Abstract: Centrifugal pumps for handling acids or slurries incorporate a ball bearing assembly as the force-responsive governor to control opening and closing of a fluid path leading from the expeller region into a seal, the seals being composed of hard, low-friction sealing materials for handling acids and of resilient materials for handling slurries owing to the solids content in the slurries.

Abstract: A centrifugal pump of the hydraulic sealing type has a novel and improved sealing apparatus for establishing a hydraulic seal and limiting the flow of liquid from a pump casing into a reservoir or seal housing at one end of the pump casing, and a valve assembly in the seal housing has a valve member normally urged into engagement with the seal housing to isolate liquid in the seal housing from the casing when the pump is not in operation. When the pump is activated and brought up to speed, centrifugal force-responsive pivot members are operative to move the valve member away from sealed engagement with the seal housing to establish fluid communication between the seal housing and pump casing. The force-responsive pivot members are fully enclosed so as to be completely isolated from the liquid in the seal housing and yet be capable of operating directly in opposition to the resilient or spring-loaded valve to move the valve away from sealed engagement with the seal housing.