Valve Leakage

[kjvaughn]

What is the best way to calculate valve leak-by rate in a angle control valve? The data that is available to me is upstream pressure at different valve positions, downstream pressure, upstream temperature, and the information on the valve, such as Cv and other technical stuff.

I am trying to figure out the estimated leak-by rate for this valve, but have no idea and keep going in circles. I am not even sure if it is possible.

 

[bimr]

If you suspect the valve is leaking replace it. You can also remove the valve and bench test it.

 

[danw2]

comments on valve leakage at

http://www.svf.net/pdf/Class_VI.pdf

http://www.maintenanceresources.com/ReferenceLibrary/ControlValves/CashcoSeatLeakage.htm

http://www.contractorsunlimited.co.uk/toolbox/valve-leakage.shtml

 

[JLSeagull]

New -- an angle control valve may have Class II leakage. This would permit leakage of 0.5% of the valve capacity.

Once placed in service assume that the FCI 70-2 leakage classes are VERY optimistic compared to the actual leakage.

 

[proinwv2]

JLSeagull said, "Once placed in service assume that the FCI 70-2 leakage classes are VERY optimistic compared to the actual leakage."

This is very true. The FCI test is for a new valve, usually tested at the manufacturers facility and to one specifice test procedure.

Unfortunately, valves do leak. The only disagreement should be how to measure and evaluate it.

Paul Ostand

http://www.ostand.com