9
OCH775
(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.
1
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.)
2
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.
3
Tools for R32 (The following table shows whether conventional tools can be used or not.)
1/4
3/8
1/2
5/8
3/4
6.35
9.52
12.70
15.88
19.05
0.8
0.8
0.8
1.0
—
0.8
0.8
0.8
1.0
1.0
Nominal
dimensions (inch)
Diagram below: Piping diameter and thickness
Outside
diameter (mm)
Thickness (mm)
R32/R410a
R22
1/4
3/8
1/2
5/8
3/4
6.35
9.52
12.70
15.88
19.05
9.1
13.2
16.6
19.7
—
9.0
13.0
16.2
19.4
23.3
Nominal
dimensions (in)
Flare cutting dimensions
Outside
diameter
Dimension A ( )
+0
-0.4
(mm)
(mm) R32/R410a
R22
1/4
3/8
1/2
5/8
3/4
6.35
9.52
12.70
15.88
19.05
17.0
22.0
26.0
29.0
—
17.0
22.0
24.0
27.0
36.0
Nominal
dimensions (in)
Flare nut dimensions
Outside
diameter
Dimension B (mm)
(mm) R32/R410a
R22
Dimension A
Dimension B
Gauge manifold
Charge hose
Gas leak detector
Refrigerant recovery equipment
Refrigerant cylinder
Safety charger
Charge valve
Vacuum pump
Flare tool
Bender
Pipe cutter
Welder and nitrogen gas cylinder
Refrigerant charging scale
Vacuum gauge or thermis-
tor vacuum gauge and
vacuum valve
Charging cylinder
Air purge, refrigerant charge
and operation check
Gas leak check
Refrigerant recovery
Refrigerant charge
Prevent compressor malfunction
when charging refrigerant by
spraying liquid refrigerant
Prevent gas from blowing out
when detaching charge hose
Vacuum drying and air
purge
Flaring work of piping
Bend the pipes
Cut the pipes
Weld the pipes
Refrigerant charge
Check the degree of vacuum. (Vacuum
valve prevents back flow of oil and refri-
gerant to thermistor vacuum gauge)
Refrigerant charge
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 adap-
ter for reverse flow check
Tools for other refrigerants
can be used by adjusting
flaring 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
Tools and materials
Use
R32 tools
(Usable if equipped
with adapter for rever-
se flow)
(Usable by adjusting
flaring dimension)
(Usable if equipped
with adapter for rever-
se flow)
(Usable by adjusting
flaring dimension)
: 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.
Can R22 tools be used? Can R407C tools be used?
(Usable if equipped
with adapter for rever-
se flow)
(Usable by adjusting
flaring dimension)
Can R410a tools be used?
