6
Mareli Systems
Remove refrigerant and vacuum
Maintenance or other operations on the refrigeration circuit should be performed in accordance with normal
procedures. Safety should also be considered and the procedure should be followed:
1. Remove refrigerant;
2. Purify the pipeline with inert gas;
3. Vacuum;
4. Purify the pipeline with inert gas again;
5. Cut and replace the pipe or weld it.
e refrigerant should be recovered into a suitable cylinder. e system should be purged with oxygen-free
nitrogen. is process may need to be repeated several times. Do not use compressed air or oxygen for this
operation.
Procedure before pipe welding:
Procedure of charging refrigerant
As a supplement for the conventional procedures, the following requirements have been added:
1. When using refrigerant charging equipment, avoid mutual contamination between dierent refriger-
ants. e pipeline of refrigerant lling should be as short as possible to reduce the residual amount of
refrigerant;
2. When lling refrigerant, remove all re sources near the unit;
3. Make sure that the refrigerant system is grounded before charging the refrigerant;
4. Aer charging refrigerant, stick label on the system;
5. Avoid excessive charge;
Perform a pressure test with oxygen-free nitrogen before charging refrigerant into the system. Aer charging,
a leak test should be performed before the operation. e leak test should be performed again when leaving
the area.
Scrapping
Before proceeding with this procedure, the technician should be aware of the equipment and all of its char-
acteristics. It is mandatory to recover the refrigerant safe. If it is necessary to re-use the recovered refrigerant,
samples of refrigerant and oil should be analyzed.
1. Before proceeding be aware of the equipment and its operation;
2. Disconnect the power supply;
3. Before proceeding with this procedure make sure that:
If necessary, the equipment of mechanical operation should be convenient to operate the refrigerant storage tank;
All personal protective equipment is available, eective and is used correctly;
e entire recycling process should be done under the guidance of qualied persons; Recycling equipment and
refrigerant storage tanks should meet the corresponding standards.
Maintenance safety
Warning
1. For repairs or scrapping, please contact the nearest or authorized service centre.
2. Repairs performed by unqualied personnel may be dangerous.
3. When charging the heat pump with R32 refrigerant and maintaining it, please strictly observe the manu-
facturer's requirements. is chapter mainly focuses on the special maintenance requirements of R32 re-
frigeration appliances. Please refer to the aer-sales service manual for detailed maintenance operations.
In the purging process, the system is lled with oxygen-free nitrogen to reach the working pressure under the
vacuum state of the system, and then the oxygen-free nitrogen is discharged, and nally the system is evacu-
ated. Repeat this process until all refrigerant in the system is removed. Aer lling the oxygen-free nitrogen
for the last time, exhaust the gas to atmospheric pressure, and then the system is ready for welding. e above
operations are necessary for pipeline welding operations.
Ensure that there is no ignition source near the outlet of the vacuum pump. Ensure good ventilation of the area.
