kv FLOW FACTOR

 

The flow of a solenoid valve is the quantity of fluid per time unit flowing through the valve. It is this factor which determines its size.

In order use a simple formula to calculate and compare the different types of valves, all variables permitting the calculation of flow have been reduced to a common denominator: the flow factor kv. This factor depends on the design of the valve and the outlet tube size.

The kv factor given in this catalog have been set up according to the VDI/VDE 2173 standards at the following conditions :

 

 

 

 

 

 

 

 

 

 

 

 

 

For fluids, the flow factor is calculated as follows:

 

 

 

 

In practice, flow factor kv, is almost identical for a valve carrying water or oil up to a viscosity of 3°E. Beyond that limit, pressure flow specifications are modified; one should then take into consideration an adjustment factor C:

 

 

 

 

 

 

 

 

 

 

 

 

The calculation will lead to the choice of a valve with a higher flow factor value than the one which would have been chosen for a fluid with a viscosity inferior or equal to 3°E (Engler degrees).

Example : water at 20°C has a viscosity of 1 (cSt).

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

In the case of gases, the flow factors are calculated as follows:

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

The conversions of the flow factor coefficients are:

kv = 14.28 Cv (USA)

kv = 17.11 f (UK)

When several valves are assembled in parallel, the total kv is equal to: