Page 3 - Dry air for safe process design

Humidity, brief and dry.

Depending on the temperature of the air, only a limit-
ed amount of water can be absorbed. The rule is that
warm air can absorb more water than cold air. The
absolute humidity x is given in mass of water per
amount of dry air.

The liquid content of the air, from which no more liquid
can be absorbed at a certain air temperature, is called
saturation, and corresponds to a relative humidity of
100 % (see temperature-humidity diagram below).

Since each temperature along the saturation line can
be assigned an absolute moisture value, the satura-
tion or dew point temperature can also be specified Moisture denotes the content of liquid, e. g.
for an explicit description of the liquid content. This is water, in a substance or gas. In industrial
particularly advantageous when the moisture content practice, it is mostly about the water content
is low (e. g. < 1 g/kg). of the process air or a product.

Temperature-humidity diagram

Water content 30 g/kg 100 % relative 34,4 g/m 3 Absolute moisture

humidity
25 g/kg (saturation) 28,7 g/m 3

No further water
absorption possible
20 g/kg 23,0 g/m 3

Cooling leads to con-
15 g/kg densation of water as 17,2 g/m 3
drops or mist 50 % relative
humidity

10 g/kg 11,5 g/m 3

If the water content is less
than 1 g/kg, only the dew Heating or drying
point temperature is an lead to a lower
5 g/kg illustrative moisture value relative humidity 5,7 g/m 3

0 g/kg 0,0 g/m 3
–20 °C –10 °C 0 °C 10 °C 20 °C 30 °C
Air or dew point temperature

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