Flow Coefficient Kva (valves)

[zoon]

The flow coefficient Kvs is the actual or stated Kv value of a particular valve when fully open. What is the flow coefficient Kva?

 

[Tremolo]

Zoon,

I usually see the flow coefficient for a valve represented by the symbol Cv, so I googled Kvs and found a decent link:

http://www.eurotherm.com/products/valves/size_water.htm

This link states that Kvs is the metric equivalent of Cv. Specifically, the link states that Kvs is the flow m^3/hr per 1 bar (100 kPa) pressure difference. Flow can be calcualated as,

m^3/hr = kvs * sqrt(dP)

where dP is the pressure difference in bar.

Are there any units for your Kvs values?


I have also seen the equation written as

m^3/hr = kvs * sqrt(dP * rhoref/rho)

to account for fluids at different temperatures where rhoref is the cold water reference density (1000 kg/m3) and rho is the actual water density.