8413.7 Repairing of refrigerant cycle / Brazing point13.7.1 Preparation for repairing of refrigerant cycle / brazingBrazing which is a technique needed for repairing refrigerant cycle requires advanced technique and experience, andthis brazing procedure can only be performed by the workers who completed “Gas Welding Skill Training” regulatedby the Occupational Safety and Health Act, and went through the training programs of refrigerant operations.Dismantling and re-connecting (assembling) refrigerant system requires working space, and the space has to ensuregood air flow and fire prevention (water bucket and fire extinguisher). Moreover, the worker has to ensure thewearing of goggles, grabs, safety shoes, and long sleeve shirts, and be aware of work safety and attempt to preventsecondary defect (quality assurance of products). For brazing the indoor / outdoor unit structural components (heatexchangers, compressors, expansion valves, four-way valve blocks), after the recovery of all refrigerant, confirm thatno refrigerant remains in the system, and fully open the 2-way and 3-way valves. When the brazing is conductedoutside, check and make sure no refrigerant is contained in the air (be careful with vaporized refrigerant).Furthermore, protect the compressor terminal with metal plates, and heat but use wet clothes to cool down (releasingthe heat) the expansion valves, and four way valves (prevent destruction of parts). In brazing, it is important to pourthe brazing material without melting the base metal based on capillary action principle. In case of holes and oxidizingcaused by overheating, do not perform re-brazing or alteration but replace the parts.13.7.2 Adjustment of vacuum pump pressure1. Cylinder with adjustment handle1. Check and confirm the adjustment handle of the 1 st pressure adjuster is loosen (anticlockwise). If cylindervalve is opened when the 1 st gauge pressure adjust handle is closed, the 2 nd gauge might get broken.2. Open the cylinder valve, and check the remaining amount with the first t side pressure gauge.3. Check the pressure of 2 nd gauge and turn the adjustment handle to clock-wise direction to adjust thepressure.◎ Oxygen 2 nd side gauge pressure・・・・・・・・・・0.5 MPa (5.0 kgf / cm2)◎ Propane 2nd side gauge pressure・・・・・・・0.05 MPa (0.5 kgf / cm2)The primary gauge(High pressure)The secondary gauge(Low pressure) The secondary gauge(Low pressure)AdjustmenthandleAdjustmenthandleOxygen regulator Propane regulatorMain valveMain valve