Kvs value is the flow coefficient of a valve and indicates how much water can pass through it when the valve is fully open.

The definition is:
Kvs = flow rate in m³/h through a fully open valve at a pressure drop of 1 bar, using water at roughly 5–40°C.

For example, a valve with Kvs = 4.0 passes about 4 m³/h (4,000 litres/hour) when the pressure drop across it is 1 bar.

For water, the useful formula is:

Where:
Q = flow in m³/h
Kvs = valve flow coefficient
ΔP = pressure drop across the valve in bar
Or, if you know the required flow:[/caption]

Where:
Q = flow in m³/h
Kvs = valve flow coefficient
ΔP = pressure drop across the valve in bar
Or, if you know the required flow:

So you’d be looking for a valve with a Kvs of approximately 5.0.
If you’re sizing an HVAC control valve, give me the required flow rate (l/s or m/h) and available differential pressure (kPa or bar) and I can calculate the required Kvs for you.