It can be seen that the rate of
corrosion is insignificant below
50% relative humidity and can be
disregarded below 40% relative
humidity.
The rate of corrosion increases
noticeably from 60% relative hu-
midity. This moisture damage limit
applies also to numerous other
materials, e.g. powders, packag-
ing, wood or electronic units.
Buildings can be dried out in differ-
ent ways:
1.
By heating and air exchange:
The room air is heated to absorb
moisture in order to then be
discharged to the atmosphere.
The total input energy is lost
with the discharged, moist air.
2. By dehumidification:
The moist air in an enclosed
room is continuously dehumidi-
fied according to the condensa-
tion principle.
The interrelated processes occur-
ring during dehumidification are
based on physical laws.
These are illustrated here in sim-
plified form in order to explain the
principle of dehumidification.
The use of REMKO
dehumidifiers
– No matter how well windows
and doors are insulated, damp
and moisture can penetrate
even through thick concrete
walls.
– The water volumes required for
binding concrete, mortar, plas-
ter, etc. are diffused out initially
after 1-2 months under certain
circumstances.
– Even moisture that has pene-
trated masonry following high
water or flooding is only re-
leased very slowly.
– This applies similarly to e.g.
moisture contained in stored
materials.
The moisture (water vapour) es-
caping from buildings or materials
is absorbed by the ambient air. This
increases their moisture content
and ultimately results in corrosion,
mould, rot, peeling of paint coat-
ings and other unwanted moisture
damage.
The diagram opposite shows an
example of the rate of corrosion,
e.g. for metal at different humidity
levels.
In terms of energy consumption,
dehumidification has one decisive
advantage:
Energy expenditure is restricted
solely to the existing room volume.
The mechanical heat released
through the dehumidification
process is returned to the room.
With correct use, the dehumidifier
consumes only about 25% of the
energy required for the “heating
and ventilation” principle.
Relative humidity
Ambient air is a gas mixture and
always contains a certain amount
of water in the form of water
vapour. This water volume is ex-
pressed in g per kg dry air (abso-
lute water content).
1m
3
air weighs about 1.2 kg at 20°C
Depending on the temperature,
each kg of air is only able to ab-
sorb a certain amount of water va-
pour. When this absorptive capaci-
ty is reached, reference is made to
“saturated” air; this has a relative
humidity of 100%.
Relative humidity is therefore un-
derstood to be the ratio between
the amount of water vapour cur-
rently contained in the air and the
maximum water vapour volume at
the same temperature.
The ability of air to absorb water
vapour increases with increasing
temperature. This means that
the maximum (= absolute) water
content increases with increasing
temperature.
Dehumidification
corr
osion rate
relative humidity
4
REMKO SLN 40-80
