Actual lifetime of AL O2 bottles

[TimRF79]

Thinking of getting a (portable) Oxygen system.
Debating between AL and Carbon bottles.
I know Carbon bottles have a 15yr limited life, but how long do AL bottles last in reality?

 

[GaryM]

Speaking from my experience with SCUBA tanks, aluminum bottles used for decompression mix (typically 80% or 100% oxygen) can be used as long as they pass the annual visual inspection and the hydro test every five years. I think some of mine are over 20 years old.

I don’t think aviation tanks have the annual inspection requirement, just the hydro test requirement

 

[aterry1067]

Speaking from my experience with SCUBA tanks, aluminum bottles used for decompression mix (typically 80% or 100% oxygen) can be used as long as they pass the annual visual inspection and the hydro test every five years. I think some of mine are over 20 years old.

I don’t think aviation tanks have the annual inspection requirement, just the hydro test requirement

Same. I think I have rented some AL Nitrox scuba tanks that may have been bought used from Jacques Cousteau's early voyages.

 

[crashton]

The Aluminum cylinders have an unlimited life, but both Kevlar and AL need to be hydrostatically tested before refilling if the last hydro is more than five years prior.

 

[Initial Fix]

Most aluminum cylinders will last many decades if well maintained. I say most as there was a number made in the 80s with a different aluminum mix that had cracking issues, but Those should all be out of circulation now.

 

[WDD]

You might find a wait list for an O2 system / SkyOx is back ordered to June. There is apparently a bottle shortage. I had to order the cannulas and regulator by themselves and source a welding O2 bottle off of Amazon.

“Medical” O2 bottles are harder to find.

 

[Bell206]

I don’t think aviation tanks have the annual inspection requirement, just the hydro test requirement

FYI: Technically there is no FAA requirements as the DOT regulates all pressurized containers, cylinders, etc. and the FAA defers all to them under Title 49 CFR. So any regulatory requirements for pressurized cylinders carried/used on aircraft will be found there as to inspection testing/life limits which depend on cylinder type.

 

[Checkout_my_Six]

these tanks are regulated by DOT....and there are life limits to aviation tanks....regardless of the material. My 115 CUFT tank has a 24 year life.

 

[crashton]

You might find a wait list for an O2 system / SkyOx is back ordered to June. There is apparently a bottle shortage. I had to order the cannulas and regulator by themselves and source a welding O2 bottle off of Amazon.

“Medical” O2 bottles are harder to find.

We have some systems in stock - PM me and I can tell you what we have...Yes, cylinders are very hard to come by. We are being quote 36 weeks right now on cylinders, but hopefully getting better in the next month or two.

Scott

 

[bflynn]

FYI: Technically there is no FAA requirements

the regulation is going to come from the fill shop. None of them are going to fill a tank that has an expired hydro, it’s a safety risk. It could explode on them as they fill it.

If they do, I would shy away because they don’t know their business.

 

[Bell206]

the regulation is going to come from the fill shop.

Possibly. But I was answering the "aviation side" of the requirement statement which there is none in the FARs for Part 91 aircraft. So if you throw an oxygen bottle or fire extinguisher in your aircraft and fly away the FAA defers to the pilot knowing what the test/life requirements are for those cylinders per DOT.

 

[Checkout_my_Six]

For an installed system....the filler isn't going to know the status of the bottle.

the regulation is going to come from the fill shop. None of them are going to fill a tank that has an expired hydro, it’s a safety risk. It could explode on them as they fill it.

If they do, I would shy away because they don’t know their business.

the regulation is going to come from the fill shop. None of them are going to fill a tank that has an expired hydro, it’s a safety risk. It could explode on them as they fill it.

If they do, I would shy away because they don’t know their business.

 

[bflynn]

For an installed system....the filler isn't going to know the status of the bottle.

Ok. But if you have an installed system and you aren't getting it checked, you're the one carrying around the potential bomb.

 

[Checkout_my_Six]

Yup....So, it comes down to the "operator" being responsible. I'd also think that it's something to be checked during the annual.

Ok. But if you have an installed system and you aren't getting it checked, you're the one carrying around the potential bomb.

 

[Bell206]

I'd also think that it's something to be checked during the annual.

It should be, but its not in all cases unless the annual is performed per an OEM recommended program/list. Then there usually is a line item to check the test dates for a possible oxygen cylinder, fire extinguisher, etc. Or if the aircraft had an Airworthiness Limitations Section you may find the life limits of those items listed like they do with float bottles on helicopters. Part 43 Appx D doesn't call out for any date check of pressurized cylinders. Unfortunately, in cases where there isn't a track record of checking the test/life dates on those cylinders they usually only get noticed during a conformity check or prebuy or after a failure with fire extinguishers leading that list. I wonder how many on PoA know the hydrostatic date on their fire extinguisher? 91K, 135, 121 all have requirements for an inspection program to cover extinguishers, oxy bottles, etc. so its rare that you see it missed at that level.

 

[GaryM]

these tanks are regulated by DOT....and there are life limits to aviation tanks....regardless of the material. My 115 CUFT tank has a 24 year life.

View attachment 104397

That table, and the link at the bottom of that table, make no reference to life limits for Al tanks, only for steel and composite/kevlar. The link does mention that Al cylinders are "For Portable Use Only or for Permanent Installation in Non-Factory Aircraft", but no life limit is given.

 

[Checkout_my_Six]

Correct....many of the smaller diameter "portable" tanks are not life limited.

That table, and the link at the bottom of that table, make no reference to life limits for Al tanks, only for steel and composite/kevlar. The link does mention that Al cylinders are "For Portable Use Only or for Permanent Installation in Non-Factory Aircraft", but no life limit is given.

 

[TimRF79]

My question for the AL tanks is not the DOT lifetime, but given they need a hydro every 5yr, in reality after how many years do the tend to fail the hydro tests?

 

[GaryM]

My question for the AL tanks is not the DOT lifetime, but given they need a hydro every 5yr, in reality after how many years do the tend to fail the hydro tests?

Hopefully someone can chime in with actual statistics; I can only say that when I was diving more, I had 12 aluminum and 5 steel tanks of various sizes. Never had one fail a hydro test.

 

[TimRF79]

Hopefully someone can chime in with actual statistics; I can only say that when I was diving more, I had 12 aluminum and 5 steel tanks of various sizes. Never had one fail a hydro test.

I am not (yet) a SCUBA diver, but I think these AL bottles are thicker and bigger than those used in aviation?
Further I suspect that beeing in a plane all the time and having the contraction and expansion due to changing pressure, plus getting a little banged up, may not help lifetime of AL bottles

 

[Checkout_my_Six]

You'd have to talk with a DOT hydro tester (dive shop) to get that kind of info. Based on my discussions with them with regards to my 115 cuft steel tank he told me I should go with a smaller aluminum tank and up the pressure, but, that's a no go for an installed system. I have a manifold that won't go above 1,800 psi....and is not certified for higher pressures. But, it was a nice idea....lol. For $30 hydro test....it's probably the cheapest maintenance item I have.

My question for the AL tanks is not the DOT lifetime, but given they need a hydro every 5yr, in reality after how many years do the tend to fail the hydro tests?

 

[WDD]

Another option - I just bought an empty 02 bottle, and took it to a welding shop where they exchanged it for a full cylinder - similar to your BBQ propane bottle exchange. It's a steel bottle. But the difference is weight between AL and steel for my 20 CF bottle is only a few pounds it turns out - not enough for me to want to buy and keep my own AL bottle.

As I'll do 2-3 trips a year where two of us in the plane will use 02, I'm not getting it refilled but once a year or so.

 

[GaryM]

I am not (yet) a SCUBA diver, but I think these AL bottles are thicker and bigger than those used in aviation?
Further I suspect that beeing in a plane all the time and having the contraction and expansion due to changing pressure, plus getting a little banged up, may not help lifetime of AL bottles

I don't know if the construction differs between aviation and SCUBA bottles. It's possible, since aviation applications are more weight-sensitive, but the DOT still has to certify the bottle for the rated fill pressure and I don't know how much leeway they might grant for different applications.

I'd think SCUBA bottles have the harder life; refills after every single use, banging around on dive boats or over rocks to get to choice shore dives.

Contraction/expansion cycles due to altitude-induced pressure changes in an aircraft would only be a few PSI; pretty negligible compared to a few thousand PSI inside.

The big killer of SCUBA tanks is water on the inside; if a diver screws up and drains a tank at depth, it's possible for water (and salt water will be the worst) to enter, where it may remain undetected in the tank until the next inspection. The resulting pitting can easily cause a tank to fail visual or hydro.

 

[ElPaso Pilot]

You might find a wait list for an O2 system / SkyOx is back ordered to June. There is apparently a bottle shortage. I had to order the cannulas and regulator by themselves and source a welding O2 bottle off of Amazon.

“Medical” O2 bottles are harder to find.

After a few calls, found a local gas shop / hydro tester that had several aluminum O2 bottles in the back. Shop was happy to sell them to me on the contingency that they passed hydro. Changed out the valve/fittings as well to match what I needed free of charge. The rest of the components were much easier to source.

 

[WDD]

After a few calls, found a local gas shop / hydro tester that had several aluminum O2 bottles in the back. Shop was happy to sell them to me on the contingency that they passed hydro. Changed out the valve/fittings as well to match what I needed free of charge. The rest of the components were much easier to source.

Good job!