Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Spring force

  1. Jul 4, 2008 #1
    I need to calculate the spring force required to make a back pressure regulator for fluid control the back pressure must exceed 3bar to open the ball valve the flow rate is 82mls/per min. the bore dia of the inlet is 2 mm dia. any help greatly appreciated
  2. jcsd
  3. Jul 4, 2008 #2


    User Avatar
    Science Advisor

    3 bar is 300000 N/m2 and your bore has an area of approximately 3.1 mm2= .00031 m2 so you are talking about a force of approximately 93 Newtons. The flow rate is irrelevant.
  4. Jul 4, 2008 #3


    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    Apply a freebody diagram to your sensing element, including poppet and spring. Diaphragm element area can be estimated by using the average diameter of backing plate diam and clamped diam at body. Don't forget to include poppet area as this is generally significant. Spring load then determines cracking pressure and 'droop'. You need to then determine valve lift above cracking pressure which produces a flow. Is that what you need? Are you familiar with calculating flow from Cv?
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook