How to Read the Standard Performance Curve - Air Conditioning

1. Read psychrometer reading at the inlet, and get relative humidity from psychrometric chart. (See figures on next page.)
2. Measure dry bulb temperature at cool air outlet, then find out the difference between inlet and outlet temperatures.
3. Check the relative humidity-to-temperature difference relationship using the graph.
As an example of 17 °C (62.6 °F) temperature difference and 60% relative humidity shown in it, if their crossing point falls within the area between two lines, cooling performance then is satisfactory and proper.