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Flow, pressure, and pipe diameter?

  1. Sep 19, 2014 #1
    If I have water being pumped through two lengths of pipe, both at 50 psi, but one pipe is 1.25" diameter and the other is 10" diameter, approimately how many gpm will be flowing through each pipe? Thanks in advance!
  2. jcsd
  3. Sep 19, 2014 #2

    Doug Huffman

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    Gold Member

    There is not enough information for an answer with absolute volume, but only relative volume rate.
  4. Sep 19, 2014 #3
    I can tell you that a 1.25" pipe will generally have a maximum practical flow of ~30-40 gpm and a 10 inch pipe will have a maximum practical flow of somewhere in the range of 2500-3000 gpm. However, each of these pipes can have any flow in between 0 and their maximum practical flow (and beyond, in some/many cases).

    If you want to know actual flow, you need to provide more information, at least:
    -inlet pressure (check)
    -outlet pressure
    -fittings? (valves, elbows, meters, etc)
    -elevation change?
    -Pipe material?
    -Fluid type? (water? Syrup?)
  5. Sep 24, 2014 #4
    Thanks guys. Those numbers are close enough for me to have made my point in a discussion..... the point being that 10 times the diameter is NOT 10 times the flow... :-) ...................especially when we already know that double the diameter is 4x the flow.....
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