Commissioning And Startup; General Information; Commissioning; Priming - Grundfos NBG Series Installation And Operating Instructions Manual

11. Commissioning and startup

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

11.1 General information

Warning
When pumping drinking water, the pump
should be flushed through with clean water
before startup in order to remove any
foreign matters such as preservatives, test
liquid or grease.

11.2 Commissioning

11.2.1 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.

11.3 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 (M) 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-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 suction pipe and the pump must be filled with
liquid and vented before the pump is started.
1. Close the discharge isolating valve and slowly
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. 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 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. 24 Drain and priming plug

11.4 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.
25