Why is the Kv value not suitable for designing control valves?

The Kv value is the volume flow of a medium per time unit with a pressure drop of 1 bar at a specific temperature.

In practical terms this means that it is only possible to make a statement on the flow rate at a specific opening degree of the valve. However, no statement can be made about how a valve performs or the linear control characteristic.

In order to construct a valve properly, statical / dynamic pressure losses with the valve and the pipeline, minimum and maximum flow rates and the flow velocity must always be taken into account. It is only when this data is available that control valves can be designed in such a manner that they show a linear control characteristic and operate permanently outside the cavitation range.