In this specific case, we were approached by Grundfos Almere to consider in time improvements due to our seal expertise.
On a sewage treatment plant 12 shaft pumps type S3200 are installed.
These pumps cavitated because they are pumping on process needs instead of operating the pump near the BEP.
The result is that the top seal in the oil chamber fails and the engine is full of water and oil. The bottom seal also fails.
Lifetime is in some cases less than 2 months. All signal cables are connected and rotated until the pump really stops by full closing in the engine!
The Sellon solution
After inspection of a number of pumps and the relevant seals, we concluded that storage fluid could flow into the seal through the pump shaft, after which it cooled down on the seal. Seal fails.
We also found that a CB stationary face was placed in the upper seal. Oil and CB is not an ideal solution!
We have indicated 3 modifications:
1) CB Level replaced with an SSC level in combination with a Chesterton 491 Seal 100mm.
2) We machined the bearing chamber cover and fitted it with a 14K turn ring to keep the grease away from the seal.
3) We have supplied a splash ring which is clamped around the outer sleeve of the seal so that the surfaces always provide sufficient lubrication. Even if the level in the oil chamber dropped slightly.