GB645245A - Improvements in or relating to liquid sealed centrifugal pumps - Google Patents

Abstract

645,245. Centrifugal pumps ; stuffing-box substitutes. LA BOUR, H. E. July 12, 1948, No. 18735. Convention date, April 9. [Classes 110(i) and 122(v)] The rotor shaft 4 of a centrifugal pump extends through a stationary sealing sleeve 7 which terminates in an annular flange 9; the shaft is connected to a sealing drum 37 which carries two sets of liquid working blades 39, 41. The blades 41 open out to the full inner diameter of the drum 37 so that the clearance 42 between the flange 9 and the inner periphery of the drum constitutes the sole restriction to flow of liquid between the two sets of blades. The drum 37 carries impeller blades 6 which operate within a cylindrical housing 1. The latter is clamped between annular seats 18 and 15 formed on upper and lower casing members 2 and 3 respectively. The sleeve 7 is clamped to the upper casing member 2 in a fluid-tight manner by means of a nut 34 and packing 8. A priming charge of liquid initially stands halfway up an intake trap 13. When the pump starts, liquid is expelled through ports 22 and returns through ports 19. The circulation of liquid continues until the air has been removed from the suction passages, after which all the ports serve for the discharge of the pumped liquid through throats 20 into an annular discharge trap 21. A hinged flap 30 retards the backward flow of liquid which occurs when the pump is stopped. The sealing blades 39 and 41 and the clearance 42 provide an annular body of liquid, U-shaped in cross-section, which acts as a liquid seal on the suction side of the pump. The blades 41 are made less effective than the blades 39. For this purpose, the blades 39 have a forward curvature at their inner ends, and the blades 41 either have a backward curvature or are fewer in number than the blades 39. The arrangement may be such as to cause a constant or occasional outrun of liquid through the sleeve 7. The housing 1 may be of the volute type described in Specification 537,015. Specification 559,086 and U.S.A. Specification 2,367,032 also are referred to.