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Thread: HP 83 Cu.Ft 4500 PSI/ 300 BAR Steel Tanks

  1. #1
    TadPole
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    HP 83 Cu.Ft 4500 PSI/ 300 BAR Steel Tanks

    I have the chance to purchase two steel 4500 PSI tanks for 75 each. New Hyrdo and VIP. They are DIN with a screw in for Yoke.

    My questions:
    1. My first stage is stamped with 3500 PSI. So until I convert them to doubles, I would need to buy a new first stage? With my regs be OK?
    2. I checked Jarrod's DIR book, and nothing is mentioned on tank size. Are these little guys considered DIR or does it not matter? I want to take the GUE class in doubles.
    3. Are these good tanks to convert to doubles in the first place?
    4. Any other advise on steel tanks like this from the DIR perspective?

    I posted this in DIR and not in tanks because I am interested in not just the tanks but what you guys with DIR backgrounds think. Feel free to move the post if necessary.

    Thanks,
    Jerrod

  2. #2
    Never heard of a 4500 PSI steel scuba cylinder. Most cylinders are 3442 PSI because anything under 3500 PSI can use yoke. You can find older cylinders which are 3500 PSI but only come in DIN because yoke is only rated for 3442 PSI. Heiser manufactured cylinders which were 4400 PSI but these tended to hold a LOT more than 83 cu.ft. of air. If the cylinder has a DIN valve which can be converted to yoke then that valve is rated for cylinders under 3500 PSI (typically 3442 PSI). Any cylinder rated for 3500 PSI or higher should have a DIN only valve (300 bar).

    So I would expect to see a cylinder rated for under 3500 PSI with a 200 bar valve (DIN/yoke convertible) or a cylinder rated for 3500 PSI or higher with a 300 bar (DIN only) valve.

    What you are describing is a 4500 PSI cylinder with a DIN/yoke convertible valve (200 bar). This is not a combination you should use. It would allow you to use a yoke first stage with a pressure beyond what any yoke attached is rated for. If this is the case than it is not DIR. If you brought this cylinders to any shop I work at (not DIR) and wanted it filled beyond 3442 PSI with a 200 bar valve, we would not fill it. So not only is this not DIR, it just isn't safe by anyone's standards.
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  3. #3
    Barracuda
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    XSScuba making a LALW106 that are high pressure tanks 4350 PSI for a number of years but are 105.2 Cu Ft. I would stay away from these since they will hard to find shop that fill them and buoyancy of these style of cylinders is not ideal for doubles since the go from +2.1 full to -4.8 empty.

    This is a special cylinder manufactured by Luxfer. It is a composite cylinder manufactured of both aluminum and fiberglass. It starts out as a standard
    scuba 80 cuft cylinder. Hoop-wrapped fiberglass and resin is added to strengthen
    the side walls. This allows for an increased service pressure to 4350 psi and a capacity of 106 cubic feet. This cylinder falls under DOT Special Permit 12479. Requirements of SP12479 is a hydro re-test each three years and a fifteen year service life. The inlet to this cylinder is unlike most other scuba cylinders, utilizing 7/8" x 14 UNF threads (a smaller hole). The choice of valves is restricted to a 300 bar DIN valve with the correct 7/8" x 14 UNF threads.
    - Dennis ><()))">

  4. #4
    I didn't consider carbon fiber cylinders. I assumed they were steel and around 83 cu.ft. Having the yoke insert implies the valves are 200 bar. Claiming they fill to 4500 PSI implies they require 300 bar valves. Something has to be wrong or these are 'frankenstein' cylinders most shops will not fill.

    I thought they were something like: http://www.amazon.com/Sherwood-Divin.../dp/B0013AM478. I believe these are Worthington HP80 cylinders with Genesis 200 bar convertible valves. The description claims you can fill them to 3500 PSI and the true capacity is 83 cu.ft. but the reality is you should not fill them beyond 3442 PSI with a 200 bar valve. Therefore they are really 80 cu.ft. and not much different from the XSScuba tanks.

    The more I look at Jerrod's description the more I think they are really just HP80 with 200 bar convertible valves. ScubaToys sells Worthington HP80 with Thermo Pro valve for $350. if these are Sherwood cylinders with a Genesis valve then I would expect them to sell for less (the Thermo Pro valves are better than the Genesis).
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  5. #5
    TadPole
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    Thanks for the comments. I bet the guy has told me wrong about the pressure. They are very small (at least 6 inches smaller than your typical al80). They almost look like scba tanks but bigger.

    See they have a bunch of tanks that people have left behind for years and I want to talk them into selling them to me for a discount? (Any advise on that front appreciated).

    My GUE instructor said the small tanks make you feel front heavy sometimes, so that is something I want to take into account.

    Jerrod

  6. #6
    Steel tanks have pretty good resale value because they seem to last forever. I know tanks that have been in service for decades (30+ years). Aluminum tanks from before 1990 are questionable. A lot of shops won't fill them due to SLC but I've never known any shop to refuse to fill a current steel tank. For this reason, I usually never see good steel tanks for a huge discount. When I do see steel tanks for a really low price it is usually because they have rust and cannot be saved. Bottom line, you will end up paying a fair to high price for a good steel tank.

    I don't think small tanks make you feel front heavy. If I have my weight properly trimmed I don't notice small tanks having any effect. I can see that short tanks might make you feel head heavy but if you have negatively buoyant fins having short tanks might help. Or if you have a short torso, short tanks will work better for you. I'd never make the blanketted statement that short tanks make you feel head heavy.

    You might want to checkout the specs for Worthington cylinders at http://www.xsscuba.com/tank_steel_specs.html. Also How to Select a SCUBA Tank - Dive Gear Express is a good read as well.
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  7. #7
    TadPole
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    Well as luck would have it, I called my instructor and he has found two sets of doubles for sale. They are Faber 95 cu.ft LP 2400 PSI, 10 years old, out of hydro in about 6 months. He wants 400.00 per double set. It will cost me 150 per set to bring them current (VIP, Hydro, O2 cleaning). I think this sounds like an excellent deal. Worst case I can break them apart and use them as singles until I have the money to buy a new wing.

    There are some good double wings I have seen on scuba toys.
    This one looks good: HOG 58Lb Air Cell discounts on sale HOG

    I need a double bladder wing if I am diving wet, right? Are there any other alternatives? Those wings are quite expensive.

  8. #8
    Barracuda
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    Jerrod, you GUE instructor is absolutely correct the short tanks can make you head heavy and on a taller person could have a really hard to get the tanks to trim out at all. Most people diving doubles will have a head heavy problem and thatís why you see a lot Tech Divers using the heavy rubber fins to offset some that forward head heavy trim. If thatís not enough you will see tail weights on their back plates but the problem is diving wet you need to avoid adding to much trim weight to you kit since you will already be over weighted at depth. You want to avoid ankle weights at all cost, that is patch to problem that need to be solved. My first dive in my steel 72ís doubles I was so head heavy I put 2lbs weight in each boot and could of use another couple pounds. I have switched to Hollis F1 fins and 3lbs tail weight for trim. I now dive Sidemount and the opposite is true, in Sidemount you are feet heavy and need light fins to offset it.
    You need to talk to your instructor about each and every equipment purchase you make be sure he agrees or you will be buying twice. I will say if I were you are diving wet and that over weighted with 95ís I would consider a dual bladder wing, sure won't want be 100 feet deep and find that I to heavy to swim the kit up or even worse on wall dive with bottom at 1000 feet with failed wing. But again run by your instructor he may not agree.
    You are also going to have a talk with instructor about what he wants in way of balanced kit, I know one GUE instructor that won't take one students diving wet in steel tanks he make then use doubled AL80's.
    Last edited by CWSWine; 05-15-2013 at 10:39.
    - Dennis ><()))">

  9. #9
    TadPole
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    CWSWine, you got me scared with the 1000 foot wall and a failed wing!

    So in general, doubled AL80s wet is considered OK? I could always buy the steal for 400, and the local dive shop sells the AL80s for 100 each, and convert the steel to singles and the AL80s to the doubles. Would all those manifolds and yokes work fine to swap out?

  10. #10
    AL80s will be 7.25" diameter. I'm not familiar with the Faber 95s but I believe they are 8.00" diameter. So bands for doubling the Faber 95s will not work with the AL80 tanks.

    I dive steels as singles. If I am diving 3mm full wetsuit I find I need no lead. I think I might actually be a few pounds heavy. If I'm using 7mm full wetsuit then diving a single steel with a little weight is fine. So if I had a wing failure I could drop weight and make it to the surface. Realistically, I always carry a large DSMB on a spool; if I had a wing failure I'd use my DSMB to pull myself to the surface.
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