ABSTRACT
A new impeller-to-sump seal was developed for a line of hermetically sealed high-speed (34,000 rpm) refrigerant centrifugal compressor units. By using an actual compressor unit as the heart of the development test rig, experiments were designed to simulate actual in-service operating conditions. Both, the new seal configurations and the original seal were tested. The single-stage compressor needs two high-speed dynamic seals. One seal separates the compressor discharge from its inlet suction side and is a standard stationary labyrinth bushing, which closely encircles the outside diameter of the impeller eye. The seal configurations tested evolved as the project progressed, starting with the existing seal configuration already employed in the product. The original seal was a simple cylindrical rotating piece closely circumscribed by a nonrotating non-sharp-tipped-tooth labyrinth bushing. The annular chamber between the two seal stages vents R-12 back to the impeller eye, which was expected to yield a near-zero pressure difference across the seal's second stage.
