9411.3. Refrigerant piping work11.3.1. Piping materialsIt is recommended that you use copper and copper alloy jointless pipes with a maximum oil adherence of 40 mg/10m. Do not usepipes that are crushed, deformed, or discolored (especially the inside surface). If these inferior pipes are used, impurities may clogthe expansion valves or capillaries.Because the pressure of ACs using R410A is higher than those using R22, it is essential that you select materials that areappropriate for these standards.The thickness of the copper tubing used for R410A is shown in Table 10. Please be aware that tubing with a thickness of only 0.7mm is also available on the market, but this should never be used.Table 10 Copper tube thickness (mm)11.3.2. Processing and connecting piping materialsWhen working with refrigerant piping, the following points mustbe carefully observed: no moisture or dust must be allowed toenter the piping, and there must be no refrigerant leaks.1. Procedure and precautions for flaring worka. Cut the pipeUse a pipe cutter, and cut slowly so the pipe will notbe deformed.b. Remove burrs and clean shavings from the cutsurfaceIf the shape of the pipe end is poor after removingburrs, or if shavings adhere to the flared area, it maylead to refrigerant leaks.To prevent this, turn the cut surface downward andremove burrs, then clean the surface, carefully.c. Insert the flare nut (be sure to use the same nut that isused on the AC unit)d. FlaringCheck the clamp bar and the cleanliness of thecopper pipe.Be sure to use the clamp bar to do the flaring withaccuracy. Use either an R410A flaring tool, or aconventional flaring tool. Flaring tools come indifferent sizes, so be sure to check the size beforeusing. When using a conventional flaring tool, use thecopper pipe gauge for clearance adjustment, etc., toensure the correct A dimension (see Fig. 10)Fig. 10 Flaring dimensionsFig. 11 Relation between the flare nut structure and flaring tool endSoft pipe Thickness (mm)Nominal diameter Outside diameter (mm) R410A (Reference) R221/4 6.35 0.80 0.803/8 9.52 0.80 0.801/2 12.7 0.80 0.805/8 15.88 1.00 1.00
