high pressure carbon fibre tanks

Discussion in 'Tanks, Valves and Bands' started by Jimi, Feb 27, 2005.

  1. Jimi

    Jimi Angel Fish

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    I play competitive paintball, and only now, as i am preparing for the Ambush Reflex Tournament, do i realize what paintball hpa tanks can do for scuba. How they work is that they have a thin (o.5cm) wall of aluminum on the inside, and the same thickness in tightly-wrapped carbon fibre. They can hold up to 5000 psi (the average scuba tank holds about 3000) and the are extremly light due to the materials they're made of. Because of this, you could have a light, small and easily portable tank that can hold a lot of air. The only drawback is the price; a 5000 psi 88ci tank is about 300 usd, but they include a high quality regulator, and im sure the price wouldnt increase that much as the size increases, becuase the materials are relativly cheap. any thoughts?
     
  2. CBulla

    CBulla ~..facebook conch..~ ScubaBoard Supporter

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    This has been talked about before - its a weight trade off. Your tank may be lighter but you'll need to weight down more somewhere else to make up for it. Also for about $300 you can get a 100cf steel and drop almost all the weight off your belt.
     
  3. Damselfish

    Damselfish Orca

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  4. crpntr133

    crpntr133 lost, even with a compass

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    You might have troubles getting someone to fill it also.
     
  5. SeanQ

    SeanQ Single Diver

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    I don't have any numbers but I imagine that the bouyancy swing would be quite large. The only benifits to SCUBA that I can think of is that they are easy to haul around on land or boats. That isn't really a benifit when you consider how much extra weight you'll have to carry to offset the tank.

    While these tanks are great for land use (firefighting, paintball, etc.) they are detrimental for usage in SCUBA. No thanks, I'll stick with steel and aluminum.
     
  6. jonnythan

    jonnythan Knight Scublar ScubaBoard Supporter

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    The buoyancy swing only depends on how many cf of gas you breathe, it has nothing to do with the tank itself.

    To repeat everyone else, imagine how much lead you'll have to strap to that tank to get it to sink!
     
  7. Amphibious

    Amphibious Scuba Instructor

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    they are far to boyant to be practical. period.
     
  8. jonnythan

    jonnythan Knight Scublar ScubaBoard Supporter

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    What about a manufacturer making a fiber-wrapped tank that has about the same amount of steel as a traditional tank, so you have the same buoyancy characteristics, but have a service pressure of more like 4500 psi?

    Imagine having a tank the size of an LP 104 but a fill of over 177 cf at service pressure. Or fitting over 100 cf into a tank the size of the super tiny HP 80?
     
  9. teknitroxdiver

    teknitroxdiver Great White

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    The tanks like firemen use have terrible buoyancy characteristics, but the Luxfer carbon fiber tanks are quite manageable. Although you would still probably have trouble getting a good fill on it.
     
  10. JS1scuba

    JS1scuba Scuba Instructor

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    IN 2003 Luxfer introduced the Luxfer Limited 4350 PSI HoopWrapped Aluminum Cylinder. These things were / are great. They come in 2 sizes. 106 cuft and 85 cuft. The 106 is the same physical size as an aluminum 80 and the 85 is the same physical size as the alum 63.

    I had/have the first batch that came out of the factory and was doing the water tests on them. They were/are outstanding tanks. The bouyancy of them is great and they are nicely balanced. Only one thing ...... if you want the rated volume you gotta have the 4350 psi pressure. If you can only fill them to 3000 psi then you have effectively an 80 and a 63.

    The price on these retail is in the $325 range which put them in line with HP steel. The only problem from a marketing standpoint is that there are few dive centers set up to fill them. As a result they were a dud. At best I belive they sold a few hundred. But they are still available on a custom order basis.

    These are a standard thick aluminum with what i like to call the "kevlar girdle" to help with the greater pressure.

    Carbon Fiber wrap cylinders were used early in tech diving as experiements. These are very light and hold a lot of gas at 4500 psi but float like a cork --which makes them unattractive for diving.

    The big market for carbon fiber wrap cylinders is the home-health care market for granny to tote her oxygen bottle around and not feel like she is lugging a bowling ball.

    Paintballers also love them for weight and agility.

    Hope that helps you.

    Regards,
     
  11. mike_s

    mike_s Blue Whale

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    But the yoke on your 1st stage is only rated for something like 3000psi-3300psi.

    A din is rated to I think 3500psi?

    Take the weight issue out of it as the isn't a 5000psi regulator made for life support.
     
  12. jonnythan

    jonnythan Knight Scublar ScubaBoard Supporter

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    I thought I had a great idea for once. Surprise, someone's already done it :p
     
  13. JS1scuba

    JS1scuba Scuba Instructor

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    Sorry -- this stuff is kinda old hat ..... divers have been messing with SCBA bottles for years .... they just dont work for what you want to do with diving.

    Regards,
     
  14. roakey

    roakey Old, not bold diver ScubaBoard Supporter

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    300 BAR DIN = 300 BAR * 14.5 PSI/BAR = 4350 PSI.

    Roak
     
  15. JS1scuba

    JS1scuba Scuba Instructor

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    DIN means Deutsch International Norm ........ it's a thread size

    300 Bar = 4350 psi
    232 Bar = 3364 psi
    200 Bar = 2900 psi

    A 300 Bar rated cylinder will take 4350 psi.

    A 300 Bar DIN outlet Valve only means that the valve has a 9 thread count and can take a 9 thread DIN male connector. IT is the base or "boss" of the valve that determines the pressure it can acccept from the cylinder.

    A "high pressure" cylinder ie 3500psi-4350 psi will have a small neck opening where as a "lower pressure" cylinder ie 2015-3442 psi will have a larger 3/4 inch neck opening.

    Fill 'er UP

    Regards,
     
  16. derwoodwithasherwood

    derwoodwithasherwood Barracuda

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    Now that's an interesting point. While it's true that more weight on the belt would be needed to offset the cylinder's bouyancy, that weight would only need to be carried to the dive site once. On a multi-dive day that means less total weight needs to be hauled to and from the beach or boat. Less physical effort is a good thing from a DCS perspective.
     
  17. jonnythan

    jonnythan Knight Scublar ScubaBoard Supporter

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    You leave your weights on the beach while you go home and sleep?
     
  18. Bob3

    Bob3 Dive Shop

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    The "finding a good fill" problem, along with the cost make the composite bottles a pass, at least in the US. They've been in use in Europe for quite a few years & they've been able to work out a lot of the "undesireables", like a short lifespan.
    I have a set of little doubles from the early '70s that are rated to 4400 psi, I don't think they've ever been pumped up anywhere near there.
     
  19. SeanQ

    SeanQ Single Diver

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    Yep. Around here we call them "rocks". They become a problem when beachcombing tourists want to take the "pretty rock" home with them.
     
  20. Vie

    Vie Tech Diver

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    I can't remember where I read this, but didn't the early carbon fiber tanks have some kind of leakage problem - they were too porous for helium or something?
     

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