Mitsubishi Electric M Series Manual page 570

MULTI SYSTEM Inverter Heat Pump
5. Installing the refrigerant piping
Front piping cover
Piping cover
Stop valve
Service panel
Bend radius : 100 mm - 150 mm
Fig. 5-6
(1) (2)
Type A Type B
Fig. 5-7
(3)
Type C
Fig. 5-8
Fig. 5-9
C-568
HI
LO
5.6. Refrigerant piping (Fig. 5-6)
Remove the service panel (3 screws) and the front piping cover
and rear piping cover (2 screws).
Refrigerant pipes are protectively wrapped.
• The pipes can be protectively wrapped up to a diameter of ø90 before or after
connecting the pipes. Cut out the knockout in the pipe cover following the groove
and wrap the pipes.
Pipe inlet gap
• Use putty or sealant to seal the pipe inlet around the pipes so that no gaps remain.
(If the gaps are not closed, noise may be emitted or water and dust will enter the
unit and breakdown may result.)
5.7. Caution for piping connection/valve operation
• Conduct piping connection and valve operation accurately by following the figure
below.
• Apply sealer along the insulator to prevent water entering the insulator covering the
refrigerant pipe joints.
• After evacuation and refrigerant charge, ensure that the handle is fully open. If
operating with the valve closed, abnormal pressure will be imparted to the high- or
low-pressure side of the refrigerant circuit, giving damage to the compressor, etc.
• Determine the amount of additional refrigerant charge (refer "5.3. Addition of refrig-
erant"), and charge refrigerant additionally through the service port after complet-
ing piping connection work.
• After completing work, tighten the service port (12 - 15 N·m) and cap (20 - 25 N·m)
securely to prevent gas leak.
*1 N·m 10 kgf·cm
Method of completely opening the stop valve
The stop valve opening method varies according to the outdoor unit model. Use the
appropriate method to open the stop valves.
(1) Type A (Fig. 5-7)
Remove the cap, then turn one-quarter rotation counter-clockwise with a flat-bladed
screwdriver to complete open.
Check that the valves are fully open, then return the cap to its original state and
tighten it down.
(2) Type B (Fig. 5-7)
Remove the cap, pull the handle toward you and rotate 1/4 turn in a counterclock-
wise direction to open.
Make sure that the stop valve is open completely, push in the handle and rotate
the cap back to its original position.
(3) Type C (Fig. 5-8)
Remove the cap and turn the valve rod counterclockwise as far as it will go with
the use of a 4 mm hexagonal wrench. Stop turning when it hits the stopper.
Make sure that the stop valve is open completely and rotate the cap back to its
original position.
Valve
Unit side
Service port
Handle
Cap
Completely closed
5.8. Airtight test and evacuation
Airtight test (Fig. 5-9)
Airtight test should be made by pressurizing nitrogen gas. For the test method, refer
to the following figure.
(1) Connecting the testing tool. Make a test with the stop valve closed. Be also sure to
pressurize both liquid or high-pressure pipe and gas or low pressure pipe.
(2) Do not add pressure to the specified pressure all at once; add pressure little by little.
Pressurize to 0.5 MPa (5 kgf/cm
pressure does not decrease.
Pressurize to 1.5 MPa (15 kgf/cm
pressure does not decrease.
Pressurize to 4.15 MPa (41.5 kgf/cm
perature and refrigerant pressure.
(3) If the specified pressure holds for about one day and does not decrease, the pipes
have passed the test and there are no leaks.
• If the surrounding temperature changes by 1 °C, the pressure will change by
about 0.01 MPa (0.1 kgf/cm G). Make the necessary corrections.
2
(4) If the pressure decreases in steps (2) or (3), there is a gas leak. Look for the
source of the gas leak.
Nitrogen gas
System analyzer
Lo-knob
Hi-knob
To branch box
M series
(2 screws)
Completely open
(On-side installation) Refrigerant piping side
Direction the refrigerant flows in
Wrench hole
Operation section
G), wait 5 minutes, and make sure the
2
G), wait 5 minutes, and make sure the
2
G) and measure the surrounding tem-
2
Outdoor unit
Stop valve
Liquid pipe or high-pressure pipe
Gas pipe or low-pressure pipe
Service port