Mitsubishi Electric PUZ-M200YKA Service Manual page 9

(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.)
Diagram below: Piping diameter and thickness
Nominal Outside
diameter (mm)
dimensions (inch)
1/4
3/8
1/2
5/8
3/4
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.
Dimension A
Flare cutting dimensions
Nominal Outside
dimensions (in) diameter
1/4 6.35
9.52
3/8
1/2 12.70
5/8 15.88
3/4 19.05
3 Tools for R32 (The following table shows whether conventional tools can be used or not.)
Tools and materials Use
Gauge manifold Air purge, refrigerant charge
and operation check
Charge hose
Gas leak detector Gas leak check
Refrigerant recovery equipment Refrigerant recovery
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 gas cylinder Weld the pipes
Refrigerant charge
Refrigerant charging scale
Vacuum gauge or thermis- Check the degree of vacuum. (Vacuum
valve prevents back flow of oil and refri-
tor vacuum gauge and
gerant to thermistor vacuum gauge)
vacuum valve
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.
OCH737
Thickness (mm)
R32/R410a
6.35 0.8
9.52 0.8
12.70 0.8
15.88 1.0
—
19.05
Dimension A ( )
(mm)
+0
-0.4
(mm) R32/R410a
R22
9.1 9.0
13.2 13.0
16.6 16.2
19.7 19.4
—
23.3
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 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
R22
0.8
0.8
0.8
1.0
1.0
Flare nut dimensions
Nominal Outside
(mm) R32/R410a
dimensions (in) diameter
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? Can R407C tools be used?
(Usable if equipped
with adapter for rever-
se flow)
(Usable by adjusting
flaring dimension)
9
Dimension B
Dimension B (mm)
R22
17.0 17.0
22.0 22.0
26.0 24.0
29.0 27.0
—
36.0
Can R410a tools be used?
(Usable if equipped (Usable if equipped
with adapter for rever- with adapter for rever-
se flow) se flow)
(Usable by adjusting (Usable by adjusting
flaring dimension) flaring dimension)