GB404829A - Improvements in or relating to centrifugal pump structures - Google Patents

Abstract

404,829. Centrifugal &c. pumps. WITHERS, J. S., 51, Chancery Lane, London. -(Jaeger Machine Co. ; Columbus, Ohio, U.S.A.) March 21, 1933, No. 8532. [Class 110 (i).] A self-priming centrifugal pump has a container for priming fluid arranged adjacent the impeller chamber and a port leading from the container to the suction chamber ; the port is controlled by a valve which when closed substantially excludes priming fluid from the suction chamber and when open entirely uncovers the port. The pump casing 1, Figs. 2, 3, has an intake port 2 at the top of the suction line 4 controlled by a check valve 3, and a delivery port 5. The impeller 9 is housed in a volute chamber 6 eccentrically disposed in the casing and having a discharge outlet 7 located at the bottom of the priming liquid compartment 13 which extends along the side and top of the impeller chamber. A suction chamber 16 is arranged inside the compartment 13 and communicates with the impeller by the opening 17 and has a port 18 in its base which can be closed by the plate 21 working on a rubber hinge 22. This plate has a laterally projecting toe 24 in the path of the discharge from the impeller casing outlet 7. When it is desired to start the pump, the plate 21 is in its lowered position as shown in Fig. 3, and the rotation of the impeller draws priming liquid through the port 18 and the elbow pipe 20. This liquid is then discharged through the outlet 7 into the priming compartment to pass again through the passage 18. While there is an undesirable quantity of air from the suction pipe mixed with this circulating fluid the position of the plate 21 remains unchanged, but when the air is discharged and the head at the discharge outlet 7 reaches a predetermined value the plate 21 is lifted to its upper position across the base of the chamber 16 and the pump runs normally. A small opening 23 in the plate 21 still permits communication between the priming and suction chambers and facilitates the opening of the valve when the pump needs priming. The main stream of liquid passes through the discharge port 5 but a portion is circulated over the impeller chamber to stir up any mud that may have settled. Liquid discharging from the jet opening 8 in the side of the impeller chamber also assists this action. In the modification shown in Figs. 5, 7 the priming fluid compartment 36 is arranged above the pump 30, and communication between the compartment 36 and the suction chamber 38 is controlled by a valve 44, which is held open by the weight 46 to permit priming of the pump to occur. After passing through the pump, the priming fluid is returned to the compartment 36 by the duct 35. When the predetermined velocity head from the suction line 41 is reached, the pressure on the plate 47 overcomes the force exerted by the weight 46 and the valve 44 moves to its closed position as shown in Fig. 5 ; the pump then works normally. In another modification the passage between the priming liquid compartment and the suction chamber is controlled by a cylindrical valve operated from outside the casing by a piston subject to the pressure of the suction chamber acting against the force exerted by a spring. A spring pressed plunger ensures that the valve shall rest in its open or its closed position. The cylindrical valve may be replaced by a butterfly valve. In another modification the valve is operated by a rod attached to a diaphragm in a chamber connected by a pipe to an extension of the suction chamber. When the velocity head in the pump is insufficient for proper working, the diaphragm, assisted by a coil spring, moves to open the valve to permit the circulation of priming fluid.