Mitsubishi Electric PURY-P350YJM-A [19/39] Airtight test evacuation and refrigerant charging

After evacuation and refrigerant charging, 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, four-way valve, etc.

Determine the amount of additional refrigerant charge by using the formula,

and charge refrigerant additionally through the service port after completing

piping connection work.

After completing work, tighten the service port and cap securely so as not to

generate any gas leakage. (Refer to the table on the below for appropriate

tightening torque.)

Appropriate tightening torque:

Outer

diameter of

copper pipe

(mm)

Cap (N·m) Shaft (N·m)

Size of

hexagonal

wrench

(mm)

Service port

(N·m)

ø9.52 15 6 4

ø12.7 20 9 4

ø15.88 25 15 6

ø19.05 25 30 8

ø25.4 25 30 8

ø28.58 25 – – 16

Caution:

Keep the valve closed until refrigerant charging to the pipes to be

added on site has been completed. Opening the valve before charging

the refrigerant may cause damage to the unit.

Do not use a leak detection additive.

[Fig. 10.2.3] (P.6)

A Example of closure materials (ﬁ eld supply)

B Fill the gap at the site

*When not attaching a low-pressure twinning pipe.

•

Make sure to seal-off the space around areas where the wires and refrigerant

pipes enter the unit to ensure that small animals, rainwater, or snow cannot

enter the unit through such openings and cause damage to the unit.

Caution:

Make sure to seal-off the openings for the pipe and wire retrieval.

Small animals, rainwater, or snow entering through the openings may

cause damage to the device.

10.3. Airtight test, evacuation, and

refrigerant charging

1 Airtight test

Perform with the valve of the outdoor unit closed, and pressurize the

connection piping and the indoor unit from the service port provided on the

valve of the outdoor unit. (Always pressurize from both the high-pressure

pipe and the low-pressure pipe service ports.)

[Fig. 10.3.1] (P.7)

Nitrogen gas

To indoor unit

System analyzer

Low knob

Hi knob

Valve

Low-pressure pipe

High-pressure pipe

Outdoor unit

Service port

Observe the following restrictions when conducting an air tightness test

to prevent negative effects on the refrigerating machine oil. Also, with

nonazeotropic refrigerant (R410A), gas leakage causes the composition to

change and affects performance. Therefore, perform the airtightness test

cautiously.

•

Caution:

Only use refrigerant R410A.

- The use of other refrigerants such as R22 or R407C, which contains chlorine,

will deteriorate the refrigerating machine oil or cause the compressor to

malfunction.

2 Evacuation

Evacuate with the valve of the outdoor unit closed and evacuate both the

connection 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 the high-pressure pipe and the low-pressure pipe.) After

the vacuum reaches 650 Pa [abs], 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, water might have entered. Apply pressure to dry

nitrogen gas up to 0.05 MPa and vacuum again.) Finally, seal in with the

liquid refrigerant through the high-pressure pipe, and adjust the low-pressure

piping to obtain an appropriate amount of the refrigerant during operation.

* Never perform air purging using refrigerant.

[Fig. 10.3.2] (P.8)

System analyzer

Low knob

Hi knob

Valve

Low-pressure pipe

High-pressure pipe

Service port

Three-way joint

Valve

R410A cylinder

Scale

Vacuum pump

To indoor unit

Outdoor unit

Note:

Always add an appropriate amount of refrigerant. Also always charge

the system with liquid refrigerant.

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.)

Use a vacuum pump with a reverse ﬂ ow check valve.

(Recommended vacuum gauge: ROBINAIR 14830A Thermistor Vacuum

Gauge)

Also use a vacuum gauge that reaches 65 Pa [abs] or below after

operating for ﬁ ve minutes.

3 Refrigerant 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

refrigerant by turning the cylinder upside-down as shown in Fig.10.3.3. If

the cylinder has a syphon pipe like that shown in the picture on the right,

the liquid refrigerant can be charged with the cylinder standing upright.

Therefore, give careful attention to the cylinder speciﬁ cations. If the unit

should be charged with gas refrigerant, replace all the refrigerant with new

refrigerant. Do not use the refrigerant remaining in the cylinder.

[Fig. 10.3.3] (P.8)

Syphon pipe

In case of the R410A cylinder having no syphon pipe.

•

Airtight test procedure Restriction

(1) After pressurizing to the design pressure (4.15 MPa) using nitrogen gas, allow it to

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 ﬂ are connection parts, brazed

parts, and other parts that may leak with a bubbling agent (Gupoﬂ ex, etc.) and visually

check for bubbles.

(3) After the airtight test, wipe off the bubbling agent.

If a ﬂ ammable gas or air (oxygen) is used as the pressurization

gas, it may catch ﬁ re or explode.

•

WT05963X01_GB.indd 19WT05963X01_GB.indd 19 2010/08/26 20:39:472010/08/26 20:39:47

Mitsubishi Electric PURY-P350YJM-A [19/39] Airtight test evacuation and refrigerant charging

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