A spring-loaded relief valve is installed in the compressor discharge line as an additional precau-tion against excessive pressures. The relief valve is set to open at approximately 225 psig. Therefore, it functions only in case of failure or improper setting of the high-pressure cutout switch. If the relief valve opens, it discharges high-pressure vapor to the suction side of the compressor.

WATER REGULATING VALVE

A water regulating valve controls the quantity of cooling water flowing through the refrigerant condenser. The water regulating valve is actuated by the refrigerant pressure in the top of the con-denser. This pressure acts upon a diaphragm (or, in some valves, a bellows arrangement), which transmits motion to the valve stem. The primary function of the water regulating valve is to maintain a constant refrigerant condensing pressure. Basically, two variable conditions exist: (1) the amount of refrigerant to be condensed and (2) changing water temperatures. The valve maintains a constant refrigerant condensing pressure by controlling the water flow through the condenser. By sensing the refrigerant pressure, the valve permits only enough water through the condenser to condense the amount of refrigerant vapor coming from the compressor. The quantity of water required to condense a given amount of refrigerant varies with the water temperature. Thus, the flow of cooling water through the condenser is automatically maintained at the rate actually required to condense the refrigerant under varying conditions of load and temperature.