Crankcase Pressure-Regulating Valves
Crankcase pressure-regulating valves are designed to prevent the overload of the compressor motor. They limit the pressure in the crankcase of the compressor during and after defrost or after a normal shutdown period. When properly installed in the suction line, these valves supply automatic control of steam leaving the evaporator until the compressor can handle the load. They are available in the range from 0 to 60 pounds per square inch.
Crankcase pressure regulating valve (CRO) is sometimes called suction pressure-regulating valves. They are sensitive only their outlet pressure. This will be the crankcase of the compressor suction pressure. To indicate that the line designation describes the operation as close to an increase in the pressure at the outlet (CRO). As shown in Fig. 11-26, inlet pressure on the bottom of the bellows, and on top of the seat disc. Since the effective size of the bellows equal to the area of the port, the pressure at the input cancels and does not affect the operation of the valve.
The outlet valve
pressure acting on the bottom of the disk exerts a force in the direction closed. This force is opposed adjustable springs. This work force CRO. CRO pressure setting is determined by the force of the spring. Thus, increasing the force of the spring, valve or pressure at which the valve closes increases.
Until valve outlet pressure is greater than the pressure valve, valve remains closed. As the output pressure is reduced, the valve opens and the transfer of the refrigerant vapor in the compressor. Further reduction of pressure on the outlet will allow the valve to open its nominal position, where nominal pressure drop will exist after
valve port. Increase of discharge pressure will cause the valve to regulate not yet reached the pressure setting.
The valve functioning of this type, improved antivirus chatter is a device built into the valve. Without this device, the CRO will be exposed compressor pulsations, which significantly reduce the life of the furs. This feature allows the CRO function at low loads without any communicate or other operational difficulties.