GB790009A - Submersible impeller pump - Google Patents

Abstract

790,009. Centrifugal pumps. HARLAND ENGINEERING CO., Ltd. July 6, 1956 [July 19, 1955; Nov. 16, 1955], Nos. 20939/55 and 32836/55. Class 110 (1). In a pump adapted for use in totally sealed boiler or other circulating systems with the motor and pump impeller mounted vertically one above the other, the shaft is allowed a limited axial movement, and the impeller and the pump housing have radial abutment faces, the space between. which is in communication with an annular passage which itself is in communication with the impeller delivery, a radial gap being provided between a lower part of the impeller and housing and communicating with the delivery, whereby the pump is self-balancing. In the pump shown in Fig. 1, the shaft rests on a thrust bearing 8 until, at part speed, it is lifted clear by the delivery pressure acting on the back 15 of the impeller through a radial gap 16. The upward movement brings an abutment face 9 on the impeller close to an abutment face 10 on the casing, thereby reducing the flow of liquid from the delivery through a constriction 13 and an annular space 12 to the inlet 11. This increases the liquid pressure on the impeller face 9, and a position of equilibrium is reached between this downward pressure and the upward pressure on the back 15, together with gravity forces, with the impeller running on a film of liquid between the faces 9 and 10. Balance holes 17 are provided. The driving motor 25 and the shaft bearings are exposed to the liquid, which lubricates the bearings, through leakage holes 22, 24. Turbulences caused by the moving parts produce circulations as indicated by arrows. In a modification, in which the impeller is inverted and mounted below the motor, the abutment faces and the adjacent annular space are at the back of the impeller and the radial gap corresponding to the gap 16 is at the front of the impeller. The thrust bearing is at the top of the shaft.