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12.3. Refrigerant Piping Work
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.
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)
Fig. 10 Flaring dimensions
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
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