Installing The Refrigerant Piping; Precautions For Devices That Use R407C Refrigerant - Mitsubishi Electric Mr. Slim PU-P-GAA Serie Manual De Instalación

4. Installing the refrigerant piping

A
45°±2°
A Flare cutting dimensions
B Flare nut tightening torque
Fig. 4-1
Table 1 (Fig. 4-1)
Copper pipe O.D. Flare dimensions
(mm) øA dimensions (mm)
ø6.35
ø9.52 12.6 - 13.0
ø12.7 15.8 - 16.2
ø15.88 19.3 - 19.7
ø19.05 22.9 - 23.3
D
A
Fig. 4-2
B
A
C
D
E
F
G
Fig. 4-3
B
C
D
Tightening torque
(N·m)
8.6 - 9.0 14 - 18
35 - 42
50 - 58
75 - 80
100 - 120
C
A Front piping cover
B
E B Pipling cover
C Stop valve
D Service panel
E Band radius : 100 mm-150 mm
A Stop valve <Liquid side>
B Stop valve <Gas side>
H
C Service port
D Open/Close section
E Local pipe
F Sealed, same way for gas side
G Pipe cover
I
H Do not use a wrench here.
Refrigerant leakage may result.
I Use two wrenches here.

4.1. Precautions for devices that use R407C refrigerant

• Do not use the existing refrigerant piping.
• Do not use crushed, misshapen, or discolored tubing. The inside of the tub-
ing should be clean and free from harmful sulfuric compounds, oxidants,
dirt, debris, oils and moisture.
• Store the piping to be used during installation indoors and keep both ends of
the piping sealed until just before brazing.
• Use ester oil, ether oil or alkylbenzene (small amount) as the refrigerator oil
to coat flares and flange connections.
• Use liquid refrigerant to fill the system.
• Do not use a refrigerant other than R407C.
• Use a vacuum pump with a reverse flow check valve.
• Do not use the tools that are used with conventional refrigerants.
• Do not use a charging cylinder.
• Be especially careful when managing the tools.
• Do not use commercially available dryers.
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 or more,
thickness of 12 mm 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 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 as attached to the unit. D
• When bending the pipes, be careful not to break them. Bend radii of 100 mm to 150
mm 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).
Refrigerant Piping Sizes
Model
P25
Item
Refrigerant Liquid O.D. ø6.35 (1/4") O.D. ø9.52 (3/8") O.D. ø9.52 (3/8")
piping Gas O.D. ø12.7 (1/2") O.D. ø15.88 (5/8") O.D. ø19.05 (3/4")
4.3. Refrigerant piping (Fig. 4-2), (Fig. 4-3)
Remove the service panel D (three screws) and the front piping cover A (one screw)
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 (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.
P35, 50, 60, 71 P100, 125, 140
5