spring force

mkelly

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

HallsofIvy

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.

Q_Goest

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?