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Pressure in a 2" pipe branching into four 1" pipes

  1. Oct 8, 2018 #1
    Hello all,
    I am an Electronics Engineer, working in an R&D Organisation specializing in Electronics and Advanced Computing. My area of work is Control & Instrumentation related to Industrial Automation.

    I am trying to identify the a solenoid valve to be used on a 2" pipe. For this I need to know the pressure in the pipe.
    Water flowing in a pipe of 2" diameter is branching into 4 pipes having 1" diameter. At the output of the 4 pipes there is a sprinkler, which works at a pressure of 120 psi. The main pipe is connected to a pump having 10 HP motor. i.e. Water pumped from a 10 HP Pump flows through a 2" diameter pipe and branches into 4 pipes of 1" diameter before flowing out through sprinklers.

    I would like to know the pressure in the 2" Main Pipe.

    Thanks in advance.
    Senju Panicker
  2. jcsd
  3. Oct 8, 2018 #2


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    Hello Senju, :welcome:

    Here at PF we always encourage some poster initiative. Did you google a few things ? If so, what popped up ?

    Your question doesn't constitute a complete problem statement: pipe lengths, flow rates, geometry ?
  4. Oct 8, 2018 #3
    And pump characteristics (flow vs head), sprinkler characteristics (orifice size, dP vs flow), probably more info once an analysis begins.
  5. Oct 8, 2018 #4


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    If this is a real sprinkler system and 120psi is the in operation pressure (that would be a lot - is it static?), the piping loss is unlikely to add significantly to that.

    ...however if this is more than an academic exercise, you're likely required to do a full fledged hydraulic calc and get it stamped by a professional engineer.
  6. Oct 11, 2018 #5
    If you are looking for a proper calculation you will have to make a drawing/sketch with exact lengths of each pipe. The height at the beginning and end of each pipe should be indicated
    Any bends, valves etc will have to be indicated.
    If you can supply the pump curve that would be very useful. Alternately you can supply the pump type or model number and somebody might have it(unlikely).
    What you have described can be anything from a irrigation system for small farm or greenhouse to a fire reticulation system for a small hotel. It's difficult to give you proper advice.

    If you want to know the pressure at an exact point the best thing to do is to install a pressure gauge. Calculations are estimates. A pressure gauge is an actual measurement. It's good practise to have a pressure gauge at the outlet of a pump anyway so I think this is the best route.
    Last edited: Oct 11, 2018
  7. Oct 11, 2018 #6


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    @Senju Panicker was last seen monday 11:20, so he/she hasn't even see the first response....
  8. Oct 11, 2018 #7
    Yeah well. It's obviously not that urgent. He'll show up sooner or later though.It's all chill...
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