D
–EIMWC00408-16EN - 50/60
Refrigerant charge
ATTENTION
The units have been designed to operate with R134a refrigerant. DO NOT USE refrigerants other than R134a.
WARNING
The addition or removal of refrigerant gas must be carried out in compliance with the laws and regulations in force.
ATTENTION
When refrigerant gas is added to or removed from the system, ensure proper water flow through the evaporator for
the entire charge/discharge time. Interrupting the water flow during this procedure would cause the evaporator to
freeze with consequent breakage of its internal piping.
Damage caused by freezing makes the warranty void.
WARNING
Removal of the refrigerant and replenishing operations must be performed by technicians who are qualified to use the
appropriate materials for this unit. Unsuitable maintenance can result in uncontrolled losses in pressure and fluid. Do
not disperse the refrigerant and lubricating oil in the environment. Always be equipped with a suitable recovery
system.
The units ship with a full refrigerant charge, but in some cases it might be necessary to replenish the machine in the field.
ATTENTION
Always verify the causes of a loss of refrigerant. Repair the system if necessary then recharge it.
The machine can be replenished under any stable load condition (preferably between 70 and 100%) and under any
ambient temperature condition (preferably above 20°C). The machine should be kept running for at least 5 minutes to
allow the condensation pressure to stabilise.
The subcooling value is about 3-4°C.
Once the subcooling section has been completely filled, additional refrigerant will not increase system efficiency.
However, a small additional quantity of refrigerant (1
2 kg) makes the system slightly less sensitive.
N.B.
: Subcooling varies and requires a few minutes to re-stabilise. However, subcooling should not come below 2°C
under any condition. Also, the subcooling value can change slightly as the water temperature and the suction
superheating vary. As the suction superheating value decreases, there is a corresponding decrease in subcooling.
One of the two following scenarios can arise in a machine without refrigerant:
1.
If the refrigerant level is slightly low, flow of bubbles can be seen through the liquid sight glass. Replenish
the circuit as described in the replenishment procedure.
2.
If the gas level in the machine is moderately low, the corresponding circuit could have some low-pressure
stops. Replenish the corresponding circuit as described in the replenishment procedure.
Refrigerant filling procedure
1)
If the machine has lost refrigerant, it is necessary to first establish the causes before carrying out any
replenishment operation. The leak must be found and repaired. Oil stains are a good indicator, as they can
appear in the vicinity of a leak. However, this is not necessarily always a good search criterion. Searching
with soap and water can be a good method for medium to large leaks, while an electronic leak detector is
required to find small leaks.
2)
Add refrigerant to the system through the service valve on the suction pipe or through the Schrader valve
located on the evaporator inlet pipe.
3)
The refrigerant can be added under any load condition between 25 and 100% of the system capacity.
Suction superheating must be beteen 4 and 6°C.
4)
Add enough refrigerant to fill the liquid sight glass entirely, so that no flow of bubbles can be seen anymore.
Add an extra 2
3 kg of refrigerant as a reserve, to fill the subcooler if the compressor is operating at 50
–
100% load.
5)
Check the subcooling value by reading the liquid pressure and the liquid temperature near the expansion
valve. The subcooling value must be between 3 and 5°C. The subcooling value will be lower at 75
100%
load and higher at 50% load.
6)
Overcharging the system will cause a rise in the compressor’s discharge pressure.
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