Control valves questions and answers

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1. What is CV?

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Cv is the Valve Coefficient, and is a measure of the capacity of a valve, which takes account of its size and the natural restriction to flow through the valve. Using published formulae it is possible to calculate the Cv required for an application. By comparing this calculated value with the Cv capacities of different valves it is possible to select a suitable size and type of valve for the application.

Common Definition of CV :

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The Cv of a valve is the quantity of water in US gallons at 60 °F that will pass through the valve each minute with a 1 psi pressure drop across it. 

The Kv value is the metric equivalent in m3/hr with 1 bar pressure drop.

The capacity of each valve can be expressed in terms of Cv - the value being determined experimentally in most cases. Using formulae developed empirically it is possible to calculate a Cv requirement for an application. By comparing the two figures it is possible to select the correct size of valve for the application.

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