2. Pipe design
2-1. Important items when using refrigerant (R32)
• Refrigerant piping material and wall thickness
It is necessary to use seamless copper tubes for refrigerant use. Thickness of tubes are shown in
table below.
Nominal diameter in 1/4 3/8 1/2 5/8 3/4 7/8 1-1/8
Outside diameter mm 6.35 9.52 12.70 15.88 19.05 22.22 28.58
Material
JIS H3300 C1220T-O or equivalent*
1
JIS H3300 C1220T-H
or equivalent*
2
Wall thickness*
3
mm 0.8 1.0 1.2 1.0
*1: Allowable tensile stress ≥ 33 N/mm
2
*2: Allowable tensile stress ≥ 61 N/mm
2
*3: Endurance pressure of the pipes: 4.2 MPa
Select the pipe size in accordance with local rules.
• Lubricant
Refrigerant R32
Lubricant Synthetic oil
• Tools
R32 work requires a number of special tools. Since the tools (with * symbol) for R22 work cannot
be used for R32, prepare them beforehand.
Tool name Process and application
Pipe cutter Pipe cutting
Refrigerant piping work
Flaring tool* Pipe flaring work
Torque wrench* Flare nut connection
Expander Expansion at pipe connection
Pipe bender Pipe bending work
Nitrogen gas Pipe interior oxidation prevention
Air tightness test
Welder Pipe brazing
Gauge manifold* Vacuum evacuation and
refrigerant charging operation
check
Air tightness test ~ Refrigerant
additional charging
Charging hose*
Vacuum pump (with adapter)* Vacuum drying
Electronic scale for refrigerant
charging
Refrigerant additional charging
Gas leak tester* Gas leakage test
*: For details, refer to the service manual.
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2-1. Important items when using refrigerant (R32) 2. Pipe design
SYSTEM
DESIGN
SYSTEM
DESIGN
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