Cautions For Refrigerant Piping Work; Thickness Of Pipes; Dimensions Of Flare Cutting And Flare Nut; Flare Cutting Dimensions - Mitsubishi Electric PUZ-ZM35VKA Service Manual

(2) Cautions for refrigerant piping work

New refrigerant R410A is adopted for replacement inverter series. Although the refrigerant piping work for R410A 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 R410A 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 R410A 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
dimensions(inch) diameter (mm)
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,
R410A is a refrigerant, which has higher risk of leakage because its working pressure is higher than that of other refriger-
ants. Therefore, to enhance airtightness and strength, flare cutting dimension of copper pipe for R410A has been speci-
fied 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

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
3 Tools for R410A (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 flow 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 R410A.)
: Tools for other refrigerants can be used under certain conditions.
: Tools for other refrigerants can be used.
OCH653
Thickness (mm)
Outside
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 R410A tools
Tool exclusive for R410A
Tool exclusive for R410A
Tool for HFC refrigerant
Tool exclusive for R410A
Tool exclusive for R410A
Tool exclusive for R410A
Tool exclusive for R410A
Tools for other refrigerants
can be used if equipped
with adapter 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 R410A
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
flow)
(Usable by adjusting
flaring dimension)
9
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
flow) flow)
(Usable by adjusting (Usable by adjusting
flaring dimension) flaring dimension)
–
* 36.0mm for
indoor unit
of RP100,
125 and 140