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It is strongly recommended to perform installation and maintenance with other people.
In case of accidental injury or unease, it is necessary to:
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Keep calm.
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Press the alarm button if present in the installation site.
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Move the injured person to a warm place far from the unit and in place him or her in the recovery position.
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Immediately contact any emergency personnel in the building or the call the Emergency Services.
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Wait until emergency personnel arrive and do not leave the injured person alone.
3.2
Unit description
The machine is made up of a latest generation, high efficiency, new VVR series single screw compressor, flooded shell and
tube evaporator with the refrigerant outside the tubes and the water to be cooled flowing inside the tube.
A shell and tube condenser where the refrigerant condenses outside the tubes while the cooling water flows inside of the
high-efficiency tubes.
The compressor is of the mono screw semi-hermetic type and utilizes the suction gas coming from the evaporator to cool the
motor and permit the optimum operations in all machine load conditions. The compressor, controlled by inverters, changes
its cooling load according to the rotational speed decided by the controller. In this way the machine perfectly adapts to
system operating conditions to maximize performance.
The oil injection lubrication system, in addition to allowing normal moving part lubrication, also seals the screw ensuring gas
compression, without the aid of an external oil pump.
The cooling circuit also installs an electronic expansion valve that, in addition to managing the level of refrigerant in the heat
exchangers and guaranteeing the correct operation of the compressor, also manages the PUMP-DOWN function.
All the described components are managed by an innovative microprocessor control system that, by monitoring all the
machine operating parameters, optimizes operations.
A diagnostic system helps the operator in identifying alarm and fault causes.
Before starting the compressors ensure that all valves are open and the closing caps are
repositioned and tightened.
3.3
Cooling cycle description
The low temperature refrigerant gas coming from the evaporator is sucked by the compressor and flows through the electric
motor, cooling it. It is subsequently compressed and during this phase the refrigerant mixes with the oil, injected in the
compressor, from the separator.
The high-pressure oil-refrigerant mixture is introduced inside the three-stage high efficiency oil separator which performs the
separation. The oil deposited on the bottom of the separator is sent, by pressure difference, to the compressor again while
the refrigerant separated from the oil is sent to the condenser.
The refrigerant fluid inside the condenser, which crosses the heat exchanger pipes in countercurrent, de-superheats and
starts to condense. The de-superheating heat and condensation is released to the condensation water which heats
accordingly.
The condensed fluid at saturation temperature passes through the sub cooling section, where it yields heat to further
increase cycle efficiency. The sub cooled fluid flows through the expansion device which, through a pressure drop, initiates
the expansion process by vaporizing a part of the refrigerant liquid.
The result at this point is a mixture of liquid and gas at low pressure and temperature, which is introduced into the
evaporator.
The liquid-vapor refrigerant after being evenly distributed along the tube bundle exchanges heat with the water to be cooled
by reducing the temperature, and it gradually changes state until being fully evaporated.
Reaching the vapor state, it leaves the evaporator to be sucked by compressor again and restart the cycle.
3.3.1
Evaporator
The evaporator is a flooded shell and tube type with water flowing inside the tubes and the gas refrigerant outside. Normall y
it does not require any maintenance and service. Should a tube require replacement, the old tube can be removed and
replaced. The water dome gasket must be replaced after tube cleaning and/or replacement.
3.3.2
Condenser
The condenser is a shell and tube type with water flowing inside the tubes and the refrigerant outside. The condenser tubes
are externally finned and expanded on the tube plate. A sub cooler is built into the condenser on all units. Should a tube
require replacement, the old tube can be removed and replaced. The water dome gasket must be replaced after tube
cleaning and/or replacement.
3.3.3
Expansion valve
The expansion valve is electrically controlled by the electronic controller by means of a specifically designed electronic
board. A special algorithm designed for machines with flooded evaporators, manages the refrigerant flow to the evaporator
according to machine operating parameters. In the event of blackout, the expansion valve automatically closes thanks to an
electric power accumulation system placed inside the electronic control board (supercap)
3.3.4
Compressors
The refrigeration compressor is the single screw type with the rotation shaft directly coupled to the electric motor.
The vapor flows through the electric motor cooling the windings before entering the suction ports. Sensors able to constantly
monitor temperature are located inside the motor windings to fully protect the motor against dangerous overheating. The
thermistor and power terminals are housed within a terminal box placed above the motor housing.
Moving compressor parts that effect the compression consist of three rotating parts, there are no parts in eccentric or
reciprocating movement in the compressor. The essential components are the main rotor and the two side satellites that
perfectly integrate together. The compressor is sealed by a suitably shaped special synthetic material placed between the
main rotor and the satellites. The main shaft on which both the motor and the main rotor are installed is supported by three
ball bearings. This system is both statically and dynamically balanced before assembly. Two large closing flanges are
