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Water Flow, Mass Flow through 5 Gallon Jug

  1. Apr 6, 2012 #1
    Here is the run down first, I'm trying to find a min mass flow rate for my project which needs to be 1 GPM, and max 4 GPM. Now water is going out of a 5 gallon jug, that has the top cut off, and the water is flowing into a PVC pipe. The area is already set at 1.5 inches, which I know is to big. I need to find the velocity of water at atm pressure, and then the diameter of the circle which the water will funnel through. I did some work I just need help making sure I did it right, basically a check over. think of it as a Deer Park 5 gallon bottle, like the ones for water dispenser, but the top cut off, and it flowing out the nozzle.

    Man how do I use the Latex thing?

    So, I know V=[itex]\sqrt{2*19.5 inches * 387.6 inches/s^{2}}[/itex]
    V=122.95 inches/sec, 10.245 ft/s = 614.7 ft/min

    Now the simple equation of Q=VA

    1 GPM->.13[itex]ft^{3}[/itex]/min = 614.7ft/min * A
    .03024 in^2 = A(min)
    sqrt(.03024/∏)= r(min) = .09811 inches

    We would have to reduce our inner diameter to .19622 inches.
    Now is this right? I can't believe that? I was initial thinking it would be a DE since our mass flow would be varying, depending the height of the water, gravity would be pushing it through the main system.
  2. jcsd
  3. Apr 7, 2012 #2


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    Staff: Mentor

    A sketch would help to understand your calculations.
    In addition, SI units would make unit conversions much easier.

    Based on your description of your system, I think this is true. Probably your 19.5 inches would vary.
  4. Apr 7, 2012 #3
    mass flow.jpg

    gravity will force the water through the tank and I need to figure out what the diameter will be, to get 1 gpm.
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