t-NEXT DF DX
T_tNEXTDFDX_0719_EN
86
MEHITS S.p.A.
DATA BOOK
VALVE PRESSURE DROP CALCULATION AS FUNCTION OF WATER FLOW RATE
Flow coefficient kv defines the water flow (between 5°C and 40°C) expressed in m
3
/h that cross a valve with a pressure drop of 1bar (100kPa).
With this data is possible to calculate the localized pressure drop as function of the water flow rate.
P = (Q / kv)
2
P (bar) = localized pressure drop of valve;
Q (m
3
/h) = water flow rate
–
it varies according to the desired operating condition;
kv
(m
3
/h) = valve flow coefficient.
The formula allows to calculate the value of the localized pressure drop (in bar).
The pressure drops values showed on the documentation are supplied in kPa.
Is possible to change from one unit to another through the following conversion.
1 bar = 100kPa
CALCULATION EXAMPLE OF 2-WAY VALVE FOR BY-PASS PRESSURE DROP
IN FUNCTION OF WATER FLOW RATE
Model 092 P2 D E8
Example at nominal conditions. Characteristics referred to entering air at 26°C-40%RH with chilled water temperature 7-12°C - 0% glycol
Water flow rate: 19,9 m
3
/h
Valve flow coefficient kv: 25 m
3
/h
2-way valve for by-pass pressure drop:
P = (Q / kv)
2
= (19,9/ 25)
2
= 0,633 (bar) * 100 (kPa / bar) = 63,3 kPa
