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al vs steel

Discussion in 'Tanks, Valves and Bands' started by Too$hortbaby, Dec 26, 2000.

  1. Too$hortbaby

    Too$hortbaby Angel Fish

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    i was wondering if theres any advantges/or disadvantges for steel or al tanks?

    i dive in cold water 99% of the time,i don't know if this will matter.

    thanxs
     
  2. Rick Murchison

    Rick Murchison Trusty Shellback Staff Member ScubaBoard Supporter

    # of Dives: 2,500 - 4,999
    Location: Gulf of Mexico
    13,348
    552
    113
    The only reason to buy a standard aluminum 80 is cost. If you can afford it, you will love the buoyancy characteristics of steel, and LP tanks are much easier to get filled than HP anywhere you go. My personal favorite open water tank is still the original steel 72, a little smaller and lighter than the 80, but I can dive it with no weight at all in warm water - and as I'm usually diving with others it is a rare thing indeed that my tank pressure is the one that calls the dive. If your air consumption is average, then my recommendation for the absolute best tank is the OMS LP 85. You will *love* it - it's essentially the same size as the aluminum 80, (it's actually a little smaller and lighter, but as steel tanks have round bottoms and you'll probably use a boot, it'll appear the same size) but you can shed eight pounds from what you have to carry with an aluminum. If you really need the air, a steel 95 will let you shed 12 pounds, but now we're getting into a heavier, bigger tank.
    Since you're diving in cold water the ability to shed weight is worth a lot. In a typical 7mm neoprene drysuit with thermal underwear, for example, with aluminum 80 doubles I'd have to carry 24 pounds in addition to my typical cave rig; with twin OMS 85's, I only carry 8 pounds.
    I personally don't like HP tanks because of extra wear and tear on the high pressure components of the regulator, and the combination DIN fitting and high pressure makes a fill unavailable in lots of places. (Yeah, folks routinely put a yoke adapter on there and fill to 3500+ with a yoke, but it ain't smart since yokes aren't rated for it)
    Rick
     
  3. Mario S Caner

    Mario S Caner Member

    # of Dives: I'm a Fish!
    Location: San Diego, CA
    1,803
    4
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    Too$hort, There's only one single benefit to owning an Aluminum cylinder, and that's cost. A steel cylinder, especially HP cylinders are considerably smaller that the Al equivalent. The reason is simple, steel is a much stronger material and therefore they can get away with having thinner walls, especially in the boot and neck area.

    The downside to steel is price. If that's not an issue for you then we can move into HP vs LP. It's true that the vast majority of technical divers use LP cylinders. The reason for that is because LP cylinders like OMS have a 10000 cycle Hydro life. Most usually fill their cylinders beyond the 10+ overfill allowance to cheat some more bottom time out of it. LP is heavier for the same size as HP. LP is gentler on your regulator.

    It's difficult to get a truely good fill on a HP cylinder because dive shop personnel don't like placing the cylinder in water, filling it, waiting for it to cool off, and then top it off. It's time consuming. It's not that the compressor doesn't have the capability, it's a time thing. In fact if a shop tells you they aren't configured to fill HP, walk away and find a new shop. One with upto date equipement. HP is costlier than LP.

    Here's a :nono: I stopped by a shop to have my cylinders filled on the way to a Lobster dive a couple of years ago. I usually fill my own cylinders but I had to stop by the registers to get a new Fishing Lisence, so I let the dive shop manager fill it. The dope filled my 2400 psi rated cylinders to 3700 psi. Hehe, nothing happened but the 133cuft of air didn't hurt.

    So in conclusion, I use LP because it fits my large frame, and the type of diving I choose to take part in. Your needs may be different.

    Mario :D


     
  4. Too$hortbaby

    Too$hortbaby Angel Fish

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    thanxs all

    does any one have a cure for dyr,scratchy gills?

    or should i start a new thread.
     
  5. Mario S Caner

    Mario S Caner Member

    # of Dives: I'm a Fish!
    Location: San Diego, CA
    1,803
    4
    0
    Unless your gills are either Al or St, then you should start a new thread.

    Mario :D
     

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