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Pressure drop in a water manifold

  1. Aug 23, 2010 #1
    Hi all,

    This is what I currently have.
    Water chiller with a flowrate of 2GPM (Choked to 2GPM)
    Ti= 50F

    It is a closed loop system. I am looking to split 1 line at 2 GPM (55-60psi) into 8 smaller lines that will run into my cooling jacket. All 8 lines are same length and size. The manifold I am thinking of using is this one, (http://www.mcmaster.com/#5469k171/=8j52d0). My main concern is that the pressure drop along the manifold is going to create nonuniform flow rates between the 8 lines.

    Manifold Inlet line is 3/8" ID and the manifold outlet lines are .17" ID.

    Thanks in advance,

    David Schlaud
  2. jcsd
  3. Aug 23, 2010 #2


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    Yes, that's a real possibility. What are you looking for?
  4. Aug 23, 2010 #3
    I am hoping to get some help or direction so that I can say mathematically that I have uniform flow. Or is it not even possible to have uniform flow in a manifold like the one I have noted without putting a valve in each line. Fluids is not my strong point.

    I plan on verifying experimentally but I would like to do calculations first to back up my theory/game plan.
  5. Aug 23, 2010 #4


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    If the length of your 8 lines is large compared to the length of the manifold (say more than 10 times) and assuming the 8 lines are identical in length and number of bends, and assuming the flow area of the manifold is at least 8 times larger than one of the tubes, then the flow through each of the tubes will be roughly the same.

    If the lines are different lengths, different elevations or number of bends, or if there is anything different about them at all, then they might have different flow through each. Basically, you want to add up the total restriction for each line and make sure they are equal.

    It's not easy to do the flow analysis without having some background in it. If you really want to try, you could go through the paper found on this link:

    ... but honestly, I wouldn't waste my time if unless you're really interested in learning how to do pipe flow analysis.
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