Mitsubishi Heavy Industries SRK20ZIX-S Service Manual page 96

Nominal
diameter
1/4
3/8
1/2
(2) Flare connecting procedures and precautions
a) Make sure that the flare and union portions do not have any scar or dust, etc.
b) Correctly align the processed flare surface with the union axis.
c) Tighten the flare with designated torque by means of a torque wrench. The tightening torque for R410A is same as that for
conventional R22. Incidentally, when the torque is weak, the gas leakage may occur. When it is strong, the flare nut may
crack and may be made nonremovable. When choosing the tightening torque, comply with values designated by manufac-
turers. Table 9 shows reference values.
Note : When applying oil to the flare surface, be sure to use oil designated by the manufacturer. If any other oil is used, the lubricating oils may deteriorate and
cause the compressor to burn out.
4.2.3 Storage of piping materials
(1) Types and storage of piping materials
Refrigerant piping materials for air conditioners are broadly classified into the following types.
Refrigerant piping
materials
As R410A features pressure about 1.6 times higher than R22, it is necessary to use a copper pipe which has a thickness stated
in Table 3 (see page 92) and which contains less contaminants. It is necessary to carefully treat/store copper pipes so that they
are not collapsed, deformed or damaged. Due care must also be exercised so that foreign matters such as dust and water do not
enter the pipe interior.
A piping set's open end is sealed with a cap, etc. When storing it, make sure that it is sealed securely. When storing a cladded
copper pipe or bare copper pipe, securely seal the opening with pinching, taping, etc.
Table 8. Flare and flare nut dimensions for R22
Outer diameter Thickness
(mm) (mm)
6.35 0.8
9.52 0.8
12.7 0.8
Table 9. Tightening torque of flare for R410A [Reference values]
Nominal Outer diameter
diameter (mm)
1/4 6.35
3/8 9.52
1/2 12.7
with heat
insulation
without heat
insulation
(bare copper pipe)
Dimension (mm)
A B
9.0 9.2
13.0 13.5
16.2 16.0
Tightening torque
N·m (kgf·cm)
14~18 (140~180)
34~42 (340~420)
49~61 (490~610)
General name
with flare processing : (a) Piping set
without flare processing : (b) Copper pipe with insulation
without flare processing : (c) Bare copper pipe
95
- -
C D
6.5 13
9.7 20
12.9 20
Tightening torque of torque
wrenches available on the
market N·m (kgf·cm)
16 (160), 18 (180)
42 (420)
55 (550)
[unit: mm]
Flare nut width
17
22
24