Pipework; Suction Pipe - Grundfos CHV 2-40 Montage- Und Betriebsanleitung

2.3 Pipework

The pipes should be fitted so that any tension
caused by variations in temperature does not affect
the pump.
The pipe hanger should be positioned as close as
possible to the pump, see pos. 3 in fig. 3.
To minimize possible noise from the pump, it is
advisable to fit expansion joints either side of the
pump and anti-vibration mountings between
foundation and pump, see pos. 1 in fig. 3.
Isolating valves should be fitted either side of the
pump to avoid draining the system if the pump needs
to be cleaned, repaired or replaced, see pos. 2 in
fig. 3.
Install the pipes so that air locks are avoided,
especially on the suction side of the pump. Correct
pipework shown in fig. 3.
Fig. 3
Pos. Description Function
Reduces noise and
Expansion
1 absorbs vibrations and
joint
expansion.
Isolating Enables easy service of the
2
valve pump.
Supports pipe and absorbs
3 Pipe hanger
distortion and strain.
8

2.3.1 Suction pipe

If the pump is to draw liquid from a level lower than
the pump suction port, a foot/non-return valve must
be fitted to the end of the suction pipe, below the
lowest liquid level, since the pump is not self-
priming.
The suction pipe is connected to the pump suction
port S, fig. 4.
When the suction pipe is longer than 10 metres or
the suction lift is greater than 4 metres, the diameter
1 2 3
of the suction pipe must be larger than that of the
3
1 2
pump suction port.
Every joint of the suction pipe must be completely
tight.
If a hose is used as suction pipe, it must be non-
collapsible. A strainer is recommended in cases
where solids could enter the suction pipe and block
the pump.
2.3.2 Discharge pipe
The discharge pipe is connected to the discharge
port T, fig. 4.
The discharge pipe should be at least the same
diameter as the discharge port of the pump, to
minimize pressure drop, high flow velocities and
noise.
2.3.3 Bypass
If there is any danger of the pump running against
a closed discharge valve, a minimum liquid flow
through the pump should be ensured by connecting
a bypass/a drain to the discharge pipe. The drain
can for instance be connected to a tank.
A minimum flow rate equal to 10% of the flow rate at
maximum efficiency is needed at all times. Flow rate
and head at maximum efficiency are stated on the
pump nameplate.
S
Fig. 4
T