Cautions For Refrigerant Piping Work; Thickness Of Pipes; Dimensions Of Flare Cutting And Flare Nut; Tools For R410A - Mitsubishi Electric PUZ-A18NHA4 Service Manual

2-3. 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 [7/256 inch] or below.)
Diagram below: Piping diameter and thickness
Nominal
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,
R410A is a refrigerant, which has higher risk of leakage because of its working pressure is higher than that of other
refrigerants. Therefore, to enhance air tightness and intensity, 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 intensity as shown below. Set copper pipe correctly referring to cop-
per pipe flaring dimensions for R410A below. For 1/2 and 5/8 inch, the dimension B changes.
Use torque wrench corresponding to each dimension.
Dimension A
Flare cutting dimensions
Nominal
dimensions[inch]
1/4
3/8
1/2
5/8
3/4
3 Tools for R410A (The following table shows whether conventional tools can be used or not.)
Tools and materials
Gauge manifold
Charge hose
Gas leak detector
Refrigerant recovery equipment
Refrigerant cylinder
Applied oil
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
: 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.
Thickness : mm [inch]
Outside
diameter (mm)
R410A
6.35 0.8 [1/32]
9.52 0.8 [1/32]
12.70 0.8 [1/32]
15.88 1.0 [5/128]
—
19.05
Dimension A (
Outside
diameter R410A
6.35 9.1 [11/32-23/64]
9.52 13.2 [1/2-33/64]
12.70 16.6 [41/64-21/32]
15.88 19.7 [49/64-25/32]
19.05 —
Use
Air purge, refrigerant charge
and operation check
Gas leak check
Collection of refrigerant
Refrigerant charge
Apply to flared section
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
R22
0.8 [1/32]
0.8 [1/32]
0.8 [1/32]
1.0 [5/128]
1.0 [5/128]
Unit : mm [inch] Flare nut dimensions
)
+0
Nominal
-0.4
R22 dimensions[inch]
9.0 1/4
13.0 3/8
16.2 1/2
19.4 5/8
23.3 3/4
R410A tools Can R22 tools be used?
Tool exclusive for R410A
Tool exclusive for R410A
Tool for HFC refrigerant
Tool exclusive for R410A
Tool exclusive for R410A
Ester oil, ether oil and
alkylbenzene oil(minimum amount)
Tool exclusive for R410A
Tool exclusive for R410A
Tools for other refrigerants can
be used if equipped with adop-
ter for reverse flow check
Tools for other refrigerants
can be used by adjusting
flaring dimension
Tools can be used for other refrigerants
Tools can be used for other refrigerants
Tools can be used for other refrigerants
Tools can be used for other refrigerants
Tools can be used for other
refrigerants
Tool exclusive for R410A
5
Dimension B
Dimension B
Outside
diameter R410A
6.35 17.0 [43/64]
9.52 22.0 [7/8]
12.70 26.0 [1-3/64]
15.88 29.0 [1-9/64]
19.05 —
(Usable if equipped
with adopter for rever-
se flow)
(Usable by adjusting
flaring dimension)
Unit : mm [inch]
R22
17.0
22.0
24.0
27.0
36.0