Installing The Refrigerant Piping; Precautions For Devices That Use R410A Refrigerant - Mitsubishi Electric Mr.SLIM PUZ-A NHA Série Manuel D'installation

4. Installing the refrigerant piping

A
45°±2°
A Flare cutting dimensions
B Flare nut tightening torque
Fig. 4-1
A (Fig. 4-1)
Flare dimensions
Copper pipe O.D.
øA dimensions
(mm) (inch) (mm)
ø6.35 1/4" 8.7 - 9.1
ø9.52 3/8" 12.8 - 13.2
ø12.7 1/2" 16.2 - 16.6 41/64 - 21/32
ø15.88 5/8" 19.3 - 19.7 49/64 - 25/32
B (Fig. 4-1)
Copper pipe O.D. Flare nut O.D.
(mm) (inch) (mm)
ø6.35 1/4" 17
ø9.52 3/8" 22
ø12.7 1/2" 26
ø15.88 5/8" 29
I A12, A18
D
D
A Front piping cover
B Piping cover
C Stop valve
D Service panel
E Band radius : 100 mm, 3-15/16 inch-150 mm, 5-27/32 inch
Fig. 4-3
(inch)
B
C
D
(inch)
11/32 - 23/64
1/2 - 33/64
Tightening torque
(inch) (N·m) (ft·lbs)
43/64 14 - 18 10 - 13
7/8 34 - 42 25 - 30
1 - 3/64 49 - 61 35 - 44
1 - 9/64 68 - 82 49 - 59
I A24-A42
C
B
A E

4.1. Precautions for devices that use R410A refrigerant

• Refer to page 3 for precautions not included below on using air conditioners
with R410A refrigerant.
• Use ester oil, ether oil, alkylbenzene oil (small amount) as the refrigeration oil
applied to the flared sections.
• Use C1220 copper phosphorus, for copper and copper alloy seamless pipes,
to connect the refrigerant pipes. Use refrigerant pipes with the thicknesses
specified in the table to the below. Make sure the insides of the pipes are
clean and do not contain any harmful contaminants such as sulfuric com-
pounds, oxidants, debris, or dust.
Warning:
When installing or moving the air conditioner, use only the specified refriger-
ant (R410A) to charge the refrigerant lines. Do not mix it with any other refriger-
ant and do not allow air to remain in the lines. Air enclosed in the lines can
cause pressure peaks resulting in a rupture and other hazards.
A12, A18
ø6.35 mm, 1/4inch
Liquid pipe
thickness 0.8 mm, 1/32 inch
ø12.7 mm, 1/2 inch
Gas pipe
thickness 0.8 mm, 1/32 inch
• Do not use pipes thinner than those specified above.
4.2. Connecting pipes (Fig. 4-1)
• When commercially available copper pipes are used, wrap liquid and gas pipes
with commercially available insulation materials (heat-resistant to 100 °C, 212 °F or
more, thickness of 12 mm, 1/2 inch or more).
• The indoor parts of the drain pipe should be wrapped with polyethylene foam insu-
lation materials (specific gravity of 0.03, thickness of 9 mm, 23/64 inch or more).
• Apply thin layer of refrigerant oil to pipe and joint seating surface before tightening
flare nut. A
• Use two wrenches to tighten piping connections. B
• Use leak detector or soapy water to check for gas leaks after connections are com-
pleted.
• Apply refrigerating machine oil over the entire flare seat surface. C
• Use the flare nuts for the following pipe size. D
Gas side Pipe size (mm, inch)
Liquid side Pipe size (mm, inch)
*1: The flare nut is attached to its pipe.
*2: The flare nut is in the outdoor unit accessory.
Do not use the flare nut attached. If it is used, a gas leakage or even a pipe
extraction may occur.
• When bending the pipes, be careful not to break them. Bend radii of 100 mm,
3-15/16 inch to 150 mm, 5-27/32 inch are sufficient.
• Make sure the pipes do not contact the compressor. Abnormal noise or vibration
may result.
1 Pipes must be connected starting from the indoor unit.
Flare nuts must be tightened with a torque wrench.
2 Flare the liquid pipes and gas pipes and apply a thin layer of refrigeration oil
(Applied on site).
4.3. Refrigerant piping (Fig. 4-3)
I For A12, A18
Remove the service panel D (one screw).
I For A24-A42
Remove the service panel D (three screws) and the front piping cover A (two screws)
and rear piping cover B (two screws).
1 Perform refrigerant piping connections for the indoor/outdoor unit when the out-
door unit's stop valve is completely closed.
2 Vacuum-purge air from the indoor unit and the connection piping.
3 After connecting the refrigerant pipes, check the connected pipes and the indoor
unit for gas leaks. (Refer to 4.4 Refrigerant pipe airtight testing method)
4 Vacuumize the refrigerant lines through the service port of the liquid stop valve
and then open the stop valves completely (for both the liquid and gas stop valves).
This will completely connect the refrigerant lines of the indoor and outdoor units.
• If the stop valves are left closed and the unit is operated, the compressor and
control valves will be damaged.
• Use a leak detector or soapy water to check for gas leaks at the pipe connec-
tion sections of the outdoor unit.
• Do not use the refrigerant from the unit to purge air from the refrigerant lines.
• After the valve work is completed, tighten the valve caps to the correct torque:
20 to 25 N·m, 14 to 18 ft·lbs (200 to 250 kgf·cm).
Failure to replace and tighten the caps may result in refrigerant leakage. In
addition, do not damage the insides of the valve caps as they act as a seal to
prevent refrigerant leakage.
5 Use sealant to seal the ends of the thermal insulation around the pipe connection
sections to prevent water from entering the thermal insulation.
A24-A42
ø9.52 mm, 3/8 inch
thickness 0.8 mm, 1/32 inch
ø15.88 mm, 5/8 inch
thickness 1.0 mm, 3/64 inch
A12, A18 A24, A42
ø12.7, 1/2" ø15.88, 5/8"
ø6.35, 1/4" ø9.52, 3/8"
5