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Thread: need formula

  1. #1
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    need formula

    Iím having brain lock on this one. I think it should be relatively simple.


    I have two discharges at two different concentrations.
    Discharge Q1 is at 30 gpm and discharge Q2 can vary.
    Discharge concentration Qw1 is 27,000 units and Discharge concentration Qw2 is 850 units.

    I would like to have a formula that would calculate the Q2 discharge so that the total discharge (Q1+Q2) has an average concentration of 10,000 units.

    Thanks.

  2. #2
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    Would this work for Q2 formula.....
    20,000-Q1

  3. #3
    WS Lounge VIP sdckapr's Avatar
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    If I understand what you are asking:

    =(Qw1-10000) * Q1 / (10000-Qw2)

    Logic:
    I think you want that:
    (Q1*Qw1 + Q2*Qw2) / (Q1 + Q2) = 10000

    So:
    (Q1*Qw1 + Q2*Qw2) = 10000 * (Q1 + Q2)
    Q1*Qw1 + Q2*Qw2 = 10000*Q1 + 10000*Q2
    Q1*Qw1 - 10000*Q1 = 10000*Q2 - Q2*Qw2
    (Qw1-10000) * Q1 = (10000-Qw2) * Q2
    Thus Q2 = (Qw1-10000) * Q1 / (10000-Qw2)

    Steve
    PS I get about 55.7 gpm...

  4. The Following User Says Thank You to sdckapr For This Useful Post:

    den239 (2011-02-24)

  5. #4
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    Steve:

    Works.
    Thanks for the brain unlock!

    John

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