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(2) Cautions for refrigerant piping work
New refrigerant R32 is adopted for replacement inverter series. Although the refrigerant piping work for R32 is same as for
R22, exclusive tools are necessary so as not to mix with different kind of refrigerant. Furthermore as the working pressure
of R32 is 1.6 times higher than that of R22, their sizes of flared sections and flare nuts are different.
Thickness of pipes
Because the working pressure of R32 is higher compared to R22, be sure to use refrigerant piping with thickness shown
below. (Never use pipes of 0.7 mm or below.)
Diagram below: Piping diameter and thickness
Nominal
Outside
dimensions(inch)
diameter (mm)
1/4
3/8
1/2
5/8
3/4
Dimensions of flare cutting and flare nut
The component molecules in HFC refrigerant are smaller compared to conventional refrigerants. In addition to that, R32
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 R32 has been specified sepa-
rately from the dimensions for other refrigerants as shown below. The dimension B of flare nut for R32 also has partly
been changed to increase strength as shown below. Set copper pipe correctly referring to copper pipe flaring dimensions
for R32 below. For 1/2 and 5/8 inch pipes, the dimension B changes.
Use torque wrench corresponding to each dimension.
Dimension A
Flare cutting dimensions
Nominal
Outside
dimensions(inch)
diameter(mm) R32/R410a
1/4
6.35
3/8
9.52
1/2
12.70
5/8
15.88
3/4
19.05
Tools for R32 (The following table shows whether conventional tools can be used or not.)
Tools and materials
Gauge manifold
Air purge, refrigerant
charge and operation
Charge hose
check
Gas leak detector
Gas leak check
Refrigerant recovery
Refrigerant recovery
equipment
Refrigerant cylinder
Refrigerant charge
Safety charger
Prevent compressor malfunction
when charging refrigerant by
spraying liquid refrigerant
Charge valve
Prevent gas from blowing out
when detaching charge hose
Vacuum pump
Vacuum drying and air
purge
Flare tool
Flaring work of piping
Bender
Bend the pipes
Pipe cutter
Cut the pipes
Welder and nitrogen
Weld the pipes
gas cylinder
Refrigerant charging
Refrigerant charge
scale
Vacuum gauge or
Check the degree of vacuum.
thermistor vacuum
(Vacuum valve prevents back
gauge and vacuum
fl ow of oil and refrigerant to
valve
thermistor vacuum gauge)
Charging cylinder
Refrigerant charge
: Prepare a new tool. (Use the new tool as the tool exclusive for R32.)
: Tools for other refrigerants can be used under certain conditions.
: Tools for other refrigerants can be used.
OBH790
Thickness (mm)
R32/R410a
6.35
0.8
9.52
0.8
12.70
0.8
15.88
1.0
—
19.05
Dimension A (
+0
)
(mm)
-0.4
R22
9.1
9.0
13.2
13.0
16.6
16.2
19.7
19.4
—
23.3
Use
R32 tools
Tool exclusive for R32
Tool exclusive for R32
Tool for HFC refrigerant
Tool exclusive for R32
Tool exclusive for R32
Tool exclusive for R32
Tool exclusive for R32
Tools for other refrigerants
can be used if equipped
with adapter for reverse
fl ow check
Tools for other refrigerants
can be used by adjusting
fl aring dimension
Tools for other refrigerants
can be used
Tools for other refrigerants
can be used
Tools for other refrigerants
can be used
Tools for other refrigerants
can be used
Tools for other refrigerants
can be used
Tool exclusive for R32
R22
0.8
0.8
0.8
1.0
1.0
Flare nut dimensions
Nominal
Outside
dimensions(inch)
diameter(mm)
1/4
6.35
3/8
9.52
1/2
12.70
5/8
15.88
3/4
19.05
Can R22 tools be used?
(Usable if equipped with
adapter for reverse
fl ow)
(Usable by adjusting
fl aring dimension)
10
Dimension B
(mm)
Dimension B
R32/R410a
R22
17.0
17.0
22.0
22.0
26.0
24.0
29.0 *
27.0
—
36.0
Can R407C tools be used? Can R410a tools be used?
(Usable if equipped with
(Usable if equipped with
adapter for reverse
adapter for reverse
fl ow)
fl ow)
(Usable by adjusting
(Usable by adjusting
fl aring dimension)
fl aring dimension)
–
* 36.0mm for
indoor unit
of RP100,
125 and 140
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