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Verfügbare Sprachen
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about the half of its full opening and leave the
pump running for a minute. Stop then the pump
for five minutes to allow the dissolution of air
bubbles which, if present, might endanger shaft
lubrication.
–
Start the pump and gradually open the delivery
gate valve till the water shows free of sand, or till
the suspended sand has dropped to a sufficiently
low percentage (40 g/m³).
–
Before definitively commissioning the pump,
remove starter fuses and check the electric circuit
integrity with an ohm-meter to make sure there
have been no damages when lowering the pump
in the well.
If the results are negative, lift the group again and
check it thoroughly.
–
For three-phases units, the electric resistance
value should be nearly the same for each phase.
–
Check insulation resistance to the ground (i.e.
between cable end and discharge pipe) using a
megahoms-meter. Minimum value to the ground
for a new pump is 10 megahoms with cold motor.
–
However, if some misfunctioning is detected
during startup, stop immediately the pump and
investigate the problem.
–
Check also that the pump runs within its operating
limits and that voltage rates reported on control
panel do not exceed motor nameplate rated
values.
–
If necessary, partially close gate valve or adjust
the intervention of pressure switches.
The system should be fully completed
before starting the pump, especially for
what concerns electrical, mechanical
and hydraulical components.
All safety systems must be correctly
operating.
The pump cannot run for more than 3
minutes with the gate valve closed to
avoid overheating of the unit.
7.2 Operation
The max. number of possible startups / hour depends
from motor power and starter type.
Up to 100 Hp = 10 startups / hour
100/200 Hp = 8 startups / hour
above 200 Hp = 5 startups / hour
If the pump does not start, avoid insisting without
having before investigated the reason.
All motors can afford ÷ 5% voltage deviation from
rated voltage values.
7.3 Running tests
In case of pump misfunctioning, perform the following
tests to find out the probable reasons:
FIRST TEST
–
Close fully the gate valve.
–
Note at startup the AMPS absorbed.
–
Note during operation.
–
Note pressure as reported by the pressure gauge
on delivery.
ENGLISH
–
Note vertical distance between water level and the
gauge dial center.
The following cases are possible:
Same pressure, same AMPS obsorbed:
–
If the gauge readings do not differ substantially
from previous readings, the impellers are not worn
and motor rotation is correct.
–
If the AMPS absorber did not change from the
original readings, the pump and motor internal
rubbing did not increase and the percentage of
water suspended sand is not representing a
problem for the pump.
Lower pressure:
–
Lower pressure means worn impellers, or too low
main voltage.
Higher AMPS absorbed:
–
This usually indicates a strong rubbing by the
bearing journals due to suspended solids.
SECOND TEST
–
Open completely the gate valve.
–
Note the AMPS absorbed.
–
Note pressure as reported by the pressure gauge.
–
Note pump delivery as reported by the flow meter.
The following case is possible:
–
Pump delivery lower than rated delivery. This can
depend from scaling, from a clogged upstream
valve or from leaks along the pipe line.
8. MAINTENANCE
–
Periodical maintenance is strictly related to the
percentage of water suspended sand.
–
No maintenance is necessary as long as the
pump keeps running efficiently, i.e. pump delivery
keeps above 50% of rated delivery or the AMPS
absorbed do not exceeds the 5% allowance.
–
In some cases it will be necessary to replace worn
parts such as impellers, sealing rings or bearings.
–
In case of an high sand percentage, we suggest a
first inspection after a 1000 running hours.
–
During long idle periods in the well, the pump /
motor groups should be shortly started every 2 or
3 months.
–
Making sure the group is still fully submersed.
9. REPAIRING THE PUMP
9.1 Disassembling the pump / motor group
Because of its construction features, the pump and
motor group easily disassembled and re-assembled
with normal metric size shop tools.
–
If the pump adopts a non return valve, consider the
additional weight of the water-filled column besides
the group weight and use therefore a suited hoist.
–
We suggest to employ specialized personnel for
assembling and disassembling.
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