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Cylinder capacity table errors?

Discussion in 'Basic Scuba Discussions' started by DivingColeridge, Nov 27, 2020.

  1. DivingColeridge

    DivingColeridge Divemaster

    # of Dives: 100 - 199
    Location: Christchurch
    53
    26
    18
    IMG_20201128_172545.jpg

    This table is from the encyclopedia of recreational diving. (rev 01/17 version)

    I don't understand how they calculated the full capacities for the hp cylinders at the bottom (specifically the metric values) did they use 300 bar instead of 327 by accident? Also how would the smaller cylinder have a larger capacity for the same rated pressure (2nd row from the bottom)

    All in all this table has me very confused and pretty sure there are some errors in here somewhere.
     
  2. tursiops

    tursiops Marine Scientist and Master Instructor ScubaBoard Supporter

    # of Dives: 2,500 - 4,999
    Location: U.S. East Coast
    10,778
    8,579
    113
    I would not use that table. It has a number of errors in it. For example, it says an AL80 holds 80 cuft at 3000 psi. Not.
    Use, for example, https://huronscuba.com/equipment/scuba-cylinder-specifications.
    What else is confusing about your table is the various cylinders are made by different companies, and the names ("120") are a bit arbitrary.
    That table is really meant to show how to go back and forth between metric and imperial. Too bad it has never been checked.
     
  3. DivingColeridge

    DivingColeridge Divemaster

    # of Dives: 100 - 199
    Location: Christchurch
    53
    26
    18
    Thanks for that table, it's quite useful. I've been finding a few errors in this table
     
  4. tursiops

    tursiops Marine Scientist and Master Instructor ScubaBoard Supporter

    # of Dives: 2,500 - 4,999
    Location: U.S. East Coast
    10,778
    8,579
    113
  5. DivingColeridge

    DivingColeridge Divemaster

    # of Dives: 100 - 199
    Location: Christchurch
    53
    26
    18
  6. VikingDives

    VikingDives Mostly Harmless ScubaBoard Sponsor

    # of Dives: I'm a Fish!
    Location: New Mexico
    108
    57
    28
  7. Angelo Farina

    Angelo Farina Marine Scientist

    # of Dives: 1,000 - 2,499
    Location: Parma, ITALY
    1,582
    2,396
    113
    Why not simply multiply the liters by the bars? Both are stamped over the tank here...
    The liters are always exactly what is stamped, the bars are better read from your SPG...
     
  8. Angelo Farina

    Angelo Farina Marine Scientist

    # of Dives: 1,000 - 2,499
    Location: Parma, ITALY
    1,582
    2,396
    113
    Example: a 10-liters tank at 200 bar holds 2000 liters
    Another: a 15 liters tank at 232 bar holds 3480 liters
     
  9. VikingDives

    VikingDives Mostly Harmless ScubaBoard Sponsor

    # of Dives: I'm a Fish!
    Location: New Mexico
    108
    57
    28
    Not exactly, it's a little more nuanced than that. You might want to check the link I posted above.

    Ideal Capacity = Cylinder water volume * pressure / atmospheric pressure. Then there's air temps, and cylinder temps. . . And then there's compressibility of the gas...
     
  10. JMBL

    JMBL Solo Diver

    # of Dives: 1,000 - 2,499
    Location: France
    678
    315
    63
    Ok, but what the use how calculating that way ? I'm not trolling here, I'm just curious.
     

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