Mitsubishi Electric PUZ-A12NKA7 Service Manual page 5

2-4. 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
Since the working pressure of R410A is higher compared to R22, be sure to use refrigerant piping with thickness
shown below. (Never use pipes of 7/256 inch [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 refrig-
erants. Therefore, to enhance air tightness and strength, 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 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)
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
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.
OCH636A
Thickness : inch [mm]
Outside
R410A
6.35 1/32 [0.8]
9.52 1/32 [0.8]
12.70 1/32 [0.8]
15.88 5/128 [1.0]
—
19.05
Dimension A (
R410A (inch [mm]) R22 (mm)
11/32-23/64 [ 9.1]
1/2-33/64 [13.2]
41/64-21/32 [16.6]
49/64-25/32 [19.7]
—
Use R410A tools
Air purge, refrigerant charge Tool exclusive for R410A
Tool exclusive for R410A
and operation check
Tool for HFC refrigerant
Gas leak check
Collection of refrigerant Tool exclusive for R410A
Refrigerant charge
Tool exclusive for R410A
Apply to flared section Ester oil, ether oil and
alkylbenzene oil(minimum amount)
Tool exclusive for R410A
Prevent compressor malfunction
when charging refrigerant by
spraying liquid refrigerant
Tool exclusive for R410A
Prevent gas from blowing out
when detaching charge hose
Tools for other refrigerants can
Vacuum drying and air
be used if equipped with adop-
purge
ter for reverse flow check
Tools for other refrigerants
Flaring work of piping
can be used by adjusting
flaring dimension
Bend the pipes Tools can be used for other refrigerants
Cut the pipes Tools can be used for other refrigerants
Weld the pipes Tools can be used for other refrigerants
Refrigerant charge Tools can be used for other refrigerants
Check the degree of vacuum. (Vacuum Tools can be used for other
valve prevents back flow of oil and refri-
refrigerants
gerant to thermistor vacuum gauge)
Refrigerant charge Tool exclusive for R410A
R22
1/32 [0.8]
1/32 [0.8]
1/32 [0.8]
5/128 [1.0]
5/128 [1.0]
Flare nut dimensions
)
+0 Nominal
-0.4
dimensions (inch) diameter (mm)
1/4
9.0
3/8
13.0
1/2
16.2
5/8
19.4
3/4
23.3
Can R22 tools be used?
(Usable if equipped
with adopter for rever-
se flow)
(Usable by adjusting
flaring dimension)
5
Dimension B
Outside Dimension B
(inch [mm])
R410A R22
6.35 43/64 [17.0]
9.52 7/8 [22.0]
12.70 1-3/64 [26.0]
15.88 1-9/64 [29.0]
—
19.05
(mm)
17.0
22.0
24.0
27.0
36.0