Consulting the P/T chart for R-22 with a suction pressure of 68.6 psig results in a superheat measurement of?

In order to determine the superheat measurement based on a suction pressure of 68.6 psig for R-22, you first need to consult the Pressure-Temperature (P/T) chart for R-22. The P/T chart indicates the saturation temperature associated with any given pressure for refrigerants.

For R-22, a suction pressure of 68.6 psig corresponds to a saturation temperature of approximately 36.5 degrees Fahrenheit. To calculate superheat, you measure the actual temperature of the refrigerant vapor at the suction line before it enters the compressor. Superheat is defined as the difference between this actual temperature and the saturation temperature at the given pressure.

When referencing the correct choice, a superheat measurement of 20 degrees indicates that the actual temperature of the refrigerant vapor is 56.5 degrees Fahrenheit (36.5 degrees saturation temperature + 20 degrees superheat). This value is realistic for typical operational conditions, as it ensures that vapor entering the compressor is adequately superheated, thus avoiding liquid refrigerant issues and improving compressor efficiency.

The other temperatures listed do not align properly with typical operational parameters for R-22 under the given suction pressure, making them less plausible for an accurate measurement. Thus, the value of