SRS- just another point of interest that adds to our confusion. We have two separate sulfur pits with the same length and style of pump, but different discharge pipe size and different numbers of intermediate bearings. We have one set of pumps that were originally designed for 1800rpm operation that we installed 3600rpm motors on to increase the discharge head with a 2X3″ jacketed discharge line. We have another set of pumps the exact same length, but with 3X4″ jacketed piping, designed for 3600rpm with 3600rpm motors on them. The key difference between them is the number of intermediate bearings on the pump shaft. The original 1800rpm pumps have one less intermediate bearing than the 3600rpm pumps. We are having a lot of problems with the pumps designed for 3600rpm and virtually no problems with the ones converted from 1800 to 3600. We believe the problems are related to the lubrication of the pump, but haven’t figured out how to completely resolve the problem yet.