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___________________________________RAH / PAH Ka_________________________________
2.4 MAIN COMPONENTS
FRAME
The base and the frame are made up of high-thickness galvanized steel elements, assembled with stainless steel rivets. All the external galvanized steel surfaces
are protected by a powder painting of colour RAL 7035 smooth. The structural elements are rmly xed making the frame very strong and able to support all
the unit components and to absorb any mechanical stress due to unit handling and running. The electrical cabinet and compressors technical compartment (if
options CF or CFU is included) are totally closed and separated from the airow. The external panels of the technical compartments are easily dismountable and
positioned on the side of the unit granting an easy access to the main components. Moreover the components are installed inside the structure in such a way to
make any service intervention during the unit operation as well as ordinary maintenance easy and safe.
COMPRESSORS
Compressors are of semi-hermetic screw type, equipped with capacity steps, motor thermal protection, phase monitor, crankcase heater. Compressors
lubrication is of forced type without pump, to avoid excessive oil migrations to the cooling circuit, compressors are equipped with oil separator on discharge side.
The electrical motor is prearranged for low inrush current start and in this case the unit is equipped with an automatic partial load start device and mechanical
interlock of the inrush control switches in order to avoid accidental short circuits (Option DS or PW).
HEAT- EXCHANGE EXTERNAL COILS
Heat- Exchange external Coils with micro nned (ried) copper tubes and aluminium ns with special corrugation for an higher heat exchange efciency. In
the PAH Ka evapo-condensing coils, the ns spacing is high, to avoid a sudden freezing in winter operation with consequential efciency decrease. The nned
exchangers are suitably sized with a wide exchange surface, so to allow the unit operation also at very high external air temperatures in summer operation and
low ones in winter operation. In case of installation in very aggressive environments, several coil protection treatments are available on demand.
USER SIDE EXCHANGER
Shell & tube exchanger of dry expansion type with pure electrolytic copper tubes and plate carbon steel shell. The exchanger is equipped with a condensa-
tion-proof insulation, made by close cell polyurethane foam material as well as an external UV ray-resistant and scratch-proof cover. Inside the shell some
plastic corrosion-proof bafes are suitably placed. They favourite a right water distribution and make the tube bundle particularly strong and vibration-free, even
with very high water ows. The exchanger design pressure (waterside) is 10 bar.
AXIAL FANS
The fans, servicing external heat-exchanger coils, are of axial type, with directly coupled three-phase totally closed electric motor. They have got IP54 protection
degree, class F and are provided with internal thermal protection which is drowned in the electrical motor winding. The aluminium blades have got a peculiar
prole geometry designed to minimize the turbulences in the air detachment zone (reducing in this way the sound level and increasing efciency). Each fan is
equipped with suction nozzle and safety protection grid, painted after construction.
In the low noise version (RAH S Ka), in order to reduce the sound level, the electrical connection is of star type, reducing thereby the rotation speed and con-
sequently the air ow to the coil.
It is also possible requiring axial fans with electronic commutation (Option EC- only for RAH Ka series) which allow a continuous speed regulation through a
0-10 Volt Signal completely managed by the microprocessor. With this kind of fans the airow on the condensing coil is regulated with an higher precision, and
this allows the unit to work with external air temperature till -20°C keeping unchanged the cycle high efciency.
COOLING CIRCUIT
Each cooling circuit of RAH/PAH Ka series is equipped with:
• Filter drier;
• Sight glass;
• Electronic thermostatic valve (in PAH Ka series, it works in winter operation only);
• Mechanical thermostatic valve (in PAH Ka series, it works in winter operation only);
• PED approved liquid receiver (for PAH Ka series only);
• Suction side liquid separator (for PAH Ka series only);
• 4 ways cycle inversion valve (for PAH Ka series only)
• Certied (if required) high pressure valves;
• Shut-off valve on liquid line;
• High and low pressure gauges;
• High and low pressure switches;
• Temperature probes to evaporator in and outlet.
The above mentioned components are connected in a close circuit through copper pipes and connections. The permanent junctions among components are
made by brazing or welding, following qualied processes and made by qualied personnel.
