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Weighed some tanks at various PSIs and got unexpected results.

Discussion in 'Basic Scuba Discussions' started by CaveSloth, Oct 16, 2019.

  1. CaveSloth

    CaveSloth Barracuda

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  2. FreeFlyFreak

    FreeFlyFreak Solo Diver

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    @CaveSloth
    The last post in the thread I linked to earlier has some data that came from one Aluminum tank manufacturer:

     
  3. RayfromTX

    RayfromTX Student Of Gas Mixology Staff Member ScubaBoard Sponsor

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  4. RayfromTX

    RayfromTX Student Of Gas Mixology Staff Member ScubaBoard Sponsor

    # of Dives: 100 - 199
    Location: Hill Country of Central TX
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    lp85 = 13L
    13*2640/14.696=2,335L
    2,335L = 82.5 cu ft / 1.0173(z factor) = 81.1 cu ft actual
    13*3750/14.696=3,317L
    3,317L = 117 cu ft / 1.075(~z factor) = 109 cu ft actual

    That gets you part of the way to your delta. Temps can be a pretty big factor. These numbers assume 70f and air.
     
  5. CaveSloth

    CaveSloth Barracuda

    # of Dives: 50 - 99
    Location: The Deep South
    221
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    Alright then, sounds like temps and possibly instrument precision errors could account for the discrepancy. So, sounds like our tanks probably aren't deficient?

    Also, what is really important for me to know is how many minutes of breathing can I personally get out of 100 PSI at a given depth with a given tank, not exactly how much air it can hold.
     
  6. runsongas

    runsongas Great White

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    what is the accuracy of the scale in question and operating range? when was it's last calibration?
     
  7. rhwestfall

    rhwestfall Solo Diver

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    SAC
     
  8. rhwestfall

    rhwestfall Solo Diver

    # of Dives: 200 - 499
    Location: "La Grande Ile"
    12,271
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    One of these is pretty cool if you are math challenged...

    upload_2019-10-16_14-28-8.png

    Shame they stopped making them.
     
    TTPaws and drjtprice like this.
  9. Degenerate

    Degenerate DIR Practitioner

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    So much this.
    Did OP use a regular bathroom scale type of scale, because if so that number might differ a fair bit from the real truth.
     
  10. CaveSloth

    CaveSloth Barracuda

    # of Dives: 50 - 99
    Location: The Deep South
    221
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