5
OCH754A
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 time 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 7/256 inch [0.7mm] or below.)
Nominal
dimensions (in)
Outside
diameter (mm)
Thickness: in (mm)
R410A
R22
1/4
6.35
1/32 (0.8)
1/32 (0.8)
3/8
9.52
1/32 (0.8)
1/32 (0.8)
1/2
12.70
1/32 (0.8)
1/32 (0.8)
5/8
15.88
5/128 (1.0)
5/128 (1.0)
3/4
19.05
—
5/128 (1.0)
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 air tightness and intensity, 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
Dimension B
3
Tools for R410A (The following table shows whether conventional tools can be used or not.)
Tools and materials
Use
R410A tools
Can R22 tools be used?
Gauge manifold
Air purge, refrigerant charge and
operation check
Tool exclusive for R410A
Charge hose
Tool exclusive for R410A
Gas leak detector
Gas leak check
Tool for HFC refrigerant
Refrigerant recovery equipment
Refrigerant recovery
Tool exclusive for R410A
Refrigerant cylinder
Refrigerant charge
Tool exclusive for R410A
Applied oil
Apply to flared section
Ester oil and alkylbenzene oil
(minimum amount)
Safety charger
Prevent compressor malfunction when
charging refrigerant by spraying liquid
refrigerant
Tool exclusive for R410A
Charge valve
Prevent gas from blowing out when
detaching charge hose
Tool exclusive for R410A
Vacuum pump
Vacuum drying and air purge
Tools for other refrigerants can be
used if equipped with adopter for
reverse flow check
(Usable if equipped with adopter for
reverse flow)
Flare tool
Flaring work of piping
Tools for other refrigerants can be
used by adjusting flaring dimension
(Usable by adjusting flaring
dimension)
Bender
Bend the pipes
Tools for other refrigerants can be used
Pipe cutter
Cut the pipes
Tools for other refrigerants can be used
Welder and nitrogen gas cylinder
Weld the pipes
Tools for other refrigerants can be used
Refrigerant charging scale
Recover refrigerant
Tools for other refrigerants can be used
Vacuum gauge or thermistor vacuum
gauge and vacuum valve
Check the degree of vacuum. (Vacuum
valve prevents back flow of oil and
refrigerant to thermistor vacuum gauge)
Tools can be used for other
refrigerants.
Charging cylinder
Recover refrigerant
Tool exclusive for R410A
: 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.
Diagram below: Piping diameter and thickness
Nominal
dimensions (in)
Outside
diameter (mm)
Thickness: in (mm)
R410A
R22
1/4
6.35
1/32 (0.8)
1/32 (0.8)
3/8
9.52
1/32 (0.8)
1/32 (0.8)
1/2
12.70
1/32 (0.8)
1/32 (0.8)
5/8
15.88
5/128 (1.0)
5/128 (1.0)
3/4
19.05
—
5/128 (1.0)
Flare nut dimensions
Nominal
dimensions (in)
Outside
diameter (mm)
Dimension B: in (mm)
R410A
R22
1/4
6.35
43/64 (17.0)
17.0
3/8
9.52
7/8 (22.0)
22.0
1/2
12.70
1-3/64 (26.0)
24.0
5/8
15.88
1-9/64 (29.0)
27.0
3/4
19.05
—
36.0