# Valve Cracking Pressure

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 January 11, 2016, 09:52 Valve Cracking Pressure #1 New Member   Join Date: Nov 2015 Posts: 10 Rep Power: 10 Hi everybody! I'd like to evaluate the cracking pressure (which is the minimum upstream pressure to open the valve) of a swing check valve by means of an analytical method and a CFD analysis. The disc has to open of a small distance. Any suggestions? Thanks!!

 January 11, 2016, 13:11 #2 Member   Kaya Onur Dag Join Date: Apr 2013 Posts: 94 Rep Power: 13 assuming spring has a constant torque T, and the length between the center of the valve and the spring position is x, so you need flow pressure to generate F = T*x much force on the valve. If the area on the valve is A then you need the static pressure of P > F/A from the flow to open the valve. I don't think you need a cfd computation to find P since the flow is going to be creeping flow at the pressure which is just enogh to open the valve. I am not sure why you consider CFD for such problem

 January 11, 2016, 17:11 #3 New Member   Join Date: Nov 2015 Posts: 10 Rep Power: 10 First of all T=F*x. Then there is no spring, only the weight of the disc, let's assume it 2kg for example. It is different, do I have to impose a small angle of rotation (1-2°), just the minimum to make flow pass? Do I have to impose a balance to rotation?

 January 11, 2016, 17:27 #4 Member   Kaya Onur Dag Join Date: Apr 2013 Posts: 94 Rep Power: 13 you're right. to me if there's no spring than any pressure greater than the ambient will make the disk / valve open considering that the center of gravity is aligned with the hinge.

 January 12, 2016, 02:33 #5 New Member   Join Date: Nov 2015 Posts: 10 Rep Power: 10 Unfortunately the solution is different.

 Tags cfd, chack, cracking, pressure, valve