998
Click to expand...

I think hydro testing facilities commonly have their own symbol stamp, applied (along with the date) when a tank passes hydro.

My experience is mostly with SCUBA tanks, sometimes for high O2 mixes used for decompression...in that space, there are no 10 year tanks. All tanks are required to have a hydro every 5 years.
 
GaryM said:
I think hydro testing facilities commonly have their own symbol stamp, applied (along with the date) when a tank passes hydro.

My experience is mostly with SCUBA tanks, sometimes for high O2 mixes used for decompression...in that space, there are no 10 year tanks. All tanks are required to have a hydro every 5 years.
Click to expand...

This where I read where if there is a star, it's 10 years http://www.tymsinc.com/hydrostatic-faq.html
 
luvflyin said:
This where I read where if there is a star, it's 10 years http://www.tymsinc.com/hydrostatic-faq.html
Click to expand...

Sure enough. I wasn't aware of that, thanks.

One other bit of tank trivia that might be relevant...if your tank only has a DOT stamp, and not also a TC stamp (Transport Canada), you can't get it refilled in Canada. I learned that the hard way on my first tech diving trip into Canada, and my two big sets of doubles lacked the TC stamps.

Tanks will often have both stamps, and as far as I know it's legal to transport non-TC tanks into Canada, you just can't get them filled there.
 
Jeff Oslick said:
And make sure your tanks are within their age limits for hydrostatic tests. When you take your takes to a commercial shop, they will check. When you fill yourself, you are responsible for that.
Click to expand...
My portable is new(ish) and the veterinary hospital leases their tanks from Airgas. They get swapped out fairly often so I assume they are inspected. But I'll be sure to keep an eye on that in the future.
 
GaryM said:
Sure enough. I wasn't aware of that, thanks.

One other bit of tank trivia that might be relevant...if your tank only has a DOT stamp, and not also a TC stamp (Transport Canada), you can't get it refilled in Canada. I learned that the hard way on my first tech diving trip into Canada, and my two big sets of doubles lacked the TC stamps.

Tanks will often have both stamps, and as far as I know it's legal to transport non-TC tanks into Canada, you just can't get them filled there.
Click to expand...
Turns out the 10 year thing is for 3AA's only. I have a 3AL so I have to do it. Thx for the info
 
JOhnH said:
My portable is new(ish) and the veterinary hospital leases their tanks from Airgas. They get swapped out fairly often so I assume they are inspected. But I'll be sure to keep an eye on that in the future.
Click to expand...
He's talking about having YOUR tank inspected on schedule.
 
Salty said:
He's talking about having YOUR tank inspected on schedule.
Click to expand...
Actually, that's what I meant too, but didn't say correctly. My tank is new, but now I know to keep an eye on it in the future. I'll put blind faith in Airgas that they will deliver inspected tanks.
But thanks for making that clear.
 
luvflyin said:
If you get the urge to stick your head out the window, get a refill somewhere else and don’t go back to the vet
Click to expand...
Same if you start walking around the FBO sniffing someone's butt.
 
JOhnH said:
I also have access to the H tanks with medical oxygen at the veterinary clinic
Is it dangerous? Is there anything I need to be particularly cautious about? Are there variations in which adapter I might need? Would I need to use a full (or nearly full) H tank to assure adequate pressure?
Click to expand...

John, I have done this (transfilling small bottles from vet clinic H cylinders) for 15 years or so.
(the chemical makeup of all common sources of O2 is identical now, the only difference paperwork- so I use “welding supply” O2.)
I transport O2 from source to airplane using two E cylinders.
Of course, a fuller source bottle is better than half-used ones, as is more than one source bottle vs only one.
The farther from 2000psi you start with, the shorter the O2 ‘range’ in the airplane
 
Let'sgoflying! said:
John, I have done this (transfilling small bottles from vet clinic H cylinders) for 15 years or so.
(the chemical makeup of all common sources of O2 is identical now, the only difference paperwork- so I use “welding supply” O2.)
I transport O2 from source to airplane using two E cylinders.
Of course, a fuller source bottle is better than half-used ones, as is more than one source bottle vs only one.
The farther from 2000psi you start with, the shorter the O2 ‘range’ in the airplane
Click to expand...
Thanks.

I think I have this figured out now.
The vet hospital has 3 tanks. They use one at a time. When one is empty they manually move the regulator that feeds the manifold to the rest of the hospital to another tank and order a replacement tank. Two tanks should be sufficient but over the years, there have been a few times, like a long holiday weekend where a couple of cats were in an oxygen chamber and a single spare wasn't enough and the 3rd tank was necessary, so they (almost) always have two full tanks on hand. I can always refill from one of them, and if I want to I can fill halfway from one and finish up from another full one. Taking 10 or 20 cu ft from a couple of tanks will only reduce their capacity by a few %.

Thanks for all the advice. The adapter will only cost me about the price of one paid refill and the ongoing oxygen cost will be negligible.
 
NordicDave said:
Thanks for posting this training video. Hopefully pilots who have been caviler about compressed oxygen cylinders will be moved to reconsider the importance of bottle and regulator testing on schedule.
Click to expand...
I've known about the dangers of O2. Treat the bottle with respect, NO SMOKING or other flames and have the bottle inspected periodically, according to code or manufacturer instructions.

But one thing I learned from this thread is that you have to go slowly when refilling. Go in steps and allow it to stabilize before proceeding.
 

Yes, the guy shot the tank to make it rupture.[/QUOTE]

That freaked me the F out. I'm overdue. I disconnected the hose, opened the valve and let the gas out. Going today to get it tested and refilled. Yeah, I know the guy shot it and I'm not all that overdue and yeah the odds of mine blowing are just about nil.

EDIT: Agghhh!! Then I looked at post #28
 
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luvflyin said:
I disconnected the hose, opened the valve and let the gas out.
Click to expand...
OK to let out most of the O2. But you don't want to let it go totally empty and you definitely don't want to let it sit with the valve open - air/moisture can get in and trigger corrosion.
 
luvflyin said:
To late, I emptied it. Did close the valve
Click to expand...
Sorry to question, but did you really think that if your tank was at half or less pressure that it had a chance of exploding just sitting there because it was a year or two past it’s government mandated test date? I mean it only really has a chance to burst if it is close to max pressure or has been damaged in some way. I have some old welding tanks where the first test date is back in the 1930s or earlier and they look like crap on the outside but still test fine.
 
Matthew Rogers said:
Sorry to question, but did you really think that if your tank was at half or less pressure that it had a chance of exploding just sitting there because it was a year or two past it’s government mandated test date? I mean it only really has a chance to burst if it is close to max pressure or has been damaged in some way. I have some old welding tanks where the first test date is back in the 1930s or earlier and they look like crap on the outside but still test fine.
Click to expand...

It was almost full. Yeah, I probably over reacted. Nah, I did over react.
 
FORANE said:
Tank will heat when filling, fill slowly.
Keep grease away from fittings.
CGA 540 fitting is a nipple and nut configuration for cylinders larger than an E size (i.e. M60, MM H, J, K & T).
CGA 870 is a fitting for oxygen only and is used for E cylinders and smaller.
what I used:
1-2 small o2 tanks for the plane (CGA870).
1-2 330 cu ft cylinders (CGA540) to use as supply to refill the small plane tanks.
a transfill adapter (CGA540 TO CGA870).
a couple regulators (CGA870) - i like the pulse 5 regulators (around $50 on ebay)
a couple nasal cannulas.

The CGA540 is the one typical on welding oxy bottles.
The CGA870 fits the small oxygen tanks which I carry in the plane.

Search ebay for Regulators:
EASY PULSE 5 6 OXYGEN REGULATOR


Transfill adapter:
Oxygen Transfill Transfiller Adaptor CGA540 CGA870 Veterinarian Aviation
Click to expand...

FORANE, thanks for the good info. I ordered a size D cylinder with a CGA-870 valve and am looking at eBay for an Easy Pulse 5. I have a couple of questions:
  • Have you had any issues above 10,000’ with the regulator? I saw the manual mentions only up to 10,000’, just wondering if and how it might behave different between 10k and 18k.
  • How good are those 5 pulse settings for dialing in? Not having used one before I’m wondering if the adjustment is fine enough?
  • Have you tried OxySaver cannulas with that regulator? I assume they are not compatible, but I saw someone else posted that they had luck with another on-demand regulator and conserving cannulas working with it.
  • What about splitting for two? I take it you use a second regulator or do you use the Easy Pulse 5+6 and dial in a continuous setting?
Thanks!
 
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  • Have you had any issues above 10,000’ with the regulator? I saw the manual mentions only up to 10,000’, just wondering if and how it might behave different between 10k and 18k. I have used mine to 17.5 with no issues.
  • How good are those 5 pulse settings for dialing in? Not having used one before I’m wondering if the adjustment is fine enough? I typically use the pulse setting and it works great for me. I guide adequate supply by spo2 levels.
  • Have you tried OxySaver cannulas with that regulator? I assume they are not compatible, but I saw someone else posted that they had luck with another on-demand regulator and conserving cannulas working with it. I have not tried those cannulas. If you use the pulse setting, that type cannula likely has little or no benefit.
  • What about splitting for two? I take it you use a second regulator or do you use the Easy Pulse 5+6 and dial in a continuous setting? I keep 2 tanks in the plane. One tank per person in a 2 seat plane. I think I have M-6 cylinders.
 
Last edited:
FORANE said:
  • Have you had any issues above 10,000’ with the regulator? I saw the manual mentions only up to 10,000’, just wondering if and how it might behave different between 10k and 18k. I have used mine to 17.5 with no issues.
  • How good are those 5 pulse settings for dialing in? Not having used one before I’m wondering if the adjustment is fine enough? I typically use the pulse setting and it works great for me. I guide adequate supply by spo2 levels.
  • Have you tried OxySaver cannulas with that regulator? I assume they are not compatible, but I saw someone else posted that they had luck with another on-demand regulator and conserving cannulas working with it. I have not tried those cannulas. If you use the pulse setting, that type cannula likely has little or no benefit.
  • What about splitting for two? I take it you use a second regulator or do you use the Easy Pulse 5+6 and dial in a continuous setting? I keep 2 tanks in the plane. One tank per person in a 2 seat plane. I think I have M-6 cylinders.
Click to expand...

Much appreciated, thanks! I’ll get a basic cannula and will probably also aim for a second tank setup when I fly with someone else. I have a pulse oximeter as well for spo2 levels.
 
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