Pipework - Grundfos CM Serie Instrucciones De Instalación Y Funcionamiento

6.2 Pipework

We recommend that you fit isolating valves on either
side of the pump. It is thus not necessary to drain the
system if the pump needs service.
If the pump is installed above the liquid level, a
non-return valve must be fitted in the suction pipe
below the liquid level. See fig. 4.
Self-priming pumps:
We recommend an opening pressure of
the non-return valve which is lower than
Note
0.05 bar. Otherwise the additional
resistance will reduce the suction
capability of the pump.
If the pump is to be used for pumping rainwater or
well water, we recommend that you fit a filter to the
inlet of the suction pipe.
The pump must not be stressed by the pipework.
Install the pipes according to the design
requirements given in EN ISO 13480-3:2012.
Tolerances must comply with EN ISO 13920:1996,
class C.
The pipework must be correctly sized taking due
account of the pump inlet pressure.
Install the pipes so that air locks are avoided,
especially on the suction side of the pump. See fig.
2.
Fig. 2 Pipework
8
6.2.1 Pipe connection (non-self-priming pumps)
Take care not to damage the pump when
connecting the suction and discharge
pipes.
Caution
Torque: 50-60 Nm. The stated torque must
not be exceeded.
Discharge port
Fig. 3 Suction and discharge ports
6.2.2 Pipe connection (self-priming pumps)
The pump must be installed correctly to ensure that it
can self-prime.
Take the following precautions:
See fig. 4.
• The minimum height from the centre of the
suction port to the first tapping point (H
observed.
If a pressure manager is installed in the system,
H is the height from the centre of the pump
1
suction port to the pressure manager.
Minimum heights appear from the table below.
• The suction pipe must be at least 0.5 metres
below the liquid level (H
For optimum suction capability, the pump
must be located near the well or tank to
ensure that the suction pipe is as short as
Note
possible. This will reduce the self-priming
time, especially in the case of a high
suction lift.
We recommend that you install a filling plug in the
discharge pipe. This facilitates liquid filling before
startup. See fig. 4, pos. A.
Suction port
) must be
1
).
3