Minimum Suction Pressure; Maximum Pressures - HYDROO VDROO Serie Manual De Instrucciones De Instalación Y Operación

4.2. Minimum suction pressure

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Figure 4:
Drawing of an open
system with a VDROO
pump
Figure 5:
Pressure according to
temperature
The maximum suction "H" (Figure 4) can be worked out as follows:
H = P · 10,2 - NPSH - H
b
Where:
P = Atmosphere pressure in bars (atmosphere pressure can be adjusted to
b
1 bar in open systems, while in closed systems Pb indicates the system
pressure in bars).
NPSH = Positive net suction in meters column of water
(Check this value at APPENDIX A).
H = Friction losses in the suction pipe in meters column of water with regards
f
to the highest flow that the pump is providing.
H = Pressure in meters column of water.
v
Figure 5 provides pressure values according to the liquid temperature.
H = Safety margin = minimum 0.5 mcwa.
s
If "H" value is positive, the pump can operate at a maximum suction of "H" meters.
If "H" value is negative, a minimum supply pressure of "H" meters column of water
must be guaranteed. The pressure while in operation depends on the value calculated
for "H".

4.3. Maximum pressures

Maximum supply pressure and maximum operating pressure can be seen below.
However, the actual supply pressure plus the maximum pump pressure (without flow)
must always be below the values in Maximum operating pressure.
Pumps have been tested at 1.5 the maximum suction pressure.
- H - H
f v s
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