The maximum moisture content possible in air - at saturation - varies with temperature. The table below indicates maximum moisture content in a cubic metre of air at various temperatures:

Temperature Max.

Water Content (oC) (oF) (10-3 kg/m3) (10-3 lb/ft3) -25 -13 0.64 0.040 -20 -4 1.05 0.066 -15 5 1.58 0.099 -10 14 2.31 0.14 -5 23 3.37 0.21 0 32 4.89 0.31 5 41 6.82 0.43 10 50 9.39 0.59 15 59 12.8 0.8 20 68 17.3 1.07 30 86 30.4 1.9 40 104 51.1 3.2 50 122 83.0 5.2 60 140 130 8.1

10-3 kg/m3 = g/m3

Example - Moisture Carrying Capacity in Heated Air

Air is heated from 20oC to 50oC.

from the table above the maximum moisture content in air at 20 o C is 17.3 g/m 3 , and


C is 17.3 g/m , and the maximum moisture content in air with temperature 50oC is 83 g/m3

The increased ability to carry moisture can be calculated as

100 % ((83 g/m3) - (17.3 g/m3)) / (17.3 g/m3)

= 380 %

This dramatic change is important to explain why heated air is so much more effective than cold air in drying processes.