Desmi ESLH/-17, Operation And Maintenance Instructions, Page: 13 / 19

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DESMI Pumping Technology A/S
13
www.desmi.com
Tagholm 1
9400 Nørresundby
– Denmark
Tel: +45 96 32 81 11 Fax: +45 98 17 54 99
E-mail:
desmi@desmi.com
In order to protect the shaft seal the pump must never run dry.
When the pump has been filled with cold and clean water(room temperature), the system
can be started. Check the direction of rotation. If the direction is incorrect interchange of the
power cords. The direction of rotation is indicated by an arrow. Make sure the bearings are
running correctly and that they do not become warm.
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.
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
FAULT CAUSE REMEDY
The pump has no
or too low capacity
1. Wrong direction of rotation
2. Piping system choked
3. The pump is choked
4. Suction line leaks
Pump takes air
5. Suction lift too high
6. Pump and piping system
wrongly dimensioned
Change direction of rotation to
clockwise when viewed from
shaft end (the direction of the
arrow)
Clean or replace
Clean the pump
Find the leakage, repair the fault,
non-return valve not submerged
Check data sheet Q/H curve and
NPSH or contact DESMI
As
The pump uses too
much power
1. Counter-pressure too low
2. The liquid is heavier
than water
3. Foreign body in pump
4. Electric motor is
running on 2 phases
Insert orifice plate or check
valve/Contact DESMI
Contact DESMI
Dismantle the pump, remove the
cause
Check fuses, cable connection,
and cable
The pump makes
noise
1. Cavitation in pump
Suction lift too high/ Suction line
wrongly dimensioned/Liquid
temperature too high