Startup; General Information; Priming; Checking The Direction Of Rotation - Grundfos NB Series Installation And Operating Instructions Manual

11. Startup

Do not start the pump until it has been
Caution
filled with liquid and vented.

11.1 General information

Warning
When pumping drinking water, flush the
pump with clean water before startup in
order to remove any foreign matters such
as preservatives, test liquid or grease.
11.1.1 Flushing the pipe system
The pump is not designed to pump liquids
containing solid particles such as pipe
debris and welding slag. Before starting up
the pump, the pipe system must be
thoroughly cleaned, flushed and filled with
Caution
clean water.
The warranty does not cover any damage
caused by flushing the pipe system by
means of the pump.

11.2 Priming

Closed systems or open systems where the
liquid level is above the pump inlet
1. Close the isolating valve in the outlet pipe and
slowly open the isolating valve in the inlet pipe.
Both the pump and the inlet pipe must be
completely filled with liquid.
2. Loosen 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
liquid does not cause personal injury or
damage to the motor or other components.
In hot-liquid installations, pay special
attention to the risk of personal injury
caused by scalding hot liquid.
In cold-liquid installations, pay special
attention to the risk of personal injury
caused by the cold liquid.
Suction operation with non-return valve
The inlet pipe and the pump must be filled with liquid
and vented before the pump is started.
1. Close the isolating valve in the outlet pipe and
slowly open the isolating valve in the inlet pipe.
2. Remove the priming plug, M.
3. Pour liquid through the hole until the inlet pipe
and the pump are completely filled with liquid.
4. Fit the priming plug, M.
The inlet pipe may be filled and vented via the
priming plug. See fig. 24. 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 inlet side of
the pump, the valve must be fully open.
2. Close the isolating valve in the outlet pipe and
tighten the priming and drain plugs.
3. Connect a manual venting pump instead of a
priming device with funnel.
4. Install a slide valve 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 inlet pipe using short,
rapid pump strokes until the liquid runs out on the
outlet side.
6. Close the valve at the venting pump.
E: Drain plug
M: Priming plug
Fig. 24 Drain and priming plug

11.3 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. 24.
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