Filling an outdated carbon fiber/aluminum SCBA bottle

I use an out of service Carbon tank in pristine condition inside/out likes yours. I personally only fill it to 4100-4200 psi instead of 4500, which is more to keep stress off the compressor filling it than the tank but its a two birds one stone kind of thing.

-Matt

Personally, yes I do use out of date tanks - even one that does not have a "pristine" exterior. It was an old firehouse tank bought used, and passed hydro before I ever used it. It is only filled to about 35600 or so and is used to fill 3000 psi and under guns, and for benchrest sessions at home. I would not take that particular tank to a range as it so obviously old, but have no issue filling and using it myself. But I do make sure my fills are bone dry with approptiate desiccant filtering.

Is this a tank about which you know at least some of the history? If it was mine (or was somebody I trusted) the whole life then I would certainly use it. If I did not know, or it was just given to me, I'd be less certain about it, and likely would not fill it much above 3500 or so . . .

I have four out of date firemen 147cc scba, got these from firestation-government auction sale somewhere back in 2018 for $150 total. The last testing was done between 05 and 07 on these according to stickers. At least two of these tanks full to 280 ish any time of a day/month and storing all four in my basement locker away from traffic.

You can do it. If something bad happens and you hurt someone else... the lawyers are going to have a field day with you.
We just had a 4th grader killed on the way to school yesterday. The Sheriff's exact words were..."A girl died because someone couldn't follow the rules".
That person is going to have a great time in front of a judge.

Self filling ... YES as many of us do on otherwise pristine bottles. Old scabbed up ex firefighter bottles .. not so much

As there are no accounts of fiber wrapped SCBA bottles exploding, when the liner gives out it is a slow leak that never stops.

And the irony is that a carbon fiber wrapped bottle that is never hydro tested is more likely to outlast one that is tested regularly.

A leak down during use could be a fatal failure if it is being used as a breathing tank. So regular hydro testing is warranted in order to catch a potential impending issue. A leak developing in a tank is not catastrophic for one that is only used to fill airguns. If the failure mode of carbon fiber wrapped tanks is never explosively catastrophic, then for airgunners there is logic to never hydro testing and then we use the tank for as long as it passes visual and still holds air. That maximizes the utility of the tank.

I’m not advocating either way. Just saying.

Well , here you go this pictured tank is 23 years old (dob 02/01) and the other tank in my cascade system is 13 years old. So there is a total of 36 years of use of my two tanks. I fill to 5000 psi and then when they cool down they are at 4500 - 4600 psi. Thankfully , I am still around to post , so , so far so good.

There will be no galvanic corrosion between the aluminum liner and the carbon fiber because there's a layer of fiber glass in between. As Motorhead stated,the only thing that will happen if the liner fails is it leak.

No leaks , no worries. Everything is good to go. These tanks are purposely overbuilt to install a safety factor in them.

A 4500 psi tank is hydro tested to 7500 psi. That’s a pretty good safety factor. I fill my expired ones to around 4000 psi.
Your milage may vary.

I've read about them failing at around 15,000 psi. They're probably designed with a 3.5 safety factor which means 3.5 times 4500psi.

Barnamwam said:

At the risk of subjecting myself to some scolding for even considering such a thing, I have a 18 year old AIr Hog 68 cu ft bottle that I am reticent to throw out just because it is outdated. The carbon fiber on the outside is pristine, no dents or cuts. Endoscopic examination of the bottle's aluminum interior shows shiny aluminum with no corrosion or pits. Obviously, I have no idea if there is galvanic corrosion at the interface between the inner aluminum bottle and the carbon fiber wrap. The SCUBA or "safety store" will not even look at it because it is out of date. They would be happy to sell me a new replacement.

Would you use it and enjoy it or toss it and replace it?

Mike

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Check out Aaron Cantrell's youtube vid on out dated tanks. Same tanks that are 15yr certified in US are certified for 30yrs in Europe. May have Cantrels' name wrong, but it's close enough to get you there.

DesertSilver said:

I've read about them failing at around 15,000 psi. They're probably designed with a 3.5 safety factor which means 3.5 times 4500psi.

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5/3 is the standard, FWIW.

oregondude said:

Check out Aaron Cantrell's youtube vid on out dated tanks. Same tanks that are 15yr certified in US are certified for 30yrs in Europe. May have Cantrels' name wrong, but it's close enough to get you there.

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SCBA tanks can be extended to 30 years in the US, too. But instead of using damaging hydro testing, they switch to non-destructive MAE testing.

Trouble is, it's about the same price to take a tank to 30 years as it is to buy a brand new tank.

F6Hawk said:

SCBA tanks can be extended to 30 years in the US, too. But instead of using damaging hydro testing, they switch to non-destructive MAE testing.

Trouble is, it's about the same price to take a tank to 30 years as it is to buy a brand new tank.

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So a MAE test is over $100? If you hydro for 15yrs, then only 3 MAE tests would get you to 30yrs. That would put the MAE at $200 per test assuming $600 for new tank. My 21yr old Scott was $60 shipped. No additional costs.

oregondude said:

So a MAE test is over $100? If you hydro for 15yrs, then only 3 MAE tests would get you to 30yrs. That would put the MAE at $200 per test assuming $600 for new tank. My 21yr old Scott was $60 shipped. No additional costs.

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I’m in the process of weighing the pros and cons of using old tanks myself. I have two scba fire tanks decommissioned and in “well used condition“ I may continue using one of them while the second holds air but is more beat up-it will probably get drilled or pressed up and shot from an extended range for the show…

They both hold air, and don’t appear to do anything weird when filling, but it still makes me cringe a little. Then again given their safety margins I may be fretting about nothing.

Knowing that in many markets they are allowed a 30 year service life makes me feel a little better though.


For me it was a cost saving measure, sure I want a “great white” tank with all the bells and whistles with the regulator tether so I can hook it up and shoot all day, but this gets me the quick fills til the budget allows “the thing“.

My first fill ended up having a moisture issue though, humid day, and my inline Chinese filter blew a gasket at 2k psi due to faulty machine work on the filter bodyone cap didn’t seat square…I finished up filling using the tiny yong heng inline filter, and regular valve bleeding, but that proved inadequate. The Tuxing double stack filter, with a second Tuxing gold inline desiccant filter is on the way to remedy that situation.

After a great white tank, I’ll start saving for an Alkin compressor, so the costs never end lol. I just won’t tell my wife how deep this is getting! Otherwise she might just shoot me to stop the financial bleeding….

F6Hawk said:

5/3 is the standard, FWIW.

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Question for clarification I’m guessing you mean that 5/3 of the rated pressure is used for hydro testing? I’m still pretty new at all this and trying to get it all straight in my brain lol. There’s a lot to learn.

I think the prior post you were replying to was referencing the engineering safety margin -or the pressure it will fail at is 3.5x the rated pressure? Which I think is the industry standard? I feel like I read that somewhere referring to pcp pressure tubes.

oregondude said:

So a MAE test is over $100? If you hydro for 15yrs, then only 3 MAE tests would get you to 30yrs. That would put the MAE at $200 per test assuming $600 for new tank. My 21yr old Scott was $60 shipped. No additional costs.

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According to a phone convo with the good folk at Hexagon Digital Wave about the DOT extension of 15 years via MAE testing:

$375 (plus shipping both ways the 5th year/20 overall), then $110 (plus shipping both ways) the next two 5-year cycles. (Cheaper just to buy another new tank and have it shipped once.)

So in addition to the cost of a new tank and two hydro tests, one will pay about $595 (plus two-way shipping 2 times) to extend the life of a SCBA tank to 30 years.

Or buy another new tank. Or ignore safety and just keep filling at home and risk an explosion. It's all about choices.