1. Not finding help here? Sign up for a free 30min tutor trial with Chegg Tutors
    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!

Calculating drop in gas pressure

  1. Feb 5, 2013 #1
    Poles Formula (see page 10 of attachment)

    www.mech.hku.hk/bse/MEBS6000/mebs6000_1011_04_steam.pdf [Broken]

    Where have I gone wrong?

    • q = flow (m3/h)
    • d = diameter of pipe (mm)
    • h = pressure drop (mbar)
    • l = length of pipe (m)
    • s = specific gravity of gas (density of gas / density of air)

    h = ( q^2 * s * l ) / ( 0.0071^2 * d^5 )

    q = 6 m3/h
    d = 20mm
    l = 19M
    s = 0.58

    The result is 2.459 i.e. the pressure drops by 2.2459 mb, which on the face of it looks fine, the problem is that if I reduce the flow rate the loss of pressure over the length of the pipe drops. Which in theory means that if I start with 21mb gas pressure and have a lower flow rate I end up with a higher pressure at the end of the pipe; that can't be right can it?
     
    Last edited by a moderator: May 6, 2017
  2. jcsd
  3. Feb 5, 2013 #2

    russ_watters

    User Avatar

    Staff: Mentor

    Yes, that is correct. Higher flow causes more friction and more pressure loss.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Calculating drop in gas pressure
  1. Pressure drop (Replies: 7)

Loading...