Planning The Installation - Wilo -NL 32-125 Einbau- Und Betriebsanleitung

4.4 Example of long code
NL 32-200-B 0.75-4-05-XX B
Norm pump code
Ø Discharge port
Ø max. impeller
Hydraulic version
Motor power (kW)
2 or 4 poles
05 - Std mechanical version (without spacer)
12 - Std mechanical version (with spacer)
Technical definition code
Indice of technical evolution
4.5 Shaft seal
Depending on the application, different shaft
sealing executions are offered (see 4.3).
NOTE : Chapter 4.3 contains the codes for all
variations of mechanical seals.
A stuffing box with lantern ring or mechanical
seals according to DIN 24960 are fitted in the
following cases:
If the pump draws from a suction line, If the
pump is fed by a feed line with a pressure of less
than 0.5 bar or If the pumped liquid is at or near
its boiling point.

5. Planning the installation

5.1 Piping system
- Note the arrows on the pump branches indicating
the direction of flow.
- Choose the nominal width of the pipelines in
accordance with the nominal width of the pump
branches or larger ones with the corresponding
reductions.
- Flange sealing must not protrude on the inside.
- Ensure that the pipe work is clean before installing
of the pump.
- Support the pipe work in order to avoid distortions
at the pump components (risk of damage to pump
components).
- Avoid abrupt changes of cross section and direc-
tion.
- Where different diameter pipe work is to be used,
connection should be by eccentric transition
pieces. This will avoid the formation of air pockets
in the pipe work (fig. 2).
- For difficult pumping on the suction side, to stabi-
lise the flow, a pipe length 15 times the diameter of
the suction branch should be installed before the
suction branch (fig. 2).
- The flow rate in the suction line or inflow line must
not exceed 2 - 3 m/s.
5.1.1 Suction line
See the sketches below for the optimum layout
of pump installation for flow and suction lift
operation.
WILO AG 09/2007
Pump under pressure
Fig. 1
Ensure that air pockets cannot be created.
Unequal nominal widths of the suction branch
and suction line must be compensated by eccen-
tric transition pieces (fig. 2).
Fig. 2
• It is recommended that a strainer is installed in
front of the pump with a filter surface of at least
3 times the pipe cross section (approx. 100
meshes/cm2).
• The suction opening of the suction line should be
well below the liquid level, and a strainer should
be used.
The strainer must be far enough from the bot-
tom to avoid excessive inlet losses, which could
impair pumping performance. It is advisable to
check that there is no leakage.
A shut-off valve should be installed in the feed
line. It must be closed for maintenance work. It
should be installed in order to avoid air pockets
forming in the spindle cap, i.e. with the spindle in
a horizontal position or pointing vertically down-
ward.
1 Eccentric reducer (suction) or
concentric reducer (discharge)
2 Isolating valve
3 Suction line
4 Bend
5 Foot valve with strainer
6 Isolating valve
7 Regulating valve
Fig. 3
English
Pump in suction
25