Flowserve NM - Manual (Page 21)

NM USER INSTRUCTIONS ENGLISH 71576289 - 11/09
Page 21 of 48
Shield grids being removed during installation
of the gland packing, it must be ensured that they
are replaced as soon as this operation is completed.
If hot liquids are pumped (105 °C < t
≤
140 °C), the
stuffing box includes a thermal barrier to avoid
evaporation in the packing zone, which would
quickly destroy the gland packing.
As leakages are reduced and the cooling is made
more efficient (flow and temperature of cooling
water), it is observed that the packing gland will last
longer.
5.6.3 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.
9 2 1 0
4 6 1 0
9 2 2 0
4 2 1 3
Simple mechanical seal
9 2 1 0
9 2 2 0
4 2 1 3
4 6 1 0
Balanced mechanical seal
NEVER RUN A MECHANICAL SEAL
DRY, EVEN FOR 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
shielded to avoid accidental contact. If a 100 %
protection is not possible, the machine access must
be confined to the maintenance staff only.
If the temperature is greater than 80 °C, a
warning plate must be clearly placed on the pump.
The adjusting lines, the stuffing box, the lines
under pressure or the mechanical seal cooling lines
must be protected against external knocks.
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 readings, to carry out tests or adjustments for
example, only a skilled technician may do them with
adapted tools. Make sure that physical protections
against electrical risks are used.
5.6.4 Bearings
If the pumps are working in a potentially
explosive atmosphere, temperature or vibration
monitoring at the bearings is recommended. If
bearing temperatures are to be monitored it is
essential that a benchmark temperature is recorded
at the commissioning stage and after the bearing
temperature has stabilized.
•
Record the bearing temperature (t) and the
ambient temperature (ta)
•
Estimate the likely maximum ambient
temperature (tb)
•
Set the alarm at (t+tb-ta+5)
°
C [(t+tb-ta+10)
°
F]
and the trip at 100
°
C (212
°
F) for oil lubrication
and 105
°
C (220
°
F) for grease lubrication
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.
5.6.5 Normal vibration levels, alarm and trip
For guidance, pumps generally fall under a
classification for rigid support machines within the
International rotating machinery standards and the
recommended maximum levels below are based on
those standards.