Mitsubishi Electric MXZ-2C20NA2, Service Manual

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11
2-3. Cautions for refrigerant piping work
Refrigerant R410A is adopted for replacement inverter series. Although the refrigerant piping work for R410A is the same as for
R22, exclusive tools are necessary so as not to mix with different kind of refrigerant. Furthermore as the working pressure of
R410A is 1.6 times higher than that of R22, their sizes of flared sections and flare nuts are different.
Thickness of pipes
Since the working pressure of R410A is higher compared to R22, be sure to use refrigerant piping with thickness shown below.
(Never use pipes of 7/256 in [0.7 mm] or below.)
Diagram below: Piping diameter and thickness
Nominal
dimensions (inch)
Outside
diameter (mm)
Thickness: in [mm]
R410A R22
1/4 6.35 1/32 [0.8] 1/32 [0.8]
3/8 9.52 1/32 [0.8] 1/32 [0.8]
1/2 12.70 1/32 [0.8] 1/32 [0.8]
5/8 15.88 5/128 [1.0] 5/128 [1.0]
3/4 19.05 — 5/128 [1.0]
Dimensions of flare cutting and flare nut
The component molecules in HFC refrigerant are smaller compared to conventional refrigerants. In addition to that, R410A is
a refrigerant, which has higher risk of leakage because its working pressure is higher than that of other refrigerants. Therefore,
to enhance airtightness and strength, flare cutting dimension of copper pipe for R410A has been specified separately from the
dimensions for other refrigerants as shown below. The dimension B of flare nut for R410A also has partly been changed to
increase strength as shown below. Set copper pipe correctly referring to copper pipe flaring dimensions for R410A below. For
1/2 and 5/8 inch pipes, the dimension B changes.
Use torque wrench corresponding to each dimension.
Dimension A
Dimension B
Flare cutting dimensions Unit: in [mm]
Nominal
dimensions (in)
Outside
diameter (mm)
Dimension A (
+0
-0.4
)
R410A R22
1/4 6.35 11/32-23/64 [9.1] 9.0
3/8 9.52 1/2-33/64 [13.2] 13.0
1/2 12.70 41/64-21/32 [16.6] 16.2
5/8 15.88 49/64-25/32 [19.7] 19.4
3/4 19.05 — 23.3
Flare nut dimensions Unit: in [mm]
Nominal
dimensions (in)
Outside
diameter (mm)
Dimension B
R410A R22
1/4 6.35 43/64 [17.0] 17.0
3/8 9.52 7/8 [22.0] 22.0
1/2 12.70 1-3/64 [26.0] 24.0
5/8 15.88 1-9/64 [29.0] 27.0
3/4 19.05 — 36.0
OBH702N