What is co-efficient (CV) of control valve

                                    

       Valve sizing coefficient ‘Cv’ is defined as the number of US gallons per minute of water that will pass through a given restriction with a pressure drop of one psi.

This is basic equation for liquid calculations, in volumetric flow  Where -

Q  -  flow rate in US gpm

P1 -  upstream pressure in psia

P2 - downstream pressure in psia

G  -  liquid specific gravity @ flowing temp.