What is the CV factor of a valve and what is it for?

The CV factor of a valve is a coefficient that expresses the flow rate, in gallons per minute of water at 60º F, that passes through said valve when there is a pressure drop of 1 psi through it.

Once the flow rate that must circulate through a valve is known, the required CV can be determined and thus the appropriate valve can be selected. Or, given an available valve and its CV is known, the flow rate that will circulate through it can be calculated.

To perform these calculations, the formulas in the image are used (English version on page 2 of the following catalogue).