J & S-Stork Pumps: Sealed Motor Pump Units and Turbine Alternator Units

Abstract

During the 1950s increasing temperatures and pressures in steam-generating plant exposed operating difficulties caused by gland-leakages in circulating pumps. An early solution to this problem was to enclose the pump and electric motor in a single pressure-tight shell, eliminating the need for glands or rotating seals. The shell was filled with water which lubricated and cooled the motor. This design had a fairly low limitation on operating temperature in order to protect the motor windings. The advent of the nuclear power industry in the USA provided a major stimulus to the development of leakproof pumps, because the containment of fission products during possible accidents was so important. Westinghouse developed a ‘canned’ motor-type pump and other firms followed suit. A problem in some applications was the limited temperature range caused by the difficulty of maintaining intact the insulation of the motor windings. There was also a restriction on the pumping of corrosive fluids which could attach the electrical connection and fittings.