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HP vs. LP / High Pressure versus Low Pressure steel tanks

Discussion in 'Tanks, Valves and Bands' started by bigcat, Apr 13, 2002.

  1. bigcat

    bigcat Angel Fish

    # of Dives: 200 - 499
    Location: Kent, Ohio
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    Anybody have any thoughts about what would be the better purchase LP or HP steel tanks? LP tanks seem to be more popular because of the overfill capacity. LP tanks are good for a +10% overfill for the first five years. However, after the first hydro, a 98 cu. ft. tank is reduced to 89 cu. ft. Conversly, a HP 100 at 3500 psi is 100 cu. ft. for life. Is it really that difficult to get a good fill with a HP tank? An HP 3500 tank filled to 3000 psi has only 86 cu. ft. of air. Not much more than an AL 80. And what about the preception that HP is hard on regulators? Yur comments please!
     
  2. Uncle Pug

    Uncle Pug Swims with Orca ScubaBoard Supporter

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    LP tanks can be re-tested to the + rating
     
  3. bigcat

    bigcat Angel Fish

    # of Dives: 200 - 499
    Location: Kent, Ohio
    69
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    Pug, how difficult and expensive is it to have LP tanks recertified to +10% rating? LP seems to be the tank of choise lately. However, why not go to HP rather than continuously overfill an LP tank. Also, is HP really hard on todays high performance regulators?
     
  4. Uncle Pug

    Uncle Pug Swims with Orca ScubaBoard Supporter

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    Should be the same price... call your local fire extinguisher service shop and ask.

    Yes... it is a good tank for those who will be mixing gases or want consistently good fills.

    You don't need to overfill a LP tank to get a good fill... the advantage of a HP is a smaller package.

    No, the HP is not really hard on todays regulators.

    It depends upon what you want.... and why you want it.
     
  5. bigcat

    bigcat Angel Fish

    # of Dives: 200 - 499
    Location: Kent, Ohio
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    What do you dive, LP or HP? Do you see a distinct advantage of one over the other?
     
  6. Uncle Pug

    Uncle Pug Swims with Orca ScubaBoard Supporter

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    I used to dive HP102 when I dove air. The LDS gave excellent fills but often overfilled to 4000 and let them cool down to 3700. That is not good.

    However we never could get good nitrox fills with the HPs so I went with the LP104s and eventually went to filling my own.

    Since I fill my own tanks it is very important for me to be using the LP tanks. My compressor fills the bank to 3500 with EAN32 and I can then fill my LP tanks off of that and get plenty of fills before hitting the bank again. I can overfill if I really need to but in reality I don't and sometimes when the bank is on the low side we only fill to 2200 and still have plenty of gas (doubles.)

    Also when I want to do some PP mixing it is beneficial to have the LP tanks... but I won't go into the details of that here in this forum.

    I personally like the length of the LP104 but it is a lot heavier than the HP102... especially when doubled up.... but for me that is not an issue.

    I just picked up 4 more LP104s yesterday.
     
  7. ericfine50

    ericfine50 DIR Practitioner

    # of Dives: 200 - 499
    Location: Grafton, MA
    1,385
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    LP is the way to go. You get better trim in the water and can always get good fills (Mixed Gas or Air). The hydro test with the + is slightly different, but the cost is the same.

    Eric
     
  8. bigcat

    bigcat Angel Fish

    # of Dives: 200 - 499
    Location: Kent, Ohio
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    You guys are killing me. I have a line on a nice new set of HP 100s. Maybe this is why they are so reasonably priced. Most negative comments I have read regarding HP tanks has to do with fills. This is not a problem for me. Don't understand the trim comment. Why do LP tanks give you better trim? :(
     
  9. The Chairman

    The Chairman Chairman of the Board

    # of Dives: I just don't log dives
    Location: Cave Country!
    57,630
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    There is nothing wrong with HP if you can get the fills... I know that I can, and I don't have a problem with them. Trim is fine!
     
  10. Uncle Pug

    Uncle Pug Swims with Orca ScubaBoard Supporter

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    Well if your name was littlecat it wouldn't be a problem....
    Shoot it may not be a problem anyway....
    But the HP is shorter than the LP....
    And puts its weight higher....
    Toward your head....


    So longer cats can use longer tanks.
     

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