Grundfos MQ Notice D'installation Et De Fonctionnement page 9

Carefully screw the discharge connection into
the discharge port, using a spanner or similar
tool. Hold the discharge connection, and
tighten the pump discharge union nut with your
hand. See fig. 5.
Fig. 5 Correct: Tighten the discharge
union nut with your hand
Fig. 6 Wrong: Do not use a tool to tighten
the discharge union nut
7.4.1 Suction pipes connected to a well
If the pump draws water from a well, we rec-
ommend to fit a foot valve to the end of the
suction pipe. See fig. 7.
Foot valve
Fig. 7 Suction pipes connected to a well
7.4.2 Suction hose instead of pipe
If a suction hose is used instead of a pipe, the
hose should not exceed the lengths stated in
the graph, page 62. The suction hose must be
minimum Ø1". The hose must be of the non-
collapsible type.
7.4.3 Long suction pipes
A separate non-return inlet valve is supplied
with the pump. In case of long suction pipes,
we recommend to fit the non-return inlet valve
in the pump suction port. See section
7.4.4 Fitting of the non-return inlet valve
The pipes must be adequately supported on
either side of the pump to avoid straining the
pump connections.
7.4.4 Fitting of the non-return inlet valve
The non-return inlet valve reduces the risk of
losing pump priming in negative suction appli-
cations and improves the auto-aspiration
capability, for example in water supply from a
cistern.
Install the non-return inlet valve as follows,
see fig. 8:
1. Remove the suction connection of the
pump.
2. Fit the non-return inlet valve into the suc-
tion port in the direction shown in fig. 8.
3. Refit the pump connection.
Applications with positive inlet
pressure do not require installa-
tion of the non-return inlet valve,
Note
due to the fact that the MQ pump
incorporates an internal non-
return valve at the discharge side.
Fig. 8 Fitting of non-return inlet valve
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