Motor pump family with single stage and multiple stage impellers

摘要

A motor pump group has a plurality of centrifugal pumps of the same nominal port diameter including a plurality of impellers having stepwise greater outside diameters for stepwise higher pump heads, and a plurality of respective motors for actuating the pumps. The pump heads are classified into a low head section and a high head section. The low head section is handled by a single-stage impeller, and the high head section is handled by multi-stage impellers. The centrifugal pumps have respective pressed-sheet pump casings. The outside diameters of the impellers are not required to be increased in the high head section, and the outside diameters of the pump casings fall in a relatively small range.