# Valve sizing calculator

The Kv-value is a measure of the flow rate through a valve for a given medium and pressure drop. The larger this value, the higher the flow rate through the valve will be at a given pressure drop. Usually, the Kv-value is given in the product description or datasheet. It provides a more accurate indication than for example the pipe connection size or orifice diameter. The Kv-value is measured as the flow rate of water in m3/h with a pressure drop of 1 bar at 20°C.

If the medium characteristics, the pressure drop and the desired flow rate are known, the minimal required Kv-value for the valve can be calculated. Different formulas apply for fluids and gases.

## Kv-value calculator fluids

Fill a value for the inlet pressure, the outlet pressure and the minimal required flow rate. Click calculate and the Kv and Cv value will be calculated. Choose a valve with a Kv-value equal or higher than the calculated value.

Liquid:
Specific gravity:
Inlet pressure:
Outlet pressure:
Flow rate:

Valve Kv value:
Valve Cv value: where:
Q  Flow rate[m3/hour]
Kv  Hydraulic factor
dp  Pressure differential [bar]
SG  Specific Gravity (Water 1)

## Kv-value calculator gases

Choose a gas type and the inlet temperature. Choose the inlet pressure, the outlet pressure, the required flow rate and click calculate. Choose a valve with an equal or higher Kv-value to achieve the desired flow rate. The N in the flow rate stands for normal conditions (atmospheric pressure and 0 degrees Celsius).

Gas:
Specific gravity:
Air temperature:
Inlet pressure:
Outlet pressure:
Flow rate:

Valve Kv value:    where:
QN: Normal Flow rate [m3/hour]
Kv : Hydraulic factor
T : Inlet gas temperature [K]
p1  Inlet Pressure [bar]
p2  Outlet Pressure [bar]
dp  Pressure differential [bar]
SG  Specific Gravity (Air  1)