GB1290635A - - Google Patents

Abstract

1290635 Centrifugal pumps RED JACKET MFG CO 27 May 1971 [15 June 1970] 17578/71 Heading F1C In a multi-stage diffuser-type centrifugal pump, each stage has an annular rubber member and an annular stainless steel member in sealing engagement with each other to reduce backflow of liquid and to provide a radial bearing, one of the members being mounted rearwardly of the rear impeller wall for rotation with the drive-shaft and impeller, and the other member being mounted on a non-rotatable diffuser wall. Fig. 8 shows one arrangement in which each stage has a stainless steel journal 102 mounted either directly on the shaft 22 or, as shown, on an extension 38α of the impeller hub 38 and co-operating with a rubber bushing 103 mounted on a diffuser wall 56. The bushing 103 acts as a radial bearing and as a seal, and is tapered as shown to dislodge sand or grit coming between the bushing and the journal. The members 102, 103 may be transposed, and the member 103 may be straight instead of being tapered. Each impeller 28 may be of plastics material, the front wall 42 being a separate moulding attached to the main moulding by pegs 46 engaging holes 48, the two mouldings being held together by the fluid-pressure conditions. Instead of abutting each other as shown, the impellers 28 may be spaced apart so that they are free to float axially into a state of hydraulic balance. A thrust washer (82), Fig. 2 (not shown), is then provided on the impeller front wall (42) to co-operate with a stainless steel wear ring (78) carried by a diffuser wall (54).