At an evaporator temperature of 38 degrees Fahrenheit, what should be the suction pressure for R22 refrigerant?

For R22 refrigerant, the suction pressure is directly related to the temperature of the evaporator due to the refrigerant's phase change characteristics. At a specific temperature, the refrigerant will have a corresponding saturation pressure, which indicates the pressure at which it vaporizes for that temperature.

At an evaporator temperature of 38 degrees Fahrenheit, the saturation pressure for R22 refrigerant can be referenced from a refrigerant temperature-pressure chart or tables. For R22, the saturation pressure at 38°F is typically around 66 PSIG. This means that in order to maintain proper operation in the evaporator, the suction pressure should ideally be around this saturation value.

Maintaining the suction pressure at this level ensures efficient heat absorption in the evaporator, avoiding issues like compressor overload or reduced system efficiency. The other choices listed are either too high or too low compared to the established saturation pressure for R22 at the given evaporator temperature, making them unsuitable for effective operation.