Relative air humidity
Our ambient air is a gaseous mixture which always
contains a certain volume of water in the form of
water vapour. This volume of water is specified in g
per kg of dry air (absolute moisture content).
1m
3
of air weighs approx. 1.2 kg at 20 °C
Depending on the temperature, each kg of air is
only capable of absorbing a certain volume of
water vapour. Once this capacity has been
reached, the air is referred to as "saturated" and
has a relative humidity (RH) of 100%.
Relative humidity is understood to mean the ratio
between the current quantity of water vapour in the
air and the maximum possible quantity of water
vapour at the same temperature. The ability of the
air to absorb water vapour increases as the tem-
perature rises. I.e. the maximum possible (abso-
lute) water content becomes greater as the tem-
perature rises.
Temp.
Water vapour content in g/m
3
at humidity of
°C
40%
60%
-5
1.3
1.9
+10
3.8
5.6
+15
5.1
7.7
+20
6.9
10.4
+25
9.2
13.8
+30
12.9
18.2
°C
80%
100%
-5
2.6
3.3
+10
7.5
9.4
+15
10.2
12.8
+20
13.8
17.3
+25
18.4
23.0
+30
24.3
30.3
Drying materials
Building materials and structures are capable of
absorbing considerable volumes of water, such as
brick 90-190 l/m
³
, heavy concrete 140-190 l/m
³
and
limestone 180-270 l/m
³
. The drying of moist mate-
rials such as masonry is effected as follows:
The moisture moves from the inside of the material
to its surface.
Fig. 2: Drying damp masonry
n
Evaporation occurs on the surface = Transfer
of water vapour to the ambient air
n
The air containing water vapour is constantly
circulated through the REMKO air dehumidifier.
The air is dehumidified and, slightly heated,
leaves the unit in order to re-absorb water
vapour
n
In this way, the moisture contained in the mate-
rial is reduced gradually
The material is dried!
The accumulated condensate is collected in the
unit and drained off from there.
Fig. 3: Extracting and collecting condensate
REMKO ETF-S Series
10
