Suction Line; Discharge Line; Mechanical Seal - Wilo SCP Série Notice De Montage Et De Mise En Service

English

7.2.5 Suction line

See the sketches figure 7 for the optimum layout
of pump installation for flow and suction lift ope-
ration. Ensure that air pockets cannot be created.
Unequal nominal widths of the suction branch and
suction line must be compensated by eccentric
transition pieces (refer figure 8).
• It is recommended that a strainer is installed in
front of the suction pipe 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 bottom
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.
Layout of pump installation
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
58

7.2.6 Discharge line

CAUTION! Damage to the pump
Pump casings have sometimes been cracked by
pressure surges imposed on them through the
absence of a non-return valve. A back flow can
serisouly damage the bearings and the mechani-
cal seal.
For flow regulation, a valve must be installed
behind the pump. If non-return valves are used,
they should close smoothly. Pressure shocks must
be avoided.
7.2.7 Stuffing box packing (fig. 9)
CAUTION! Risk of quick wear or leakages
Packing should be handled with care and it
should not be allowed to pick up the dust or
abrasive matter by coming into contact with
floors or dirty benches. It is bad practice to ham-
mer packing to facilitate the insertion.
Pumps are dispatched from our works with the
stuffing boxes unpacked; otherwise packing will
be aged. The packing is packed with greaseproof
paper and dispatched with the pump. The softest
possible packing i.e. plaited cotton impregnated
with oil and colloidal graphite is recommended for
most duties. Required number of and lengths of
packing should be cut off so that each length will
pass once round the shaft sleeve line and meet to
end. The ends of packing must be cut at 45 °. After
cleaning the stuffing box and shaft sleeves the
packing should be inserted into the stuffing box.
Each ring should be pushed into position individu-
ally using the glands joint of each ring must be
positioned 180˚ from joints of its neighbour. A
logging ring included in the arrangement; should
be inserted into the stuffing box at the appropri-
ate time during the packing sequence so that it is
aligned with the cooling water connection. The
gland should now be fitted square with the pump
casing and the nut should be screwed up to little
more than finger tightness.

7.2.8 Mechanical seal

CAUTION! Damage to the pump
Never start the pump without liquid inside
otherwise the mechanical seal will be damaged
instantaneously.
No real operation is required during the setup of
the pump. Only filling and venting the pump are
mandatory before switching on the main.
7.2.9 Pressure gauge connections
CAUTION! Risk of leakage of the fluid!
Never connect a pressure gauge onto the pump
when the system is under pressure.
Pressure gauge connections are available on the
pump casing close to the flanges. Then pressure
gauge can be connected on suction and discharge
side.
WILO SE 10/2019