Frequency converter use may reduce the
lifespan of the bearings and the shaft seal,
depending on the operating mode and
other circumstances.
Check the following:
• Power consumption
• Motor liquid level.
When the pump is new or after replacement of the
shaft seals, check the motor liquid level and its water
content after one week of operation. If the motor
liquid level has dropped, the shaft seal may be
defective.
Dispose of the motor liquid must comply
with local regulations.
Number of poles
Quantity of motor liquid
SE
[ltr]
SL
[ltr]
2 12.8 4.5
4 12.8 4.5
6 14.1 5.4
• Cable entries: Make sure that the cable entries
are waterproof and the cables are not sharply
bent or pinched.
• Impeller clearance: Check the impeller
clearance.
• Pump parts: Check the pump housing and other
parts for possible wear. Replace defective parts.
• Ball bearings: Check the shaft for noisy or heavy
operation (turn the shaft by hand). Replace
defective ball bearings.
• General maintenance: It is usually required in
case of defective ball bearings or poor motor
function. This work must be carried out by an
authorised service workshop.
Replace the ball bearings at least every
25.000 operating hours.
8.1 Motor liquid check and change
Clean the outside of the pump regularly to
retain the heat conductivity.
Change the motor liquid once a year or
after 2000 operating hours to prevent
oxidation.
Lack of motor liquid may cause
overheating and damage to the
mechanical seals.
Use SML3 cooling liquid for motor cooling.
Cooling liquids with lower specific heat
capacity than SML3 may cause
overheating to the motor.
8.1.1 Checking the motor liquid
The ingress level of the pumped liquid into the motor
liquid can be checked. Use a refractometer (product
no. 98676968) which shows the refractive index in
percent. Always use the propylene glycol scale.
Measured freezing point
Liquid ingress
percent (%)
-20 °C (-4 °F) 0
-18 °C (0.4 °F) 5
-17 °C (1.4 °F) 10
-15 °C (5 °F) 15
-14 °C (6.8 °F) 20
If the refractive index is higher than 20 %, change the
motor liquid.
Do not exceed this level of refractive index to ensure
the appropriate condition of the shaft seal and the
bearings for reliable operation. For further
information, see the service instruction for SE, SL
pumps.
QR98248406
For draining and changing the
motor liquid, see the SE/SL 9-30
kW Service instructions
http://net.grundfos.com/qr/i/
98248406
25
English (GB)
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