Haier HU062WAMNA Service Manual page 73

Removal and Vacuumizing
• The maintenance or other operations of the refrigeration circuit shall be made as per conventional procedures.
Moreover, the flammability of refrigerant shall also be mainly considered. The following procedures shall be
followed:
• Refrigerant cleaning;
• Pipeline purification with inert gas;
• Vacuumizing;
• Pipeline purification again with inert gas;
• Pipeline cutting or welding. The refrigerant shall be recovered to a proper cylinder. The system shall be purged
with OFN, to ensure safety. The step above may need to be repeated for several times. Compressed air or
oxygen cannot be used for purging.
In the course of purging, OFN shall be charged inside the refrigeration system under vacuum state, to reach
the operating pressure. Afterwards, the OFN shall be discharged to the atmosphere. Finally, the system shall
be vacuumized. The step above shall be repeated until all the refrigerants in the system are cleared. The OFN
charged for the last time shall be discharged to the atmosphere. Afterwards, the system can be welded. The
operation above is necessary in case of pipeline welding.
It shall be guaranteed that no alight fire source is around the outlet of the vacuum pump and the ventilation is
favorable.
Welding
• Favorable ventilation must be guaranteed in the maintenance area. After the maintenance machine is subject to
the vacuumizing above, the system refrigerant can be discharged on the outdoor unit side.
• Before the outdoor unit is welded, it must be guaranteed that no refrigerant is inside the outdoor unit and the
system refrigerant has been discharged and cleared.
• The refrigeration pipelines cannot be cut with a welding gun under any circumstance. The refrigeration pipelines
must be disassembled with a pipe cutter, and the disassembly must be carried out around a ventilation opening.
Refrigerant Charging Procedures
The following requirements are added as the supplementation of conventional procedures:
• During the use of refrigerant charging tools, cross contamination of different refrigerants shall be avoided. The
total length (including the refrigerant pipelines) shall be shortened as much as possible, to reduce the residual of
refrigerant inside;
• The cylinders of refrigerant shall be kept upright;
• Before refrigerant charging, the refrigeration system shall be earthed;
• A label must be pasted on the refrigeration system after refrigerant charging;
• Excessive charging is not allowed; the refrigerant shall be charged slowly;
• In case system leakage is identified, refrigerant charging is not allowed unless the leak point is repaired;
• During refrigerant charging, the charging amount shall be measured with an electronic scale or a spring scale.
The connecting hose between the refrigerant cylinder and the charging equipment shall be relaxed appropriately,
to avoid impact on the measuring accuracy due to stress.
Requirements on storage site of refrigerant
• The cylinder of refrigerant shall be placed in a -10~50 environment with favorable ventilation, and warning
labels shall be pasted;
• The maintenance tool in contact with the refrigerant shall be stored and used separately, and the maintenance
tool of different refrigerants cannot be mixed.
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