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1. GENERAL SAFETY INFORMATION
•
Anyone operating the DHA 160/DHA 250 should have access
to this manual, and should be aware of the safety information.
•
Only personnel with adequate knowledge of the dehumidifier
should be allowed to operate and service it.
•
Only personnel with authorisation for electrical installations
are allowed to make repair of electrical components.
•
Repair of electrical components should be carried out by
suitable qualified personnel.
•
The dehumidifier must not be installed in areas where
explosion proof equipment is required.
•
Disconnect the dehumidifier from the mains prior to opening
any service panel.
•
Prior to servicing the dehumidifier must be left to cool down
for at least 15 minutes after operation.
•
The service panels should remain closed except when
serviceing is carried out.
•
The dehumidifier can only be used for dehumidification of air
at atmospheric pressure.
•
Never use the dehumidifier without the filters as the desiccant
rotor can become contaminated and lose capacity.
•
Signs and instructions on the dehumidifier should not be
removed or altered.
•
This manual should always be accessible and kept close to
the dehumidifier.
•
All maintenance and control of the dehumidifier should be as
per the specified schedule.
•
Use only genuine spare parts.
2. APPLICATIONS
Dehumidifier DHA 160/DHA 250 is of the solid desiccant wheel
type designed to dry air of atmospheric pressure. The
dehumidifier can be used for drying air of up to 100 % relative
humidity (RH) with temperatures from -30 ºC to +40 ºC.
The applications are numerous and wide spread.
Below are some examples:
•
Controlling humidity levels in production processes.
•
Drying of temperature sensitive products.
•
Maintaining correct humidity in storage areas.
•
Protection of equipment sensitive to corrosion.
•
Controlling humidity levels in museums and archives.
•
Drying after water damage and drying of buildings during
construction.
•
Climatic improvements in damp areas.
3. METHOD OF OPERATION (Fig. 3.)
The dehumidifier operates with two air streams. A larger air
stream to be dehumidified, and a smaller air stream to exhaust
the moisture out of the desiccant rotor.
Both airstreams are created by one common fan which
pressurises a compartment of the dehumidifier creating two
separate airstreams.
The larger air volume, the process air, passes through the slowly
rotating silica gel rotor. Silica gel is a hygroscopic material
adsorbing water vapour direct from the air. When passing
through the rotor the humidity of the air is reduced, whilst the
moisture content of the rotor material increases. On exiting the
rotor the dried air is introduced into the area, or the process to be
dehumidified. The adsorption process works in temperatures
from -30 ºC to +40 ºC.
The smaller air volume, the reactivation air, adsorbs the moisture
from the silica gel rotor. This reactivation air first enters a purge
sector of the rotor, thus cooling down the rotor material, and
simultaneously increasing the reactivation air temperature. The
temperature of this preheated air is further increased by an
electrical heater to a temperature of approximately +100 ºC. As
the reactivation air passes through the rotor, in an opposite
direction to the dry air, it will decrease the moisture content of the
rotor material. The reactivation air will leave the dehumidifier as
warm, wet air, which is then exhausted out from the building.
4. PRODUCT DESCRIPTION
The dehumidifier is designed to meet the requirements of IEC
protective class IP 44:
Casing
The casing is fabricated from stainless steel 2333. The top of the
dehumidifier has a top panel that can be removed for service
access to electrical and mechanical components. All duct
connections to the dehumidifier are designed for connections to
standard size spiral ducts.
Rotor
The dehumidifier has a drying rotor fabricated from a desiccant
material. The rotor has a matrix of corrugated and flat heat
resistant sheets which houses the Silica Gel desiccant agent.
This matrix creates a large number of axial flutes through the
rotor, which together builds up an immense surface area for
moisture adsorption in a small volume. The rotor is manufactured
and processed to be able to withstand moisture saturated air
without being damaged. This means that the rotor can be used in
conjunction with a pre-cooling coil. Furthermore the rotor will not
be damaged even if the fan or the heater for reactivation should
fail during operation. The rotor is incombustible and non
flammable.
The slow rotation of the rotor is achieved by an electrical gear
motor and a belt drive. The belt sits on the outer rim of the rotor
and is driven by a pulley on the drive motor. An adjustable belt
tension device keeps the belt in place and maintains tension to
prevent belt slip. Correct operation of the drive system, and
direction of rotation can be checked by opening the top panel.
The centre hub of the rotor is equipped with ball bearings. The
rotor shaft is made from stainless steel. The complete rotor part
can easily be removed and lifted as one piece out from the
casing.
Filter
The dehumidifier has one common filter for process- and
reactivation air.
Fan for process- and reactivation air
The fan is a direct drive radial fan with a single phase standard
motor class IP 54, ISO F. The fan is accessible for service after
removing the top panel of the dehumidifier.
Heater for reactivation air
The reactivation heater is of the PTC-type (Positive Temperature
Control), which can not be overheated, and gives the possibility
of a stepless control for 30 - 100 % of the dehumidification
capacity. This is achieved by controlling the wet air volume.
Electrical panel
The electrical panel is located inside the dehumidifier and is
accessible through the top panel. Switches and indications for
operation are mounted at the front of the electrical panel.
Operation options
Using the operation switch on the front side of the dehumidifier,
different running options can be selected:
0
Dehumidifier not in operation.
1
Dehumidifier in operation mode.
MAN
Dehumidifier in continuous operation.
Automatic operation by remote humidistat,
AUTO
or other external on/off signal.
5. INSTALLATION
Installation and service access
Dehumidifier DHA 160/DHA 250 is designed for indoor
installation. The dehumidifier should be installed horizontally.
All components in the dehumidifier are accessible from the top of
the unit. For inspection and service, a space of 400 mm must be
left free above the dehumidifier to accommodate for servicing of
filter, fan and rotor.
When using a mounting plate, the dehumidifier must be put so
that the rotorshaft still is horizontal and the wet air outlet is placed
low.
Duct connection for permanent installation
The dehumidifier can be installed in the room that should be
dehumidified or in a separate plant room.
To obtain the best performance the outlets from the fans should
be equipped with diffusors.
Wet air duct out from dehumidifier
The wet air from the dehumidifier should be exhausted to the
outside. The duct should be as short as possible to minimise the
chance of condensation of the wet air. This duct should slope
down slightly to stop any condensed water from flowing back into
the dehumidifier.
If the wet air duct is extremely long, or must be installed sloping
upwards from the dehumidifier, it should be insulated and have
a drainage point (2 mm) drilled at its lowest position.
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