Mitsubishi Electric MXZ-8B140, Руководство по установке

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5. Installing the refrigerant piping
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 refriger-
ant”), and charge refrigerant additionally through the service port after completing
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. 5-9)
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. 5-9)
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. 5-10)
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 Completely open
Unit side (On-side installation) Refrigerant
piping side
Service port
Handle Direction the refrigerant flows in
Cap Wrench hole
Completely closed Operation section
LO
HI
A
C D
B
K
E F
G
H
I
Fig. 5-11
5.8. Airtight test and evacuation
Airtight test (Fig. 5-11)
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 lit-
tle.
Pressurize to 0.5 MPa (5 kgf/cm 2 G), wait five minutes, and make sure the
pressure does not decrease.
Pressurize to 1.5 MPa (15 kgf/cm
2
G), wait five minutes, and make sure the
pressure does not decrease.
Pressurize to 4.15 MPa (41.5 kgf/cm 2 G) and measure the surrounding tem-
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
2
G). Make the necessary corrections.
(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 Stop valve
System analyzer Liquid pipe or high-pressure
pipe
Lo-knob
Hi-knob Gas pipe or low-pressure pipe
To branch box Service port
Outdoor unit
Fig. 5-9
Fig. 5-10
Type A Type B
F
H
C
A
B
D
E
G
B
C
J
I
H
E
(1) (2)
(3)
Type C
A
B
K
E
H
C
5.6. Refrigerant piping (Fig. 5-8)
Remove the service panel (three screws) and the front piping cover (two screws)
and rear piping cover (two screws).
Refrigerant pipes are protectively wrapped
• The pipes can be protectively wrapped up to a diameter of ø90 before or after con-
necting 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 re-
main.
(If the gaps are not closed, noise may be emitted or water and dust will enter the
unit and breakdown may result.)
Fig. 5-8
Front piping cover
Piping cover
Stop valve
Service panel
Band radius : 100 mm - 150 mm