ABSTRACT
A major deficiency of centrifugal pumps is that the pump chamber must be filled completely with water upon startup for it to function correctly. In potable water service, submersibles provide high pressure for deep well pumping when equipped with multi-stage impellers. Submersible pumps are vertical, close-coupled, heavy duty centrifugal pumps designed to work submerged in the water which they are pumping. The affinity laws show theoretical expected performance, but the curve shows exactly how the pump will operate. Advantages of using variable speed pumps are in the energy savings obtained by operating close to peak efficiency regardless of changing system needs, and in the ability of the pump to discharge less water when demand is for less, with resultant smaller horsepower demand. The effects of cavitation are most damaging in areas where it is occurring repeatedly. Cavitation will occur, with resulting chipping and destruction of internal pump parts.
