Valve Dimension

=  Mains affected by the valve´s variable flow

To get the flow of 5 m³/h through the water heater´s primary side the pressure should be 10 kPa. Available pressure drop 100 kPa.
Calculate the K_υ-value of the valve and β

Solution:
P_υ = 100 - 10 = 90 kPa (0,9 bar)

K_υ = q /√∆p = 5/√0,9 = 5,27

K_υ = 5,27
(+40% =7,38; -20% = 4,2)

Valve Authority β
K_υ = 6,3
∆p_υ = (5/6,3)² = 0,63

β = 63/100 = 0,63 (bra β > 0,5)