SCBA Tank Life

[AlanMcD]

Any absolutely know for a fact IF the engineers design the slow leak scenario into the tank ? I mean that the slow leak is the design as a safe guard ?

I don't think it was intentionally designed in this way, but from an airgunner's perspective our most likely failure scenario would be from internal corrosion, should water condense and accumulate in the tank. The aluminum liner would corrode away, and then the air pressure would probably work through the resin that binds the fibers. I don't know that I would call that a "slow leak" scenario, but it certainly would not be an explosive decompression . . . most likely a loud pop and whoosh as the resin lets go.

Of course the burst disk is the intentionally designed in safety feature, from an over-pressure situation . . .

The duty cycle these tanks see in most airgunning scenarios is laughable - minimal handling, typically filled slowly, rarely drained down by even half before being refilled, and fewer of those less loaded cycles than fire stations do. As long as we keep water vapor out they should be fine for a very long life.

But each person has to make their own decision on their own tank . . . .

 

[DesertSilver]

Like you've said, we don't push these tanks anywhere near what the fireman do. It's like having a acrobatic plane that is flown like a Cessna 150.

 

[Geezerhood]

The DOT is allowing recertifying SCBAs for another 15 years of service once they turn 15. I think that pretty much covers the 30 year life. Recertification doesn't change anything on the tank other than actually weakening it somewhat by pumping it up to 7500 PSI.

 

[18.13]

The DOT is allowing recertifying SCBAs for another 15 years of service once they turn 15. I think that pretty much covers the 30 year life. Recertification doesn't change anything on the tank other than actually weakening it somewhat by pumping it up to 7500 PSI.

The recertification is not a hydro test it's more like a ultra sound, also vary expensive $300 and has to be done every 5 years so $900 I'm buying a new tank

 

[JimD]

Remember, the most frequent cause of failure for the Navy is thread damage from hydro testing. The only form of failure they've had in thousands of tanks is a slow leak. It's in the report. We don't have to guess there is a lot of experience to back up a slow leak is the expected mode of failure.

I am also of the opinion that keeping water out of my one tank is highly likely to let it outlast me. If I ever notice significant damage to the carbon fiber, however, I will dispose of it and get another expired firemans tank. If it ever leaks, I will dispose of it and get another.

If others want to spend more on tanks that is fine by me. If it makes you feel safer and have the money, great. I am more worried about my compressor failing than my tank. But I doubt either will be catastrophic.

I don't like people showing a tank that was intentionally damaged and then grossly overpressurized and pretending that is a reason to only use hydro tested tanks. Not honest at all. Unless a tank showed no visible sign of damage and failed at 300 bar or less, I don't care what the picture looks like. I don't think such pictures exist. It could happen, however, if enough moisture got into the tank. But I am pretty confident it still wouldn't be ripped apart, it just would have a leak. Might not even show damage. The carbon fiber will not hold air. If the aluminum liner gets a hole it will leak. Probably slowly and a picture would be quite boring.

 

[Trucker3573]

The recertification is not a hydro test it's more like a ultra sound, also vary expensive $300 and has to be done every 5 years so $900 I'm buying a new tank

Yes this is absolutely true. The 15 yr recert just doesn’t make sense from a financial standpoint.

 

[L.Leon]

Well it's not like micro cracks are going to stick out and say here i am ..lol

My thing is is it worth the risk that one day at 3000+ psi it cuts loose and takes out you standing there or anything in proximity? .. not me id prefer to just go with a tank that can be hydroed / us dot and filled at any shop if needed .

Then some feel it's well worth the risk .. idk. Just hope i aint standing there when it bursts.. ouch.

SCBAs “by design” do not fail catastrophically, firefighters wear them on their backs! I don’t believe any HPA compressors you can buy for personal use are capable of “blowing up” an SCBA. Some other part of the fill system would fail first… fittings, valves, etc.

 

[rcs9250]

I stop using them when they blow up.

 

[Geekmedic]

Most SCBA bottles that fail catastrophically do so when they are filled. I am aware of several failures over the last 30 years since I started firefighting. It pretty much always happens as a result of a refill. That is why we put SCBA bottles in a 3/8" steel sleeve and lock them behind a steel door when we re-fill. The one thing you to need to take into account about SCBA bottles failing is that firefighters often lay on their side and slide along the floor when training, performing a rescue, etc. The bottles that fail usually have a spot that has received enough friction that there is a thin spot in the epoxy impregnated carbon fiber. The most spectacular failure I am aware of occur several hours after a re-fill while the bottle was stored in a fire truck. It opened the side and roof of the cab of the truck like it was a tuna can.

 

[ske1eter]

The report done for the Navy confirmed the only mode of failure they have seen has been slow leaks. Mostly from thread damage from doing hydro tests. That mode of failure being at least the most likely mode make me more confident using my "expired" Scott tank. The navy report concludes that the 15 year life doesn't really have a scientific basis.

I think that this is the study referenced.

https://www.phmsa.dot.gov/sites/phmsa.dot.gov/files/docs/technical-resources/55976/navy-self-contained-breathing-apparatus-scba-composite-cylinder-life-extension-research-project.pdf

I'd trust the results from an extensive and expensive study rather than anecdotes.

 

[Centercut]

Yes this is absolutely true. The 15 yr recert just doesn’t make sense from a financial standpoint.

It makes total sense financially - for the tank manufacturers. Think about it. Thousands of Fire Companies across the nation pay big bucks ($1000+? Each) to replace their tanks. So at the 10 to 12 year point they look into getting a new contract to have them replaced. Now what were to happen if the DOT extended service life to 30 years? Those same manufacturers would make less than half of what they do now. Or they would double the price for “new 30 year tanks” which are identical to the 15 year tanks. The lobbyists in DC would fight a life extension big time…

 

[Geekmedic]

I think that this is the study referenced.

https://www.phmsa.dot.gov/sites/phmsa.dot.gov/files/docs/technical-resources/55976/navy-self-contained-breathing-apparatus-scba-composite-cylinder-life-extension-research-project.pdf

I'd trust the results from an extensive and expensive study rather than anecdotes.

The Navy study assumed tanks with no damage in good working order, and only addressed tanks that were past 15 years and had no wear. It is not anecdotal to say that there have been multiple SCBA bottle failures during re-fill over the past couple of decades. That is a fact. However, those failures have been in bottles with wear and tear as a result of use that made them more likely to fail during a re-fill because the structure of the tank had been compromised. Additionally, that is a handfull of failures across tens of millions of re-fills in hundreds of thousands of bottles. I believe the Navy study is absolutely accurate, and tanks can easily go beyond 15 years and still be serviceable. I would not be as confident if I got a 15 year old bottle from a fire department that was active in training and firefighting.

 

[Trucker3573]

It makes total sense financially - for the tank manufacturers. Think about it. Thousands of Fire Companies across the nation pay big bucks ($1000+? Each) to replace their tanks. So at the 10 to 12 year point they look into getting a new contract to have them replaced. Now what were to happen if the DOT extended service life to 30 years? Those same manufacturers would make less than half of what they do now. Or they would double the price for “new 30 year tanks” which are identical to the 15 year tanks. The lobbyists in DC would fight a life extension big time…

I was referring to us hobbyists. It doesn’t make sense you might as well buy a new tank. One must remember in addition to that several hundred dollar test every five years you have shipping costs in both directions. Ouch !!

 

[airgunmike56]

Oh my , Reminds me of the weed videos they used to show in schools 50 years ago..
Now I am not for legal weed , But the old moves were called reefer madness ,, Anyone remember those
Mike

 

[JimD]

I think it is pretty easy to inspect a tank for damage to the carbon fiber. You are looking for damage that has some depth - not scuffing. Mine looks nearly new. The guy I bought it from would have readily replaced it if there was an issue. I thought at first I had one but it was the fill set, not the tank. He told me that but said he would send a different one anyway. I told him I'd try the fill set first and it was the issue. I would not doubt there are ebay suppliers that are not as good but I know there is at least one that is fine. I don't think he sells tanks with any visible or known damage. Carbon fiber is not easily damaged. It just needs to not be beat up.

 

[delooper]

Just don't go diving with your SCBA tank at the bottom of the Mariana Trench.

 

[rcs9250]

There are a couple bags available for protecting CF SCBA’s. And there are some DIY methods as well. Air Tanks For Sale sells a mesh sleeve. It protects the tank when you’re sliding it around but does not protect it from impact from a sharp corner of something like a metal cabinet corner. That could condemn a tank.
I have been keeping my eye open for some plastic drain or water line pipe, usually usually green colored that my 74CF tank will fit into and add a bottom and top and a handle.
I quick and dirty tank protector is a piece of corrugated cardboard that is wrapped around the tank about three lauers thick and some strapping tape to keep it from unravelling. In the old days, campers ised to shellac the cardboard boxes their Coleman lantern and stoves to make them last and sorta waterproof them. The cardboard tank protector could be coated with brush on or spray on polyurethane to protect it too.

 

[JimD]

I made a "tray" for my bottle to hold it and also little things I use with it. I used cyprus which is pretty soft because I had some around. It has half circle cut outs so the bottle stays put. The tray adds a couple pounds weight but makes the bottle easily portable and protects it from damage.

 

[rcs9250]

I made a "tray" for my bottle to hold it and also little things I use with it. I used cyprus which is pretty soft because I had some around. It has half circle cut outs so the bottle stays put. The tray adds a couple pounds weight but makes the bottle easily portable and protects it from damage.

Can you post a photo ? Is it able to stand vertically ?

 

[bchannell]

You guys all know that with thousands of cylinders in service there have and will be failures. I've read of only one that had no real solution as to why. IIRC it was a firefighter in the rear crew cab of a firetruck who was killed when the tank exploded. I'm going from memory but the tank had no damage and was relatively new and just went. I used to do fire work at a chemical plant and we got info from incidents all over the world and I remember hearing of one blowing up just as it was finished filling but there was a good reason I just don't remember.
I've filled many hundreds, if not thousands of CF 4500psi cyls in my day. I even filled over 150 in one day during a huge fire. Some cyls looked rough but thank God no problems.
There is a huge safety factor in theses IIRC the tested burst was something over 11000psi (17000 if memory Serves) and we were always told by those in the know that the epoxy getting brittle was the limiting factor, but that didn't occur for way more than 15 years.
I would choose a good clean cyl that has had minimal fill drain cycles, like those that hang in Chem plant control rooms and I would use it for many years past it's 15 year date. It is the cycling of the cyl that kills them that why the REE number for Hydro test.