GB582355A - Improvements in and relating to self-priming centrifugal pumping plant - Google Patents

Abstract

582,355. Centrifugal pumps. SOUTHERN, J. June 30, 1944, No. 12487. [Class 110 (i)] A self-priming centrifugal pump unit comprises a centrifugal pump and a priming pump of the vortex type in parallel therewith, so that the vortex pump operates as a vacuum pump during priming of the centrifugal pump and as a liquid pump after priming. A vortex pump is defined in the Specification as a pump in which a whirling ring or vortex of liquid is created by rotating vanes in a peripherally confined space and a stop member in the path of the rotating liquid causes a proportion thereof to be diverted to a lateral delivery, fresh liquid being drawn in through a lateral inlet. In Fig. 1, the vortex pump is constituted by a series of radial vanes 2, formed on the rear face of the centrifugal pump impeller 1, and inclined to the face as shown in Fig. 2, and extending from the hub to a rim 2a which is in sealing contact with an annular projecting portion 5d of a stationary plate 5. Fluid passes from an inlet port 5b to the vanes 2, and is thrown outwardly by centrifugal force into a volute 5a. The stop member 5e prevents complete rotation of the fluid, which is thereby forced inwardly to an outlet port 5c. The volute may be of decreasing cross-section in the direction of whirl or the section may be constant or a combination of parallel and tapered forms. The suction chamber 4d of the centrifugal pump has a lip 4c to trap liquid and keep the suction eye 1a flooded. A suction chamber 6 for the vortex pump is connected by a pipe 7 to the upper part of chamber 4d and also communicates with the centrifugal pump discharge to the rear of a non-return valve 9 through a bye-pass 7a and a duct 7b. The latter may conveniently be formed in the spider of the non-return valve. The vortex pump discharge chamber 8 is connected by a pipe 10 to the main discharge. On starting up, the residual liquid in the centrifugal pump is raised past the non-return valve 9 and passes through passages 7b, 7a and 7 into the inlet chamber 6 of the vortex pump, and is discharged through pipe 10 into the main discharge above valve 9, and then returns to chamber 6 to be recirculated. During priming, the vortex pump withdraws air from suction chamber 4d through pipe 7. On completion of priming, valve 9 seats itself against the orifice of duct 7b, and thereafter the vortex pump acts as a liquid pump in parallel with the centrifugal pump. The centrifugal and vortex pump impellers may be separate, with a partition between them.