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Thread: Conversion of Cylinder sizes

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    New Member Simon Ciantar is an unknown quantity at this point Simon Ciantar's Avatar
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    Conversion of Cylinder sizes

    Hi all,

    To begin posting on this forum I decided to tackle a very simple subject but which bugs me when trying to follow some treads here

    How do you convert cubic feet to litres ?as most of you guys seem to use this unit when talking on cylinder capacity Im used to using 10, 12 , 15 ltr cylinders etc...

    thks

    Simon

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    Re: Conversion of Cylinder sizes

    Short version; 1 liter = 0.035 314 667 cubic foot

    Long version. Take Metric tank, multiple capacity (ie 12L) by pressure (ie 232 bar), to get Litres of free gas (2784 in this case). Multiple by 0.035314667 to get the US equivalent; 98 Cuft (give or take small change).

    Obviously in the other direction you take the cuFt/0.035 etc then divide by rated pressure. For a standard alu 80 (runs at 3000 PSI/207 Bar);

    (80/0.035314667)/207=10.9 Liter.


    /Zak
    Last edited by EBT; 14th January 2006 at 11:52.

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    Re: Conversion of Cylinder sizes

    Quote Originally Posted by Simon Ciantar
    How do you convert cubic feet to litres ?
    This is a rough calculation...
    • Convert cf into free liters using: cf * 28.3 = free liters
    • Convert rated pressure into bar using: psi / 14.5 = bar
    • Convert free liter at pressure into displacement: free liter / bar = L
    For example, 80cf 3200psi into Metric equivalent:
    • 80cf * 28.3 = 2,264 free liters
    • 3200psi / 14.5 = 220 bar
    • 2264 free liters / 220 bar = 10 L
    As said, just roughly... ;)
    Last edited by decoweenie; 14th January 2006 at 12:34. Reason: spell it out

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    New Member macdiver is an unknown quantity at this point macdiver's Avatar
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    Re: Conversion of Cylinder sizes

    Is there a table somewhere that gives equivalent tank sizes typically used in discussions (e.g. al 2 liter = 13 cu ft )? The above conversion factors are great for calculating accurate numbers but I usually see 2, 3, 7, 10, 12, and 15 liter tanks mentioned not 11. So is the above a 10 or a 12? or is it an 11 that just isn't as common?

    edited due to typo

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    Re: Conversion of Cylinder sizes

    Alternatively try the Gas Management Program (GMP)

    Should be available at:-

    GMP

    Does all this simple sort of stuff as well as blending calculations.

    A spot on piece of software..


    Rgds

    Mark

    .

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    Re: Conversion of Cylinder sizes

    Quote Originally Posted by macdiver
    Is there a table somewhere that gives equivalent tank sizes typically used in discussions (e.g. al 2 liter = 13 cu ft )? The above conversion factors are great for calculating accurate numbers but I usually see 2, 3, 7, 10, 12, and 15 liter tanks mentioned not 11. So is the above a 10 or a 12? or is it an 11 that just isn't as common?
    Part of the problem is that different tank pressures are common in the US (usually lower). A 3 liter tank here has 19 or 20 cuft, whereas in Europe you can get some with 29 cuft.

    Then different materials and wall thicknesses. The same size tank in alu or steel will have different liquid capacity (L) ... and maybe pumped to a different fill pressure. And there are overpressure fills (+ rating in US) ... .

    Last but not least, 80 cuft doesn't mean that you can actually get 80 cuft into the tank. Here in the US vendors liberally round up sizes. Said tank usually holds 77.4 cuft.

    If you look at manufacturer's or distributor's websites for US tanks you'll frequently find the liter capacity listed.

    Rough guide:
    steel/alu 13 cuft = 2 L
    steel/alu 19 cuft = 3 L
    steel 27 cuft = 4 L
    steel 45 cuft = 7 L
    steel 66/72 cuft = 10 L
    steel 98 cuft = 15 L
    steel 131 cuft = 20 L

    PITA like everything else they measure here.

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    RBW Member leadking is on a distinguished road leadking is on a distinguished road leadking's Avatar
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    Re: Conversion of Cylinder sizes

    liters is the liquid internal volume of a cylinder (61 CI or .053 CF)

    U.S. measurement are total CF of gas at maximum rated pressure. In the case of 3AA cylinders include the 10% overfill.

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    Re: Conversion of Cylinder sizes

    OMS shows their steel cylinder conversions as follows:

    Air capacity (cuft) - Liquid capacity (L)
    130cuft - 17L
    100cuft - 13L
    80cuft - 10L
    65cuft - 8L
    45cuft - 7L

    http://www.omsdive.com/cyl_spec.html

    Westwinds.

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    New Member Simon Ciantar is an unknown quantity at this point Simon Ciantar's Avatar
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    Re: Conversion of Cylinder sizes

    thks folks

    that pretty much what I was after


    Simon

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    Re: Conversion of Cylinder sizes

    I have used the conversion formula given here cuFT/0.035/rated pressure,but I don't understand that a tank with lower pressure holds more liters? Example: a 95 steel tank with 2400psi(165.474bar) holds 16.40 liters.
    same tank at 2650 holds 14.85 liters according to this formula. How can this be?

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