Kvs – Meaning / Calculations
The Kvs value is a valve flow coefficient that 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:
LWhere:
- Q = flow in m³/h
- Kvs = valve flow coefficient
- ΔP = pressure drop across the valve in bar
Or, if you know the required flow:
Example: If you require 2.5 m³/h and want a valve pressure drop of 0.25 bar:
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 m³/h) and available differential pressure (kPa or bar) and I can calculate the required Kvs for you.