Questions about Air tanks, ie scuba and carbon fiberAugust 12 2009 at 12:21 AM
Terry (Login TerrySS)
I'm new to the high pressure tank scene. Can someone answer a few questions for me?
1. What is the useful life of an air tank, in years?
2. How long is a hydro good for?
3. Can a tank be refilled indefinitely as long as the hydro is good? 10 years, 20 years?
4. What kind of fitting do I need to fill a Talon SS with a carbon fiber tank, or a scuba tank?
Henry A. Kalakauskis
|August 12 2009, 2:12 AM |
Carbon fiber(Carbon Fiber wrapped aluminum)-5 years hydro(SCBA)
Fiber wrapped aluminum(fiberglass)-3 years hydro(SCBA)
Carbon Fiber:15 years(SCBA)D.O.T hasn't extended yet to inconclusive testing(they haven't been around long enough).
Aluminum/Steel: Unlimited(as long as it passes hydro).
Fiber wrapped:15 years same as CF
Carbon Fiber:Pro/lighter,longer hydro;Con/lifespan/pricey
Fiber wrapped:Pro/lighter than solid aluminum/steel,longer hydro;Con/lifespan same as CF, a little more expensive than SCUBA bottle
Capacities/most commonly used for PCP's:
Carbon Fiber: 88scf/4500psi,66scf/4500psi,44scf/4500psi, and smaller ie:13scf are pony bottles for a minor recharge in the field.
Aluminum/steel:Standard Divers bottle is I believe a 80scf,3200psiMax(most dive shops fill to 3000psi).Luxfer does sell one that accomadates 4500psi,but I think it would be more cost prohibitive than getting a 88 CF tank.You'd have to do a search on the Net to check availability and price for the Luxfer tank.
I used to dive alot when I lived in San Diego and was in the U.S. Navy E.O.D,but I live in Tn. now and haven't looked at a dive bottle in a while.So I might be a little off on exact pressures for dive bottle,but still very close to 3k psi. But I am an active Firefighter and look at my SCBA's and bottles quite regularly. I use the 66scf myself for PCP-Besides free air.
Summarize:Scuba bottle is heavier,will last until it won't pass a hydro, has less capacity/pressure.
SCBA(no U!-Firemans bottle). There are fiber-wrapped(fiber glass older models than CF models). As mentioned, but cheaper, if hydro/lifetime is current.Same capacity as equally stated Carbon Fiber tanks.
Lastly,CF tanks. Expensive,Lighter,High Capacity/pressures,15 year lifespan(longer if you have your own compressor,good luck getting it hydro'd after 15year lifespan-use it and charge yourself at your own peril past that!)
If I didn't answer all your questions, Joe Brancato has a small business on this Yellow selling CF and wrapped tanks(used), he may be able to answer something I failed to cover.
I have a scuba bottle still I use a carbon fiber one because it's lighter and takes more pressure therefore providing more fills on my guns before I have to refill it.
|August 12 2009, 7:25 AM |
Thank you very much Hank. You are very informative, I really appreciate your time to answer my post.
Correction: SCUBA Alum Hydro Requirement is FIVE years, not 3...
|August 12 2009, 8:54 AM |
Just had my new tank hydroed, it's 5-years between hydros. SCUBA tanks can last your lifetime, as long as they pass hydro. A SCUBA tank in regular use gets far more abuse/refill cycles than an airgunner tank.
Used SCUBA aluminum tanks are infinitely cheaper than SCBA CF. Only watchword is to buy a SCUBA tank made after 1991 from 6061-T6 aluminum. Those made before (offered cheaply on e-bay or Craigs list) often are made of a different alloy before 1990, and are USDOT comdemned.
|August 12 2009, 10:14 AM |
I don't recall any recalls or other actions. IIRC Luxfer never used 'the bad alloy'. And very very few have actually failed. Yes, it's dangerous if they do, but since there have been so few AFAIK there is no ban on them, just some internet warnings?
In airgun service you'd expect less problems since the pressure cycles are 'less deep' (guys fill their tanks when divers still would consider them 'mostly full'.
While it's nice to avoid them I guess (better still get a CF or glass fiber tank....), I know of no reason to stop using one you have.
Doug, I learned of the condemnation on this site...
|August 12 2009, 10:59 AM |
Scuba "DOT-E 7235" and "DOT-3AL" tanks made from 6351-T6 aluminum, generally before 1990, are being refused refills at some/most if not all dive shops, due to explosion hazard. At least all the dive shops here in Dallas. No brand is immune... There are several models of Luxfer tanks among them. Here is the article, and the list of "condemned" tanks...
If one is in the market to buy a Scuba tank, you want to buy a DOT-3AL tank made after 1991 if you want no questions asked (or a refusal) at refill time. It's not what we short-fill airgunners feel on the subject, but rather what the dive industry adopts and goes by.
Of course, when I was in Cancun two months ago, the dive shop at our 5-Star resort had the oldest, nastiest tanks imaginable for their day scuba outings. Some had hydro stamps 20 years old, or older, if they had hydro stamps at all. But life outside the US is cheap...
One of the dive shops here (anxious to sell me a new tank) said I could buy one of the hundreds of thousands of these older tanks made, available for cheap + exorbitant shipping on Craig's list, e-bay, etc., if I wanted a really big door stop, as they are worthless for scuba and will draw an automatic refusal for refills.
I have no qualms about buying a used tank, as I purchased a gently used, 1994 Luxfer 80cf in May. Watchword is to shop carefully and ask questions.
|This message has been edited by MB-BOB on Aug 12, 2009 11:04 AM|
Henry A. Kalakauskis
Roger that- on 5 year scuba hydro
|August 12 2009, 6:44 PM |
Like I said, I haven't touched my dive gear since leaving California in 1996, dove just about 4 times a week, more if Bug season. I know the aluminum SCBA tanks we used at work are 3 years for sure(phasing all of them out for CF tanks).Thats where I was apparrently wrong.
O-YAh, anyone want a now condemned tank-thanks Bob, I'll go check my gear this weekend and cry over a useless tank now. What a bummer.
|This message has been edited by Hakalaka on Aug 12, 2009 6:47 PM|