The flow factor is the metric equivalent of Flow coefficient.

In more practical terms, the flow factor Kv is the rate of flow of water in cubic metres per hour at a pressure drop of one kilogram per square centimetre across the valve.[1]

Kv is commonly used in Europe and Asia.

References

  1. ISBN 978-1-4005-2712-0 Flow of fluids through valves and fittings, Crane Co.
de:Kv-Wert