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How much air does an LP85 hold at 2400 PSI?

Discussion in 'Tanks, Valves and Bands' started by CaveSloth, Sep 23, 2019.

  1. CaveSloth

    CaveSloth Nassau Grouper

    # of Dives: 50 - 99
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    My Faber LP85 has a little sign near the valve that says 2400. How much does this tank hold when filled to 2400 PSI? What about when overfilled to 3600 PSI?
     
  2. rjack321

    rjack321 Captain

    # of Dives: 1,000 - 2,499
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    85cf at 2640

    The tank factor of an lp85 is just over 3cf/100psi. 3.2 actually
    85/26.40 = 3.2cf per 100psi
    24 * 3.2 = 76.8cf
    36 * 3.2 = 115cf

    Roughly and will depend a little bit on the exact gas because of compressibility issues with helium.
     
  3. Lorenzoid

    Lorenzoid idling in neutral buoyancy

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    Wouldn't that be "2640"? Ten percent of 2400 is 240, so 2400+240 = 2640.
     
  4. rjack321

    rjack321 Captain

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    Sorry fat fingered that. yes 2640. although 10psi doesn't matter in the end.. And I did it twice so I fixed that lol
     
    Lorenzoid likes this.
  5. CaveSloth

    CaveSloth Nassau Grouper

    # of Dives: 50 - 99
    Location: The Deep South
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    My tanks say the following:

    FABER MADE IN ITALY M8303 04/1871/ 198
    TC-3AAM-184/DOT-3AA 2400 REE 66

    What all that mean and what is my personal "tank factor"?
     
  6. tursiops

    tursiops Marine Scientist and Master Instructor ScubaBoard Supporter

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    Without the unnecessary nonsense of tank factors, if the tank holds 85 cuft at 2640, then it holds
    (2400/2640) * 85 = 77 cuft at 2400 and (3600/2640) * 85 = 116 cuft at 3600. Simple proportions, at least for an ideal gas, which tanks factors don't accommodate anyway.
     
    kelemvor, StefinSB and rongoodman like this.
  7. Lorenzoid

    Lorenzoid idling in neutral buoyancy

    # of Dives: 500 - 999
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    "Tank factor" is a term used to describe the ratio between pressure and volume for any given tank. In other words, how many cubic feet per psi does it hold. For convenience of doing calculations, tank factor is generally expressed in cubic feet per hundred psi.
     
    Compressor likes this.
  8. rjack321

    rjack321 Captain

    # of Dives: 1,000 - 2,499
    Location: Port Orchard, WA
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    "tank factors" are just a way to use the same ratio to explain how algebra can be used to figure out the volume at any pressure


    M8303 is a code for Faber
    04/1871/198 is the serial number
    TC3AAM-184 is Transport Canada 3AA standard, metric pressure of 184 bar
    DOT-3AA 2400 is US Dept of Transportation 3AA standard 2400 psi
    REE is reject elastic expansion in milliliters - used by the hydroshop

    The volumes for your tank at the pressures you asked about are above. Along with the algebra to calculate the volume at any pressure.
     
    Compressor and seeker242 like this.
  9. CaveSloth

    CaveSloth Nassau Grouper

    # of Dives: 50 - 99
    Location: The Deep South
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    Then I looked more and found another marking:

    09 * 04 +
     
  10. CaveSloth

    CaveSloth Nassau Grouper

    # of Dives: 50 - 99
    Location: The Deep South
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    I was asking what is the factor for my personal tanks.
     

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