How do you calculate discharge superheat on a chiller?

To calculate discharge superheat on a chiller, first measure the discharge temperature of the refrigerant at the compressor outlet. Then, determine the saturation temperature corresponding to the refrigerant pressure at the same point using a pressure-temperature chart. Subtract the saturation temperature from the discharge temperature; the result is the discharge superheat. For example, if the discharge temperature is 120°F and the saturation temperature at the corresponding pressure is 100°F, the discharge superheat would be 20°F.