Abstract: Refrigerant gas at a few psi higher than suction is supplied via labyrinth or annular groove type seals located between the suction side bearings and suction and between the suction side motor bearing and the motor. The buffer gas flow divides with part going to suction and part to a drain along the oil flowing from the bearings.

Abstract: An improved transmission vent system for centrifugal compressors comprises a motor compartment, a transmission chamber, an impeller for moving refrigerant in a downstream direction, a guide vane located upstream of the impeller, and a vent pipe connected between the transmission chamber and an area upstream of the impeller and downstream of the guide vane. Refrigerant can be vented from transmission chamber to the area upstream of the impeller and downstream of the guide vane in order to eliminate the pressure differential between the transmission chamber and the compressor suction area upstream of the impeller during start-up.

Abstract: A centrifugal compressor is provided with a collector for receiving refrigerant from the diffuser, and sound absorbent silencer segments are placed within the collector and retained in place against one wall thereof. The silencer segments are held in place by machine screws that penetrate graduated openings in the side wall of the collector. The machine screw shaft fits a threaded nipple on the silencer segment that also fits into the opening. A sealing plug is disposed in a wide part of the opening above the machine screw head to prevent leakage of the compressed refrigerant.

Abstract: The normal path for the flow of oil/refrigerant being reclaimed from the cooler is changed during periods of low load operation such that the oil/refrigerant mixture flows directly from the cooler to the ejector rather than by way of normal suction housing pass. This is accomplished by valve means responsive to either a pressure differential or the guide vanes position, either of which is indicative of the load condition.

Abstract: A labyrinth seal is provided to isolate the transmission from a balance piston of a centrifugal compressor, the labyrinth seal being pressurized with refrigerant vapor from the motor chamber, which vapor is at a pressure slightly above that in the transmission, to thereby minimize the efficiency losses that would otherwise occur from leakage of the vapor into the transmission and to the compressor suction.