DESMI PUMPING TECHNOLOGY A/S
-10-
Tagholm 1
9400 Nørresundby - Denmark
Tel.: +45 96 32 81 11
Fax +45 98 17 54 99
E-mail:
10.
SYSTEM
BALANCING
It is often difficult to calculate a manometric delivery head in advance. It is, however, decisively
important to the quantity of liquid delivered.
A considerably smaller delivery head than expected will increase the quantity of liquid delivered,
causing increased power consumption and perhaps cavitation in pump and piping. In the pump the
impeller may show signs of heavy erosion caused by cavitation (corrosion) which may at times
render an impeller unfit for use in a very short time. Not unusually do similar erosions occur in pipe
bends and valves elsewhere in the piping system.
Therefore, after start-up, it is necessary to check either the quantity of liquid delivered or the power
consumption of the pump e.g. by measuring the current intensity of the connected motor. Together
with a reading of the differential pressure the quantity of water delivered can be determined against
the characteristics of the pump.
In cases where the liquid flow of the pump has to be reduced a valve in the piping system is the
most common solution. This valve
always
has to be placed on the suction side of the pump - never
on the delivery side.
Should the pump not function as intended, please proceed according to the fault-finding list. Bear in
mind, though, that the pump was carefully checked and tested at the factory and that the majority of
faults stem from the piping system.
