Liquid-chilling systems cool water@ brine or other secondary coolant for air conditioning or refrigeration. The system may be either factory-assembled and wired or shipped in sections for erection in the field. The most frequent application is water chilling for air conditioning@ although brine cooling for lowtemperature refigeration and chilling fluids in industrial processes are also common. Thc basic components of a vapor-compression@ liquid-chilling system include a compressor@ liquid cooler (evaporator)@ condenser@ compressor drive@ liquid-refrigerant expansion or flowcontrol device@ and control center; it may also include a receiver@ economizer@ expansion turbine@ and/or subcooler. In addition@ auxiliary components may be used@ such as a lubricant cooler@ lubricant separator@ lubricant-return device@ purge unit@ lubricant pump@ refrigerant transfer unit@ refrigerant vents@ and/or additional control valves