Flow coefficient (Cv for control valve) is the capability of a valve to flow a liquid. One Cv is equal to a flow of 1 gallon per minute (gpm) of water at 60 degrees Fahrenheit with a pressure differential of 1 pound per square inch. The larger the Cv, the greater the flow in gpm. If you are dealing with a pressure differential other than 1 pound per square inch (psi), then gpm can be calculated in a few steps.
Determine the pressure differential of the valve by subtracting the downstream pressure from the upstream pressure.
Take the square root of the pressure differential.
Multiply the square root of the pressure differential by the valve coefficient to calculate the flow in gallons per minute.
About the Author
Logan Macomber is a staff writer for "The Caledonian Record," where he covers Vermont and New Hampshire sports. He has worked as director of imagery for Joyce Apps Limited, an iPhone application company. In 2012, Macomber achieved a Bachelor of the Arts in communication from Boston College, where he also minored in music and Irish studies.