Mitsumi electronic PQHY-P7296TGMU-A Airtight test, evacuation, and refrigerant charging

Note:

If a torque wrench is not available, use the following method as a standard: When you tighten the flare nut with a wrench, you will reach a point where the tightening torque will abruptly increase. Turn the flare nut beyond this point by the angle shown in the table above.

Caution:

•Always remove the connecting pipe from the ball valve and braze it out- side the unit.

-Brazing the connecting pipe while it is installed will heat the ball 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 ball valve closed until refrigerant charging to the pipes to be added on site has been completed. Opening the valve before charging the refrigerant may result in unit damage.

•Do not use a leak detection additive.

9.3. Airtight test, evacuation, and refrigerant charging

1Airtight test

Perform with the ball valve of the heat source unit closed, and pressurize the connection piping and the indoor unit from the service port provided on the ball valve of the heat source unit. (Always pressurize from both the Gas pipe and the Liquid pipe service ports.)

[Fig. 9.3.1] (P.4)

A Nitrogen gas		B To indoor unit		C System analyzer
D	Lo knob	E	Hi knob	F	Ball valve
G	Liquid pipe	H	Gas pipe	I	Heat source unit

JService port

Observe the following restrictions when conducting an air tightness test to prevent negative effects on the refrigerating machine oil. Also, with nonazeotropic refriger- 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	GB
(1)	After pressurizing to the design pressure (4.15 MPa [601 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 refrigerant gas and nitrogen gas		• Do not use a refrigerant other than that indicated on the unit.
(1)	Pressurizing to a gas pressure of approximately 0.2 MPa [29 psi], pressurize to the design	• Sealing with gas from a cylinder will cause the composition of
	pressure (4.15 MPa [601 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.	for 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.

[Fig. 9.3.3] (P.4)

A Syphon pipe B In case of the cylinder having no syphon pipe.

2 Evacuation 9.4. Thermal insulation of refrigerant piping

Evacuate with the ball valve of the heat source unit closed and evacuate both the connection piping and the indoor unit from the service port provided on the ball valve of the heat source unit using a vacuum pump. (Always evacuate from the service port of both the gas pipe and the liquid pipe.) After the vacuum reaches 650 Pa [abs] [0.0943 psi/5 Torr], continue evacuation for at least one hour or more.

* Never perform air purging using refrigerant.

[Fig. 9.3.2] (P.4)

A System analyzer		B Lo knob		C Hi knob
D Ball valve		E Liquid pipe		F Gas pipe
G Service port		H Three-way joint		I Valve
J	Valve	K	R410A cylinder	L	Scale
M	Vacuum pump	N	To indoor unit	O	Heat source unit

Note:

•Always add an appropriate amount of refrigerant. Also always seal the system with liquid refrigerant.Too much or too little refrigerant will cause trouble.

•Use a gauge manifold, charging hose, and other parts for the refrigerant indicated on the unit.

•Use a graviometer. (One that can measure down to 0.1 kg [4 oz])

•Use a vacuum pump with a reverse flow check valve.

(Recommended vacuum gauge: ROBINAIR 14830A Thermistor Vacuum Gauge)

Also use a vacuum gauge that reaches 65 Pa [abs] [0.00943 psi/0.5 Torr] or below after operating for five minutes.

3Refrigerant Charging

Since the refrigerant used with the unit is nonazerotropic, it must be charged in the liquid state. Consequently, when charging the unit with refrigerant from a cylinder, if the cylinder does not have a syphon pipe, charge the liquid refriger- ant by turning the cylinder upside-down as shown in Fig.9.3.3. If the cylinder has a syphon pipe like that shown in the picture on the right, the liquid refriger- ant can be charged with the cylinder standing upright. Therefore, give careful attention to the cylinder specifications. If the unit should be charged with gas refrigerant, replace all the refrigerant with new refrigerant. Do not use the re- frigerant remaining in the cylinder.

Be sure to give insulation work to refrigerant piping by covering high press. (liquid) pipe and low press. (gas) pipe separately with enough thickness heat-resistant polyethylene, so that no gap is observed in the joint between indoor unit and insu- lating material, and insulating materials themselves. When insulation work is insuf- ficient, there is a possibility of condensation drip, etc. Pay special attention to insu- lation work to ceiling plenum.

[Fig. 9.4.1] (P.4)

A	Steel wire	B	Piping
C	Asphaltic oily mastic or asphalt	D	Heat insulation material A

EOuter covering B

Heat	Glass fiber + Steel wire
insulation	Adhesive + Heat - resistant polyethylene foam + Adhesive tape
material A
Outer	Indoor	Vinyl tape
	Floor exposed	Water-proof hemp cloth + Bronze asphalt
covering B
	Heat source	Water-proof hemp cloth + Zinc plate + Oily paint

Note:

•When using polyethylene cover as covering material, asphalt roofing shall not be required.

•No heat insulation must be provided for electric wires.

[Fig. 9.4.2] (P.4)

A	Liquid pipe	B	Gas pipe	C Electric wire
D	Finishing tape	E	Insulator

[Fig. 9.4.3] (P.4)

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