Grundfos NK Montage- Und Betriebsanleitung Seite 32

10. Maintenance
Warning
Before starting work on the pump, switch off the
supply voltage. It must be ensured that it cannot
be accidentally switched on.
10.1 Pump
The pump is maintenance-free.
If the pump is to be drained for 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 sticking.
10.1.1 Mechanical shaft seals
Mechanical shaft seals are maintenance-free, working almost
without any leakages. If any considerable and increasing
seepage occurs, the mechanical shaft seal should be checked
immediately. If the sliding surfaces are damaged, the entire shaft
seal should be replaced. Mechanical shaft seals should be
treated with the greatest care.
10.1.2 Stuffing box
The stuffing box gland must not be too tight during start-up in
order to let sufficient liquid lubricate the shaft and the packing.
Once the stuffing box housing and the stuffing box gland have
reached approximately the same temperature as that of the pump
parts, the running-in of the stuffing box gland has been
completed. If the stuffing box leaks too much, retighten slightly
and evenly while the pump is running. To ensure continuous
lubrication, a few drops should always drop from the stuffing box
to protect the packing or shaft sleeve against damage.
20 to 40 drops/minute are recommended.
If the stuffing box leaks too much and it cannot be further
tightened, the stuffing box must be repacked. After removal, clean
and check the shaft sleeve, chamber and stuffing box gland.
For further information, see the service instructions for NK.
10.2 Lubrication of bearings in bearing bracket
10.2.1 Grease-lubricated bearings
Pump with greased-for-life bearings
Fig. 27 Bearing bracket with closed, greased-for-life bearings
If the bearing bracket has no grease lubricators or constant-level
oiler, the bearings are greased-for-life deep-groove ball bearings.
The ball bearings are maintenance-free.
Under optimum operating conditions, the bearing life will be
approx. 17,500 operating hours. After that period, it is advisable
to replace the bearings. See section 12.1 Service kits.
To check the bearings, regularly listen to them by
Note
means of a solid rod. For this bearing bracket
type, there are no SPM measuring points.
32
Pump with automatic grease lubricators
Fig. 28 Bearing bracket with open roller and double angular
contact bearings lubricated by automatic grease
lubricators (grease cartridges)
If the pump has automatic grease lubricators, the grease in the
bearings will continuously be renewed.
Under optimum operating conditions, the bearing life will be
approx. 100,000 operating hours. After that period, it is advisable
to replace the bearings. See section 12.1 Service kits.
New bearings must be filled with grease according to Grundfos
specifications.
To monitor the bearing condition, regularly
measure vibration levels using the SPM
Note
measuring points on the bearing bracket. See
section 6.8.1 Vibration level.
Automatic grease lubricators
Replace lubricators every 12 months. When replacing the
lubricators, open the drain hole in the bottom of the bearing
bracket for one hour during operation to remove old and excess
grease.
Grundfos recommends SKF SYSTEM 24 lubricators,
type LAGD 125/HP2.
Basic characteristics
Code, DIN 51825
Consistency class, NLGI
Thickener
Base oil
Operating temperature
Dropping point, ISO 2176
Density, DIN 5175
Base oil viscosity
40 °C (104 °F)
100 °C (212 °F)
Quantity
2 x LAGD 125/HP2
Never mix greases with different thickeners, such
as a lithium-based grease with a sodium-based
grease, before checking with the suppliers.
Never mix a mineral oil with a synthetic oil.
Caution
Some lubricants are compatible, but assessing
the compatibility of two lubricants can be
difficult. As a general rule, always relubricate a
bearing with the same lubricant used originally.
K2N-40
2-3
Polyurea (di-urea)
Mineral
–40 to 150 °C (–40 to 302 °F)
240 °C (464 °F)
at 20 °C (68 °F):
3
0.85 - 0.95 g/cm
2
96 mm /s
2
10.5 mm /s
Product number
96887371