Wilo NPG Series Installation And Operating Instructions Manual page 14

When adjusting an operating stuffing box (shield
grids removed for this operation) the operator
must be very careful. Safety gloves are compul-
sory and loose clothes are not allowed (above all
to the arms) to avoid being caught by the pump
shaft.
The pump should be run for ten minutes with
steady leakage and the gland nuts tightened by
10 degrees at a time until leakage is reduced to an
acceptable level.
The temperature of the gland should be checked
after each round of tightening. If the temperature
starts to climb rapidly then back off the gland nuts
until the temperature drops down. Wait for the
temperature to stabilize before tightening again.
The leakage must not be reduced below a rate of
20 drops per minute.
Bedding in of the packing may take several hours
Shield grids being removed during installation of
the gland packing, it must be ensured that they
are replaced as soon as this operation is comple-
ted.
5.5.3 Pump fitted with mechanical seal
A mechanical seal ensures a seal without leakage
and does not need any adjustment. Nevertheless
if a light leakage occurs during start-up, it should
disappear after the initial running in of the friction
faces.
Mechanical Seal
For NPG 150-200,
200-250, 200-315
200-355, 250-250
250-315, 300-300,
65-315A, 100-315A
Installation and maintenance instructions Wilo-Horizontal pumps
.
Never run a mechanical seal dry, even for
CAUTION!
a short while.
Safety instructions when the pump is running.
If hot or freezing components of the machine can
present a danger to operators, they must be shiel-
ded to avoid accidental contact. If a 100 % pro-
tection is not possible, the machine access must
be confined to the maintenance staff only.
If the temperature is greater than 80 °C, a war-
ning plate must be clearly placed on the pump.
It is strictly forbidden to open switch cupboards,
switch boxes, or all other live electric equipment.
If it is necessary to open them in order to take rea-
dings, to carry out tests or adjustments for
example, only a skilled technician may do them
with adapted tools. Make sure that physical pro-
tections against electrical risks are used.
5.5.4 Bearings
It is important, particularly with grease lubrication,
to keep a check on bearing temperatures. After
start up the temperature rise should be gradual,
reaching a maximum after approximately 1.5 to
2 hours. This temperature rise should then remain
constant or marginally reduce with time.
5.5.5 Normal vibration levels, alarm and trip
For guidance, pumps generally fall under a classi-
fication for rigid support machines within the
International rotating machinery standards and
the recommended maximum levels below are
based on those standards.
Vibration velocity - unfiltered
Normal
Alarm
Shutdown trip
NPG
Simple mechanical seal
Other NPG
Balanced mechanical seal
Other NPG
mm/s (in./s)r.m.s.
N 5.6 (0.22)
N x 1.25 7.1 (0.28)
N x 2.0 11.2 (0.44)
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