User Manual

17
5
10
15
20
25
30
0
0-5-10 5 10 15 20 25 30 35 40 45 50 55
9,3
10%
5%
20%
30%
40%
50%
60%
70%
80%
90%
100%
15%
5.2.4. PSYCHROMETRIC DIAGRAM
The atmospheric air that surrounds us is a mixture of:
 dry air,
 and water vapour, generally invisible, that may be found in liquid form (condensation).
There exists on the quantity of water vapour (or absolute humidity) a limiting value beyond which any additional quantity of water
vapour immediately turns into liquid water.
This phenomenon is known as “saturation” and is the cause of fog, dew, and condensation on cold surfaces that cool the air in
contact with them.
To represent the state of the air and its evolution in graphic form, Mollier’s psychrometric diagram can be used; it represents ab-
solute humidity versus temperature for different values of the relative humidity.
Absolute humidity (g of water/kg of dry air)
Fog
Saturation curve
Damp air
Temperature (°C)
Example of use:
For air at 21°C and 60% RH, the absolute humidity is 9.3g/kg and the dew point is 12.8°C.