Haier 1U71S2SG1FA Service Manual page 176

Maintenance of Intrinsically Safe Elements
• The intrinsically safe element refers to the components working continuously inside flammable gas without any
risks.
• Before any maintenance, leak detection and inspection on earthing reliability of the air conditioner must be carried
out, to ensure no leakage and reliable earthing.
• In case the allowable voltage and current limit may be surpassed during the service of the air conditioner, any
inductance or capacitance cannot be added in the circuit.
• Only the elements appointed by the air conditioner manufacturer can be used as the parts and components
replaced, or otherwise a fire or explosion may be triggered in case of refrigerant leakage.
• For the maintenance not involved in system pipelines, the system pipelines shall be well protected, to ensure that
no leakage will be caused due to maintenance.
• After maintenance and before test run, the air conditioner must be subject to leak detection and inspection on
earthing reliability with leak detection equipment or leak detecting solution. It shall be guaranteed that the startup
inspection is carried out without leakage and under reliable earthing.
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.
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