GB863527A - Improved fluid sealing device - Google Patents

Abstract

863,527. Stuffing-box substitutes. ALLISCHALMERS MANUFACTURING CO. Nov. 9, 1959 [Nov. 17, 1958], No. 37968/59. Class 122 (5). A fluid sealing device 19 between the shaft 14 of a centrifugal pump 11 and its housing 16 comprises an annular member 21 mounted on the shaft for axial movement relative thereto under the action of a pressure differential on the end faces 34, 38 and 42 of the member so as to provide an end sealing gap 37 between the faces 34, 38 and the face 36 of a stationary member 32, and an axial sealing gap 24 provided between the member 21 and the housing 16 in fluid communication with the end sealing gap and in series therewith in the direction of fluid flow between the zones of different pressures so that, in operation, fluid flows from the zone of high pressure acting on the end face 42 through the axial sealing gap 24 to the end sealing gap 37 and thereby maintains the latter at a constant dimension. The axial sealing gap 24 is defined between the annular member 21, which is coupled by a bellows 22 to a member 17 secured to the shaft, and a number of radially movable rings 27 which together form a labyrinth-type seal for determining the pressure differential between the two end faces 42 and 34, 38 of the annular member. In operation, when the pump is started, fluid passes through the gap 24 into a chamber 39 where the pressure of the fluid then builds up until it equals that acting on the end 42 and since the area of the face 38 of the annular member is arranged to be greater than the area of the end face 42, the surface 34 is lifted away from the surface 36 of the member 32. The fluid then flows through the gap into a low-pressure zone 46 thereby causing the pressure in the chamber 39 to drop below that acting on the end 42 but since the surface area 34 is now additionally subjected to this pressure, the gap 37 is maintained constant. Instead of using the fluid medium being pumped as the sealing medium, a fluid medium may be introduced for this purpose at a pressure above that of the pump system.