Mitsubishi Electronics R410A Refrigerant piping Fig, Refrigerant pipe airtight testing method

4. Installing the refrigerant piping

D

AFront piping cover

C

B

4.3. Refrigerant piping (Fig. 4-4)

Remove the service panel D (three screws) and the front piping cover A (two screws) and rear piping cover B (two screws).

1Perform refrigerant piping connections for the indoor/outdoor unit when the out- door unit’s stop valve is completely closed.

2Vacuum-purge air from the indoor unit and the connection piping.

3After 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 and gas stop

valves. 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 out-

door units.

• If the stop valves are left closed and the unit is operated, the compressor and

control valves will be damaged.

B Piping cover
C Stop valve
D Service panel	A	E

EBend radius : 100 mm - 150 mm

Fig. 4-4

			B
			A
	C		H
	D
	E
	F		I
			C
	G
A Stop valve <Liquid side>			F Sealed, same way for gas side
B Stop valve <Gas side>			G Pipe cover
C Service port			H Do not use a wrench here.
D Open/Close section			Refrigerant leakage may result.
E Local pipe			I Use two wrenches here.
			Fig. 4-5
(1)
B			B
A		A	C
			D
J	D
G
	G		G	F
E			E
Type A		Type B
			Fig. 4-6
(2) 1 B G			2

D

H

EI

Fig. 4-7

• 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.

5Use sealant to seal the ends of the thermal insulation around the pipe connection sections to prevent water from entering the thermal insulation.

4.4.Refrigerant pipe airtight testing method

(1)Connect the testing tools.

•Make sure the stop valves A B are closed and do not open them.

•Add pressure to the refrigerant lines through the service port C of the liquid stop valve A and the gas stop valve B.

(2)Do not add pressure to the specified pressure all at once; add pressure little by little. 1 Pressurize to 0.5 MPa [73 PSIG], wait five minutes, and make sure the

pressure does not decrease.

2 Pressurize to 1.5 MPa [218 PSIG], wait five minutes, and make sure the pres- sure does not decrease.

3 Pressurize to 3.8 MPa [550 PSIG] and measure the surrounding temperature 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 [1.8°F], the pressure will change by about 0.01 MPa [1.5 PSIG]. 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.

4.5. Stop valve opening method

(1)Gas side (Fig. 4-6) Type A

1 Remove the cap, then turn one-quarter rotation counter-clockwise with a flat-bladed screwdriver to complete open.

2 Check that the valves are fully open, then return the cap to its original state and tighten it down.

Type B

1 Remove the cap, pull the handle toward you and rotate 1/4 turn in a counterclock- wise direction to open.

2 Make sure that the stop valve is open completely, push in the handle and rotate the cap back to its original position.

(2)Liquid side (Fig. 4-7)

1Remove the cap and turn the valve rod counterclockwise as far as it will go with the use of a 4 mm [5/32 inch] hexagonal wrench. Stop turning when it hits the stopper.

(ø6.35 [1/4 inch]: Approximately 4.5 revolutions) (ø9.52 [3/8 inch]: Approximately 10 revolutions)

2Make sure that the stop valve is open completely, push in the handle and rotate the cap back to its original position.

A Valve	F Open position side
B Unit side	G Service port
C Handle	H Wrench hole
D Cap	I Refrigerant flow direction
E Local pipe side	J Operation section

Refrigerant pipes are protectively wrapped

•The pipes can be protectively wrapped up to a diameter of ø90 mm [ø3-35/64 inch] before or after connecting the pipes. Cut out the knockout in the pipe cover follow-

ing 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.)

7