JPS5791395A - Multi-stage centrifugal pump - Google Patents

Abstract

PURPOSE: To enable the characteristic curve of fluid head to be changed by being dependent upon whether a final stage guide unit for guiding fluid discharged from a final stage turbine into a discharge casing is incorporated or not during the assembling of a multi-stage centrifugal pump.

CONSTITUTION: Liquid discharged from a final stage turbine 12 and guided through guide vanes 2a which are equally spaced and spirally arranged around the periphery of a final stage guide device 2, is collected in a discharge casing 1 and then is discharged therefrom. In this case, since the velocity head of the fluid is effectively changed into a pressure head, the pump has a characteristic corresponding to a characteristic curve A of fluid head shown in the drawings. In case that the final stage guide unit 2 is not incorporated, the liquid is directly introduced into the discharge casing 1 from the final stage turbine 12 and then is discharged therefrom. In such a case, since the liquid passage area is wide due to the elimination of final stage guide unit 2 so that a sufficient volume of the fluid flows, the pump has a characteristic corresponding to a characteristic curve B of fluid head. The presence of the final stage guide unit 2, that is: whether this is incorporated or not during the assembling of the pump, determines its pump characteristic corresponding to either one of the characteristic curve A or B of fluid head.

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