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JV, JVI, JVN Vertical Multistage Centrifugal Pump ... - Javelin Pumps

JV, JVI, JVN Vertical Multistage Centrifugal Pump ... - Javelin Pumps

JV, JVI, JVN Vertical Multistage Centrifugal Pump ... - Javelin Pumps

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Minimum inlet pressure NPSH<br />

If the pressure in pump is lower than the vapour<br />

pressure used to convey liquid, cavitation will occur. To<br />

avoid cavitation, a minimum pressure at the inlet side of<br />

the pump shall be guaranteed. The maximum suction lift<br />

can be calculated with following formula:<br />

H = Pb x 10.2 - NPSH - Hf - Hv - Hs<br />

Pb = atmosphere pressure [bar] (can be set as 1 bar)<br />

In a closed system, Pb means system pressure [bar]<br />

NPSH= Net positive suction head [m], It can be read out<br />

from the point of possible max. flow rate shown on<br />

NPSH curve<br />

Hf = Pipeline loss at the inlet [m]<br />

Hv = Steam pressure [m]<br />

Hs = Safety margin Minimum 0.5m delivery head<br />

If the calculated result H is positive, the pump may run<br />

under the max. suction lift H. In case the calculated<br />

result H is negative, a delivery head of min. inlet pressure is<br />

necessary.<br />

Operation Operation in in parallel parallel<br />

- Connecting several pumps in a parallel running mode will<br />

benefit the reliability of the system compared to a single<br />

pump system.<br />

- Applicable to different working states required by a variable<br />

flow system.<br />

- Increasing the availability of water supply if a pump fails:<br />

only a part of the system flow is affected.<br />

G E N E r A l D A t A<br />

Check and ensure that the pump is not at cavitation<br />

state.<br />

Two pumps or more can be connected in parallel<br />

running if necessary.<br />

10 J AV E L I N - V E R T I C A L M U LT I S TA G E C E N T R I F U G A L P U M P S

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