They were experiencing poor balance device life due to the disc/counter disc design (no thrust bearing) and locating the balancing disc using a shaft screw.  The operating life of the pumps between major overhauls on occasion did not reach 10,000 hours.

With the help of Sulzer Pumps retrofit know-how the inner pump cartridge was replaced, providing improved mechanical properties and a significant increase of pump efficiency of over 10 %.

The operational lifetime between overhauls was extended to more than 50,000 hours, even after 40,000 hours operation no decrease in efficiency was apparent.