What is Valve Flow Coefficient (Cv)?

Valve Flow Coefficient (Cv) is a valve’s capacity for a liquid or gas to flow through it.  Basically, the larger the opening in a valve, the larger the Cv.  As a valve is opened more and more, the Cv increases until the valve is fully open, where it reaches its highest possible Cv, or 100% open Cv. See flow curve chart below. The fully open Cv (100% open) for this valve is 52.


Cv is technically defined as:  The volume (in US gallons) of water at 60°F that will flow per minute through a valve with a pressure drop of 1 psi across the valve.

For determining what size valve should be used for a particular application, Cv can be calculated using the sizing program at https://kimray.com/sizing, then a list of applicable valves is displayed, based on the calculated Cv.