Way Technovation -
The
Humidity
Control Specialist |
Introduction to the Process of
Dehumidification-
Here are the answers to why that there is a need for dehumidification:
It also deals with questions like : Where does the moisture come from ?
Does it help if I throw a pack of silica gel in my drawers ?
Does Heating up a place reduces the moisture ?
|
Why
dehumidification?
|
|
Corrosion
Iron and steel will not rust if the air in
contact with the surface has a relative humidity below 50% relative
humidity (RH). Dehumidification is often a better and less expensive
way to protect investments than painting is. Objects that are
protected by dehumidification are for example bridges, power
stations , boats (during standstill) and off-shore constructions.
|
|
|
Condensation
Moisture will not condensate on a surface if the
air in contact with it has a dew-point lower than the surface
temperature. Condensation can lead to many problems such as
corrosion or short-circuit in electrical systems.
|
|
|
Ice formation
Ice will not form on a surface if the air in
contact with it has a dew-point lower than the surface temperature.
Ice formation is a problem in for example cold storages where it
will cause a lower efficiency in the cooling machinery.
Dehumidification will keep the ice away.
|
|
|
Handling of hygroscope materials
The quality of dry drugs, dry food, hard candy
and other hygroscope materials can only be maintained through
production to the consumer if it is kept in contact with air at a
low relative humidity. If your products form lumps, degrade quickly,
or get sticky you should consider dehumidification. Most materials
demand dew-points so low that they can only be achieved by sorption
dehumidifiers.
|
|
|
Drying buildings
When drying moisture from a building, whether it
is a new building or a building with water damages, the most
effective way is to use sorption dehumidifying. Heating will only
move the moisture to another part of the building, heating in
combination with outdoor ventilation will create high energy costs.
With sorption dehumidifying the moisture is moved out of the
building in a very energy efficient way.
|
|
|
Mould
Mould and fungus formation is prevented if the
surrounding air is kept below 70%RH. This is important in many
situations, for example in storage of wooden products. In houses
designed with a crawl space it is often necessary to use a
dehumidifier to keep mould and fungus from forming.
|
|
|
Product drying and cooling
When drying and cooling products a low relative
humidity is essential for a fast process. If the products to be
dried are sensitive to high temperature, the low relative humidity
can only be obtained with dehumidification. In cooling processes
dehumidification allows for a lower temperature without
condensation. The result is faster cooling and money saved.
|
|
|
Bacteria
Bacteria need humidity to survive and multiply.
Often the humidity required for bacteria to multiply is found on
hygroscope materials. If the surrounding air is held below 50%
relative humidity most bacteria will not find a suitable environment
to multiply.
|

|
|
Odors
Bad smell will drastically be reduced if the
relative humidity is kept below 50%RH. In for example sewage
stations the odor can often be controlled by installing a
dehumidifier.
|
|
|
Click the following for the answers to the questions:
How does a
dehumidifier (DH) reduce moisture ?
What is
Relative Humidity ( or RH ) ?
What is
Absolute Humidity ?
How to
calculate Humidity load in general cases
?
|
 |
Dehumidification is an on-going process to reduce and keep the
air moisture low.at an enclosed space.
How does moisture come into the space ? Normally, there is a
certain air getting into the space via cracks or gaps
( Infiltration)
, or even through the wall (Permeation). Human being gives moisture
through' breathing and evaporation
from the skin too. If the place stores things that give
up water like plants, wet towers, exposed water containers, wet sink
etc. In the
basement of buildings, usually there are more moisture problems than other floors. This is
caused by moisture
in the earth below and surrounding the walls of the basement. Though
concrete wall is supposed to be able to keep water
from flooding in, moisture permeation
has a very high power draw to penetrate even this thick walls. As long as there is a
small
opening, more humid air will flow into the areas with lower humidity. This is a physical
process calls Diffusion. The
Rate of Diffusion ( or the speed of molecular
movement ) is determined by the vapour pressure difference between the
two spaces. A high
moisture concentration constitute higher vapour pressure.
 |
If the space is left alone, the
infiltration, permeation and other moisture contributing process will take place until the
space reaches an equilibrium "wetness" ( or Humidity ) level that these process
no longer take place. This level of wetness may usually be too damp for the equipment
which may cause damage or human discomfort. ( see Dehumidifier
Applications ) To get rid of this moisture, some form
of Dehumidification process is needed to remove the moisture. As the moisture infiltration
is process is a continuous one, by putting in a pack of silica gel
usually does not work for a long time. Silica gel is a well known
moisture absorbing material. It sucks up moisture like a sponge !. However, it will stop
working once it is SATURATED. It does not suck up moisture forever ! That's why some
camera box silica gel has blue (when dry) / red (wet) colour indication
feature. Silica Gel, however, is very useful and cost effective for tight sealed packed
product which has water proof skin like plastic or aluminium foil. |
Heating as a form of reducing relative humidity is found in simple devices like a
piano heater, or instrument box /cabinet with built-in heaters. Heating raises the space
temperature and thus at the same moisture content of a space lower the relative humidity.
It has, however, never removed a single droplet of moisture from the air ! It is
relatively workable in cool and dry countries. Its effectiveness in hot and humid
countries not as good. The good news is, the moisture damaging effect on product is
proportional to the Relative Humidity of the Space rather than the actual amount of
moisture content
( Absolute Humidity ).
|
 |
Some of the modern bridges with welded box construction on cold
countries are protected against corrosion by the help
of dehumidifiers, saving a lot of
maintenance. Another area will be in the marine application. Ships are very sensitive to
moisture. Partly due to the salty atmosphere and partly caused by the vast temperature
fluctuations. The upper deck
which is exposed to the air may be tens of degrees different
in temperature compared to the lower part which is touching
the sea water. This variation
usually causes large humidity differences and resulted in condensation of water on the
metal
surface. Dehumidifiers are usually used to keep the air dry.
|