Selected Cg (Flow Coefficiant) Maximum and Minimum

[CarlosEstinos]

Hello Everyone,

Im currently working on sizing some control valves. They are anti-surge valves. Im trying get my head around the flow coefficient and what it exactly means. When valves are being sized you are normally given values of CgMin CgMax. I also see a Selected Cg value.

What do these three coefficients tell me?

Thanks in Advanced

 

[TD2K]

Cg is a valve sizing parameter developed by Fisher (Emerson now). It's related to Cv by the equation Cg/C1 = Cv. For a lot of globe style valves, C1 is around 30.

 

[GHartmann]

The minimum and maximum Cg are conditions you specify that indicate:

The minimum valve flowing requirement of the application
The maximum valve flowing requirement of the application

The selected Cg is the Cg of the valve you have selected.

Anti-surge valves are tricky. They are usually oversized by factors of 1.5 to 2. You may want to look on the internet for guidence.