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Thread: how to calculate the O2 drop

  1. #1
    RBW Member mrdall is an unknown quantity at this point mrdall's Avatar
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    Hyperion

    how to calculate the O2 drop

    Hi I am trying to make an App fore Android mobile, to calculate the O2 drop in the loop

    but I cant find the formula to calculate this :-(

    from an erligere treath here on rb world I got this.

    Reb PpO2 = (FO2*((K*Vol Ratio*ATA)+1)-1)/(K*Vol Ratio)

    but there must be some error lets look at )+1)-1) this is equal nothing

    lets try to put some data in

    Depth (pressuer) 21meter = 3,1bar
    O2% in gas = 0,32
    DUmp Ration 1:10 = 0,1
    lung volume = 4,5L
    AMV (L/min) = 23
    Metabolism O2 (L/min) = 1,0
    K = AMV * Metabolism = 23

    Reb PpO2 = (FO2*((K*Vol Ratio*ATA)+1)-1)/(K*Vol Ratio)
    whar is Vol Ration (maybe Lung Value * Dump Ration = 0,1 * 4,5 = 0,45)
    and if the FO2 is the same as "O2% in gas" the we can fill the number in.

    Reb PpO2 = (0,32*((23*0,45*3,1)+1)-1)/(23*0,45)
    Reb PpO2 = (0,32*(32,085)/10,35
    Reb PpO2 = 10,2672/10,35
    Reb PpO2 = 0,992

    if I put the same number into Maxim's pc program, I end up whit 0,70 PPo2

    I hawe reyed whit other formula, that I have found on the inter net, the SF1 manual and so on, but so fare, I have not been able to come up whit a formula that is working :-(

    can some of you help me pleas -)

    best regards Morten

  2. #2
    RBW Member edmundfennema is an unknown quantity at this point edmundfennema's Avatar
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    Re: how to calculate the O2 drop

    Don't know anything about RB's but a little about maths...

    This is where it goes wrong:
    Quote Originally Posted by mrdall  View Original Post
    but there must be some error lets look at )+1)-1) this is equal nothing
    so:
    Quote Originally Posted by mrdall  View Original Post

    Reb PpO2 = (0,32*((23*0,45*3,1)+1)-1)/(23*0,45)
    Reb PpO2 = (0,32*(32,085)/10,35
    should be:
    Reb PpO2 = (0,32*((23*0,45*3,1)+1)-1)/(23*0,45)
    Reb PpO2 = (0,32*((32.085)+1)-1)/(10.35)
    Reb PpO2 = (0,32*33.085-1)/(10.35)
    Reb PpO2 = ((10.5872)-1)/(10.35)
    Reb PpO2 = (9.5872)/(10.35)
    Reb PpO2 = 0.926299517

  3. #3
    RBW Member mrdall is an unknown quantity at this point mrdall's Avatar
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    Hyperion

    Re: how to calculate the O2 drop

    Quote Originally Posted by edmundfennema  View Original Post
    Don't know anything about Rebreather's but a little about maths...

    should be:
    Reb PpO2 = (0,32*((23*0,45*3,1)+1)-1)/(23*0,45)
    Reb PpO2 = (0,32*((32.085)+1)-1)/(10.35)
    Reb PpO2 = (0,32*33.085-1)/(10.35)
    Reb PpO2 = ((10.5872)-1)/(10.35)
    Reb PpO2 = (9.5872)/(10.35)
    Reb PpO2 = 0.926299517
    tank, but still end up whit 0,93 and the plane was to end up whit 0,70
    so there is still some thing wrong whit the formula

    can any other help.

    best morten

  4. #4
    RBW Member gtzavelas is a glorious beacon of light gtzavelas is a glorious beacon of light gtzavelas is a glorious beacon of light gtzavelas is a glorious beacon of light gtzavelas is a glorious beacon of light gtzavelas is a glorious beacon of light gtzavelas is a glorious beacon of light gtzavelas is a glorious beacon of light gtzavelas is a glorious beacon of light gtzavelas is a glorious beacon of light gtzavelas is a glorious beacon of light gtzavelas's Avatar
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    Megalodon

    RB80 Clone, CastoroC96, RGU

    I have an XLS file with the formula in my office PC.
    PM me you email and I will send it tomorrow .

    It's correct & confirmed ( I cross checked it with a ppO2 Meter when I used to dive my pSCR )

  5. #5
    RBW Member mrdall is an unknown quantity at this point mrdall's Avatar
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    Hyperion

    Re: how to calculate the O2 drop

    Quote Originally Posted by gtzavelas  View Original Post
    I have an XLS file with the formula in my office PC.
    PM me you email and I will send it tomorrow .

    It's correct & confirmed ( I cross checked it with a ppO2 Meter when I used to dive my pSCR )
    cool, tank a lot, PM is send.

    Best Morten

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  7. #7
    TRITON Dive Team, Serbia danijeladir is an unknown quantity at this point danijeladir's Avatar
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    pSCR Satori

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    Re: how to calculate the O2 drop

    Kv*Ratio*Ata then +1
    then *FO2
    than -1
    and at the end divide with Kv*Ratio
    I can not manage to write it more nice (math stile) on the computer.

    At the end you will get the right result.

    Hope this helped
    regards Mirko

    p.s. The O2 drop is of course a little more complicated...

  8. #8
    RBW Member mrdall is an unknown quantity at this point mrdall's Avatar
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    Re: how to calculate the O2 drop

    hi,

    tank you all fore your input, I got the formula to work now, so now I am working on my Android App

    best regards Morten

  9. #9
    RBW Member anarchista is an unknown quantity at this point anarchista's Avatar
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    Re: how to calculate the O2 drop

    Quote Originally Posted by mrdall  View Original Post
    Reb PpO2 = (FO2*((K*Vol Ratio*ATA)+1)-1)/(K*Vol Ratio)
    This type of calculation is good, for a long time (steady state). When changing the depth of a few minutes, this value is reached. With greater effort faster. Replacement of the mixture without washing the circulation, at depths greater or important than the OC is another level of expertise.

    rc greet

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