Cv for standard Globe Valves

[KevinNZ]

Hi does anyone know a source for Cv values for standard cast steel globe valves? My project is using 250NPS to 400NPS valves.

Thanks

 

[JimCasey]

manufacturer's literature is the only place that really matters.

If you estimate 15D^2 you won't be horribly wrong.
1":15
2":60
3":135
etc.

 

[Ashereng]

JimCasey is correct.

To get the Cv for a particular valve, you need to go to the manufacturer.

Oh, by the way, the Cv is more dependent on the port size than body size (yes, the body size also matters, but a bit less).

For a Fisher 1" D body:

Port Cv
1/4" 1.66
3/8" 4.03
1/2" 6.51
3/4" 12.3




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Albert Einstein
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[proinwv2]

The manufacturer determines the Cv by lab testing, usually to the ISA S75 standards.

I agree with the others, only obtain the information from the individual manufacturer. (I have many years experience in this.)

Paul

http://www.ostand.com

 

[KevinNZ]

Thanks

The valve sizes are 250 - 400mm.

The valves are standard isolation API 600 type globe valves, not control valves.

I can not find data from the manufactures. but since they are all the same pattern they maybe genic data avaible

cheers.

 

[KevinNZ]

Found it!

http://www.yps-valves.co.uk/reference/ASME_B1634_Catalogue.pdf

 

[davefitz]

If the valve is throttling a gas, you will also need to know the Xt as well as the Cv ( based on ISA nomenclature)to predict the flowrate.