Grundfos NK Serie Instrucciones De Instalación Y Funcionamiento página 28

11.2.2 Oil-lubricated bearings
Fig. 34 Bearing bracket with oil-lubricated roller and double
angular contact bearings
Under optimum operating conditions, the life of the roller and
double angular contact bearings will be approx. 100,000
operating hours. After that period, it is advisable to replace the
bearings. See section 13.1 Service
To monitor the bearing condition, regularly measure
vibration levels using the SPM measuring points on
Note
the bearing bracket. See section
level.
The bearings are lubricated with mineral oil. Intervals for oil
change as well as the required quantities are specified below.
Bearing
Initial oil change
temperature
Up to 70 °C
After 400 hours
70-90 °C
Diameter of
Bearing type coupling shaft
[mm]
42
Roller and angular
48
contact bearings
60
Changing of oil
Step Action
Place a suitable container under the bearing bracket to
1
collect used oil.
2 Remove the vent/filling plug and the drain plug.
After drainage of the bearing bracket, fit the drain plug,
3 and fill the bearing bracket with new oil. See section
7.8.2 Bearing bracket with constant-level
Check the oil level regularly during operation, and
add oil, if necessary. The level must always be visible
Note
in the sight glass.
Basic characteristics
Shell Omala 68
Viscosity grade
AGMA EP Gear Oil Grade
Old AGMA Grade
Viscosity:
At 40 °C, 104 °F
At 100 °C, 212 °F
Flash point, COC, °F
Pour point, °F
28
kits.
7.9.1 Vibration
Subsequent oil
changes
Every 4400 hours
Every 2200 hours
Approximate oil
quantity
[ml]
850
1700
1350
oiler.
Test method
ISO 68
68
2 EP
2
D 445 68 mm /s
2
D 445 8.8 mm /s
D 92 405
D 97 -15
11.3 Monitoring equipment
It is advisable to take weekly readings of these parameters:
• vibration level - use SPM measuring points
• bearing temperature - if sensors have been fitted
• inlet and outlet pressure - use pressure gauges.
Alternatively, follow the maintenance plan laid out for your
application.
11.4 Motor
Check the motor at regular intervals. It is important to keep the
motor clean in order to ensure adequate ventilation. If the pump
is installed in a dusty environment, it must be cleaned and
checked regularly.
11.4.1 Lubrication
Motors up to and including frame size 132 have maintenance-
free, greased-for-life bearings.
Motors of frame sizes larger than 132 must be greased according
to the indications on the motor nameplate. Grease spills from the
motor may occur.
Grease specifications: See section
11.4.2 Bearing grease
Lithium-based grease according to the following specifications
must be used:
• NLGI class 2 or 3
• viscosity of basic oil: 70-150 cSt at +40 °C
• temperature range: -30 - +140 °C during continuous operation.
12. Periods of inactivity and frost protection
Pumps which are not being used during periods of frost must be
drained to avoid damage.
Drain the pump by removing the drain plug. See fig. 28.
Do not tighten the priming plug or replace the drain plug until the
pump is to be used again.
Warning
Care must be taken to ensure that the escaping
liquid does not cause personal injury or damage to
the motor or other components.
In hot-liquid installations, pay special attention to the
risk of personal injury caused by scalding hot liquid.
In cold-liquid installations, pay special attention to
the risk of personal injury caused by cold liquid.
If the pump is to be drained prior to a long period of inactivity,
inject a few drops of silicone oil on the shaft at the bearing
bracket. This will prevent the shaft seal faces from seizing up.
11.4.2 Bearing grease.