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Valve Cracking Pressure

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Old   January 11, 2016, 09:52
Default Valve Cracking Pressure
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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!!
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Old   January 11, 2016, 13:11
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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
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Old   January 11, 2016, 17:11
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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?
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Old   January 11, 2016, 17:27
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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.
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Old   January 12, 2016, 02:33
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Unfortunately the solution is different.
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