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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 clearing;
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 plugged;
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°C 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.
Scrapping and Recovery
Scrapping
Before scrapping, the technician shall be completely familiar with the equipment and all its features. The safe
recovery of refrigerant is recommended. In case the refrigerant recovered needs to be reused, before which the
sample of refrigerant and oil shall be analyzed. The power supply required shall be guaranteed before tests.
(1) The equipment and operation shall be well known;
(2) Power supply shall be switched off;
(3) The followings shall be guaranteed before scrapping:
The mechanical equipment shall be convenient for operation on the cylinder of refrigerant (if necessary);
All personal protective equipment is available and being used correctly;
The whole course of recovery shall be guided by qualified personnel;
The recovery equipment and cylinders shall be in line with corresponding standards.
(4) The refrigeration system shall be vacuumized if possible;
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