Grundfos NK Montage- Und Betriebsanleitung Seite 31

9. Start-up
Do not start the pump until it has been filled with
Note
liquid and vented.
9.1 General
In the case of pumps with stuffing box, check that the stuffing box
gland is correctly fitted. It should be possible to turn the pump
shaft manually. When inactive for a long period, the pump should
first be loosened by turning it manually, if it has got stuck.
Loosen the stuffing box or remove the packing.
Warning
When pumping drinking water, the pump should
be flushed through with clean water before start-
up in order to remove any foreign matters such as
preservatives, test liquid or grease.
9.2 Priming
Closed systems or open systems where the liquid level is
above the pump inlet
1. Close the discharge isolating valve and slowly open the
isolating valve in the suction pipe. Both the pump and the
suction pipe should be completely filled with liquid.
2. Slacken the priming plug in order to vent the pump.
Once liquid runs out, tighten the priming plug.
Warning
Pay attention to the orientation of the priming
hole to ensure that the escaping water does not
cause personal injury or damage to the motor or
other components.
In hot-water installations, special attention
should be paid to the risk of personal injury
caused by scalding hot water.
Suction operation with non-return valve
The suction pipe and the pump must be filled with liquid and
vented before the pump is started.
1. Close the discharge isolating valve and open the isolating
valve in the suction pipe.
2. Remove the priming plug (M).
3. Pour liquid through the hole until the suction pipe and the
pump are completely filled with liquid.
4. Fit the priming plug (M).
The suction pipe may be filled and vented via the priming plug.
See fig. 26. Alternatively a priming device with funnel can be
installed before the pump.
Open systems where the liquid level is below the pump inlet
1. If an isolating valve is fitted on the suction side of the pump,
the valve must be fully open.
2. Close the discharge isolating valve and tighten the priming
and drain plugs.
3. Connect a manual venting pump instead of a priming device
(funnel).
4. A slide valve should be installed between the venting pump
and the centrifugal pump in order to protect the venting pump
against excessive pressure.
5. Once the slide valve at the manual venting pump has been
opened, vent the suction pipe using short, rapid pump strokes
until the liquid runs out on the discharge side.
6. Close the valve at the venting pump.
E Drain plug
M Priming plug
Fig. 26 Drain and priming plug
9.3 Checking the direction of rotation
Warning
The pump must be filled with liquid when
checking the direction of rotation.
The correct direction of rotation is shown by arrows on the pump
housing. Seen from the pump end, the direction of rotation must
be counter-clockwise. See fig. 26.
9.4 Start-up
Before starting the pump, completely open the isolating valve on
the suction side of the pump and leave the isolating valve on the
discharge side almost closed.
Start the pump.
Vent the pump during starting by loosening the air vent screw in
the pump head/cover until a steady stream of liquid runs out of
the vent hole.
Warning
Pay attention to the orientation of the vent hole to
ensure that the escaping water does not cause
personal injury or damage to the motor or other
components.
In hot-water installations, special attention
should be paid to the risk of personal injury
caused by scalding hot water.
When the pipework has been filled with liquid, slowly open the
isolating valve on the discharge side until it is completely open.
Warning
If the motor is fitted with a motor with an output
selected on the basis of a specific maximum flow
rate, the motor may be overloaded if the
differential pressure is lower than anticipated.
Check the overload by measuring the motor current consumption
and comparing the value with the nominal current stated on the
motor nameplate. In case of overload, throttle the valve on the
discharge side until the motor is no longer overloaded.
It is advisable always to measure the motor current consumption
during starting.
At the moment of start, the input current of the
Note
pump motor is up to six times higher than the
full-load current stated on the motor nameplate.
9.5 Start/stop
Maximum number of starts/hour
Frame size
2
56 - 71 100
80 - 100 60
112 - 132 30
160 - 180 15
200 - 225 8
250 - 315 4
9.6 Reference readings of monitoring equipment
It is advisable to take initial readings of these parameters:
• vibration level (use SPM measuring points)
• bearing temperature (if sensors have been fitted)
• inlet and outlet pressure (use pressure gauges).
They can be used as reference in case of abnormal operation.
Number of poles
4 6
250 350
140 160
60 80
30 50
15 30
8 12
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