TROUBLESHOOTING
DESMI Pumping Technology A/S
Tagholm 1
9400 Nørresundby
– Denmark
Tlf. nr.: +45 96 32 81 11
Fax +45 98 17 54 99
E-mail: [email protected]m
60
7.
TROUBLESHOOTING
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. Similar erosions also 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.
If the pump does 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
Change direction of rotation to
clockwise when viewed from shaft
end (the direction of the arrow)
2. Piping system is choked
Clean or replace the piping
system
3. The pump is choked
Clean the pump
4. Suction line leaks
Find the leakage, repair the fault,
non-return valve not submerged
5. Pump takes air
6. Suction lift is too high
Check data sheet Q/H curve and
NPSH or contact DESMI
7. Pump and piping system
wrongly dimensioned
As 5
The pump uses too
much power
1. Counter-pressure is too low Insert orifice plate or check valve
/ Contact DESMI
2. The liquid is heavier than
water
Contact DESMI
3. Foreign body in pump
Dismantle the pump, remove the
cause
4. Electric motor is running on
2 phases
Check fuses, cable connections,
Содержание NSL 100-215
Страница 2: ......
