Mitsubishi Electronics PUHY-HP-THMU-A Airtight test, evacuation, and refrigerant charging

Caution:

•Always remove the connecting pipe from the valve and braze it outside the unit.

-Brazing the connecting pipe while it is installed will heat the valve and cause trouble or gas leakage. The piping, etc. inside the unit may also be burned.

•Use ester oil, ether oil or alkylbenzene (small amount) as the refrigerat- ing machine oil to coat flares and flange connections.

-The refrigerating machine oil will degrade if it is mixed with a large amount of mineral oil.

•Keep the valve closed until refrigerant charging to the pipes to be added on site has been completed. Opening the valve before charging the re- frigerant may result in unit damage.

•Do not use a leak detection additive. [Fig. 10.2.4]

AB

AExample of closure materials (field supply)

BFill the gap at the site

Caution:

Make sure to seal-off and excess space around areas where the wires and refrigerant pipes enter the unit.

•Small animals and rainwater entering through the openings may cause damage to the device.

10.3. Airtight test, evacuation, and refrigerant charging

1Airtight test

Perform with the valve of the outdoor unit closed, and pressurize the connec- tion piping and the indoor unit from the service port provided on the valve of the outdoor unit. (Always pressurize from both the liquid pipe and the gas pipe service ports.)

[Fig. 10.3.1]

			F
		B	G
		B	H
	LO	C	I
A		HI
	D	E	J
C
A Nitrogen gas		B To indoor unit	C System analyzer
D Lo knob		E Hi knob	F Valve
G Liquid pipe		H Gas pipe	I Outdoor unit

JService port

GB

Make sure to seal-off and excess space around areas where the wires and		Observe the following restrictions when conducting an air tightness test to prevent
refrigerant pipes enter the unit to ensure that small animals and rainwater cannot
		negative effects on the refrigerating machine oil. Also, with nonazeotropic refriger-
enter the unit through such openings and cause damage to the unit.
		ant (R410A), gas leakage causes the composition to change and affects perform-
		ance. Therefore, perform the airtightness test cautiously.
	Airtight test procedure		Restriction
1. Nitrogen gas pressurization			• If a flammable gas or air (oxygen) is used as the pressurization
(1)	After pressurizing to the design pressure (4.15 MPa [602 psi]) using nitrogen gas, allow it to		gas, it may catch fire or explode.
	stand for about one day. If the pressure does not drop, airtightness is good.
	However, if the pressure drops, since the leaking point is unknown, the following bubble test
	may also be performed.
(2)	After the pressurization described above, spray the flare connection parts, brazed parts, flanges,
	and other parts that may leak with a bubbling agent (Kyuboflex, etc.) and visually check for
	bubbles.
(3)	After the airtight test, wipe off the bubbling agent.
2. Pressurization using refrigeration gas and nitrogen gas			• Do not use a refrigerant other than that indicated on the unit.
(1)	After first pressurizing with R410A liquid refrigerant to a gas pressure of approximately 0.2		• Sealing with gas from a cylinder will cause the composition of
	Mpa [29 psi], pressurize to the design pressure of 4.15 Mpa [602 psi] using nitrogen gas.		the refrigerant in the cylinder to change.
	However, do not pressurize at one time. Stop during pressurization and check that the pres-		• Use a pressure gauge, charging hose, and other parts especially
	sure does not drop.		designed for use with R410A.
(2)	Check for gas leaks by checking the flare connection parts, brazed parts, flanges, and other		• An electric leak detector for R22 cannot detect leaks of R410A.
	parts which may leak using an R410A compatible electric leak detector.		• Do not use a haloid torch. (Leaks cannot be detected.)
(3)	This test may be used together the with bubble type gas leak test.

Caution:

Only use refrigerant R410A.

-The use of other refrigerant such as R22 or R407C, which contains chlorine, will deteriorate the refrigerating machine oil or cause the compressor to malfunction.

2Evacuation

Evacuate with the valve of the outdoor unit closed and evacuate both the con- nection piping and the indoor unit from the service port provided on the valve of the outdoor unit using a vacuum pump. (Always evacuate from the service port of both liquid pipe and gas pipe.) After the vacuum reaches 650 Pa [abs] [0.0943 psi/5 Torr], continue evacuation for at least one hour or more. Then, stop the vacuum pump and leave it for 1 hour. Ensure the degree of vacuum has not increased. (If the degree of vacuum increase is larger than 130 Pa [0.01886 psi/1.0 Torr], water might have entered. Apply pressure to dry nitrogen gas up to 0.05 MPa [7.25 psi] and vacuum again.) Finally, seal in with the liquid refrigerant through the liquid pipe, and adjust the gas piping to obtain an appropriate amount of the refrigerant during operation.

*Never perform air purging using refrigerant.

[Fig. 10.3.2]

D

N E

N		F
A		O
	HI
LO		G
B	C
	H	I

		K
		J
		L
A System analyzer	B Lo knob
D Valve	E Liquid pipe
G Service port	H Three-way joint
J Valve	K R410A cylinder
M Vacuum pump	N To indoor unit

M

CHi knob

FGas pipe

IValve

LScale

OOutdoor unit

11