Balance Piston

An internal component in a centrifugal pump or centrifugal compressor designed to counteract the thrust force on the rotor developed by the pressure rise generated by the impellers. Thrust balancing is accomplished by subjecting the outside of the balance piston, i.e., the side away from the process, to a lower pressure from the suction side of the compressor, thereby creating a pressure differential opposite the direction of the impeller-generated thrust force. The low-pressure region is achieved by connecting the area behind the piston to the suction using a balance line. The impeller thrust not balanced by the balance piston must be absorbed by the thrust bearings.