1. PF Contest - Win "Conquering the Physics GRE" book! Click Here to Enter
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Horizontal ring water main pressure drop

  1. Feb 10, 2015 #1
    1. The problem statement, all variables and given/known data
    The accompanying figure shows a horizontal ring main consisting of a single loop of pipe, as might be used for supplying water to various points on one floor of a building. Water enters the main at A at 50 psig and is discharged at B and C at rates of 20 gpm and 60 gpm, respectively. Tests on the particular pipe forming the main show that the frictional pressure drop
    (psi) is given by –Δp = 0.0002Q2L, where L is the pipe length in feet and Q is the flow rate in gpm. Estimate the flow rates in the individual sections AB, BC and AC, and the pressures at B and C. The distances are AB = 100 ft, BC = 50 ft and AC = 200 ft


    3. The attempt at a solution
    I used the mechanical energy balance.
    I'm left with P1/rho=(P2/rho)+hf
    hf= Pipeline + Minor Losses
    hf= Pipeline + 0
    Pipeline= ((4fL)/D)*(Velocity^2)/2
    mass flow= 80 gpm
  2. jcsd
  3. Feb 11, 2015 #2


    User Avatar
    Science Advisor
    Homework Helper
    2017 Award

    As far as I can oversee this, the place of your ((4fL)/D)*(Velocity^2)/2 is taken by the given –Δp = 0.0002Q2L, right ?

    Now try and approach this a bit more systematically: you have some givens, you have some equations (you do, I suppose, even though part 2 from the template has mysteriously disappeared ?) and you have some unknowns. Work towards setting up N equations with N unknowns, then solve them.

    And make (also for yourself) a list of symbols you use. P1 ? P2 ?
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted