Pump Overhaul; Motor Liquid Check And Change - Grundfos SL Instructions Manual

• Ball bearings: Check the shaft for noisy or heavy operation; turn the shaft manually. Replace defective
bearings. A general overhaul of the pump is usually required in case of defective bearings or poor motor
function. This work must be carried out by an authorised service workshop. Bearings are lubricated for
lifetime.
• Vibration: If the pump is vibrating at an abnormal level, do not restart the pump until the cause of the fault is
identified and eliminated.
• 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.

9.1 Pump overhaul

Pumps running in normal operation require major overhaul after 24.000 operating hours or 6 years, whichever
comes first. The overhaul includes the replacement of the following:
• shaft seal
• bearings
• wear parts
• gaskets
• O-rings
• motor liquid.

9.2 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 3.000 operating hours to prevent oxidation.
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 percentage. Always use the propylene glycol scale.
Measured freezing point
-20 °C (-4 °F)
-18 °C (0.4 °F)
-17 °C (1.4 °F)
-15 °C (5 °F)
-14 °C (6.8 °F)
If the refractive index is higher than 20 %, change the motor liquid.
Pump type
SL
Do not exceed this level of refractive index to ensure the appropriate condition of the shaft seal and the bearings
for reliable operation.
Drain the leakage chamber of the pump after 12.000 operating hours.
26
Liquid amount (l)
13
Liquid ingress (%)
0
5
10
15
20