12.3. REFRIGERANT PIPING WORK
12.3.1. Piping Materials
It is recommended that you use copper and copper alloy jointless pipes with a maximum oil adherence of 40 mg/10m. Do not use pipes that are crushed, deformed, or discolored (especially the inside surface). If these inferior pipes are used, impurities may clog the 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 are appropriate 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 0.7 mm is also available on the market, but this should never be used.
Table 10 Copper tube thickness (mm)
| Soft pipe |
| Thickness (mm) | ||
Nominal diameter |
| Outside diameter (mm) | R410A |
| (Reference) R22 |
1/4 |
| 6.35 | 0.80 |
| 0.80 |
3/8 |
| 9.52 | 0.80 |
| 0.80 |
1/2 |
| 12.7 | 0.80 |
| 0.80 |
12.3.2. Processing and Connecting Piping Materials
When working with refrigerant piping, the following points must be carefully observed: no moisture od dust must be allowed to enter the piping, and there must be no refrigerant leaks.
1. Procedure and precautions for flaring work
a. Cut the pipe
Use a pipe cutter, and cut slowly so the pipe will not be deformed.
b. Remove burrs and clean shavings from the cut surface If the shape of the pipe end is poor after removing burrs, or if shavings adhere to the flared area, it may lead to refrigerant leaks.
To prevent this, turn the cut surface downward and remove burrs, then clean the surface, carefully.
Fig. 10 Flaring dimensions
c. Insert the flare nut (be sure to use the same nut that is used on the AC unit)
d.Flaring
Check the clamp bar and the cleanliness of the copper pipe.
Be sure to use the clamp bar to do the flaring with accuracy. Use either an R410A flaring tool, or a conventional flaring tool. Flaring tools come in different sizes, so be sure to check the size before using. When using a conventional flaring tool, use the copper pipe gauge for clearance adjustment, etc., to ensure the correct A dimension (see Fig. 10)
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