GB961497A - Improvements in pumps - Google Patents

Abstract

961,497. Centrifugal pumps. I. C. JENNINGS. Oct. 18, 1962 [Nov. 29, 1961], No. 39520/62. Heading F1C. A centrifugal pump is located within a receiver and close to the top wall of the receiver, a vertical suction pipe being connected at its upper end to the pump inlet and terminating at its lower end close to the bottom wall of the receiver, control means starting the pump when the liquid level in the receiver reaches an upper limit substantially level with the top of the pump casing and stopping the pump when the liquid level reaches a lower limit at or slightly above the lower end of the suction pipe, and means are provided for venting air trapped within the pump and suction pipe as the level in the receiver rises from the lower limit to the upper limit whereby to ensure priming. A motor-driven centrifugal pump 14 is attached to the underside of a cover plate 12 of a sump 10 and draws liquid from the sump through a suction pipe 23 which may be provided with a strainer 61. A switch 34 operated by a float 30 starts the driving motor when the liquid in the sump reaches an upper level 48 and stops it when the liquid falls to a lower level 46. The pump 14 is submerged in the liquid only when the liquid is at or near its upper level 48, and the pump bearings are always above the liquid. When the pump is stationary and the liquid level is rising, air trapped in the suction pipe 23 and in the pump escapes through the discharge pipe 50 and also through vents 36, 38, 40 and thence through a vent pipe 44 to atmosphere. The pump is therefore always primed when it begins to operate. A check valve 54 may be provided in the discharge pipe.