GB808081A - Self-priming centrifugal pump - Google Patents

Abstract

808,081. Centrifugal pumps. SIGMUND PUMPS Ltd. May 17, 1957 [June 8, 1956], No. 17845/56. Class 110 (1). In a self-priming centrifugal pump of the kind in which a discharge chamber adjacent the impeller chamber is divided by a dividing member to provide flow passages such that liquid delivered through one of the flow passages may recirculate towards the impeller through the other flowpassage during priming, the liquid being discharged through both passages during normal operation, the impeller axis is vertical and the lower end of the discharge chamber extends around part of the circumferential length of the impeller chamber, and the dividing member extends upwards in the discharge chamber with its upper edge above the plane of the impeller chamber and below the outlet from the discharge chamber. The discharge chamber 15 is bounded by vertical walls 17, 18 concentric with the impeller 12, and at its lower end is divided by an arcuate wall 22 extending upwardly from a horizontal wall 16 which separates the discharge chamber 15 from the suction chamber 2. The wall 22 extends from the end wall 20 of the discharge chamber 15 adjacent the cut-water 21 and has a vertical free end 23. Bracing webs 25, 26 joining the wall 22 to the walls 17, 18 extend from the free end 23 and are of limited length so that apertures 27, 28 are provided between their free ends and the wall 20. During priming, a mixture of liquid and gas passes from the pump intake (not shown) downwardly through a passage 3 to the suction chamber 2, and is delivered by the impeller 12 upwardly through the aperture 27. The gas separates from the mixture and is discharged in the direction A<SP>4</SP> through the outlet 19 of the discharge chamber 15 while the liquid flows over the upper edge 24 of the wall 22 and down through the aperture 28 in the direction A<SP>5</SP> and thence between the walls 16, 26 in the direction A<SP>6</SP>, finally passing in the direction A<SP>7</SP> around the free end 23 to mingle with the mixture of liquid and gas in the impeller chamber 6 to increase the proportion of liquid therein. On completion of priming, liquid delivered by the impeller 12 flows at both sides of the wall 22 in the direction B<SP>2</SP> and then upwardly through the apertures 27, 28 towards the outlet 19. The walls 7, 16, 22, the webs 25, 26 and the cutwater 21 may be formed as a unitary casting which can be replaced when worn. As shown in Fig. 3, two inlet passages 3 may be provided, the inlet not in use being covered by a closureplate.