GB896481A - Improvements in and relating to sealing of centrifugal impeller pumps - Google Patents

Abstract

896,481. Stuffing-box substitutes. MURRAY, W. Sept. 2, 1958, No. 28212/58. Addition to 789,671. Class 122 (5). A seal for a centrifugal pump is formed by arranging for the wall 11 of the pump impeller to partition the impeller chamber in the radial sense and to carry blades 14 serving as seal blades on the side remote from that carrying the working blades 13 and for a member 6 carried by the pump shaft 5 to make rubbing contact with a ring 22 carried by an axiallydisplaceable wall 9 forming the wall of an annular space 16, the rotation of the impeller at sufficient speed being arranged to cause liquid in the seal blade space to be centrifuged away from the shaft 5 in the form of a liquid ring communicating with the annular space 16 and maintaining such a pressure therein that the wall 9 is axially displaced so as to lessen or eliminate the pressure contact between the member 6 and ring 22. The ring 22 is mounted on a member 18 which is fixed to the hub 20 of the member 9 and, when the pump is stationary, is caused by springs 10 to urge the ring against the member 6; liquid pressure in the pump may augment this action. The wall 9 is received in the annular space 16, and a sealing-ring 21 is arranged between the member 18 and a projecting portion 17 of the casing ; a small clearance is provided between the periphery of the wall 9 and the space 16 to provide communication between the seal blade space and the space 16, and notches or slots may also be formed in the periphery of the wall 9. In operation, liquid in the seal blade space is thrown outwardly to form a ring of pressurized liquid which seals the liquid in the pump and, through the peripheral clearance of the wall 9, increases the pressure in the space 16 until the pressure of the springs 10 is overcome and the ring 22 is withdrawn from the member 6; during this movement, the ring 21 performs a rolling movement until it is supported by a shoulder 24 of the member 18. The sealing-ring 21 may be replaced by a diaphragm or bellows and the springs 10 may be dispensed with, use being made of the sealing-ring 21 (or diaphragm or bellows) to exercise the necessary spring action to close the static seal. Specification 789,671 also is referred to.