Airtight Test, Evacuation, And Refrigerant Charging - Mitsubishi Electric City Multi PURY-EP-YJM-A Installation Manual

• 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
Cap (N·m) Shaft (N·m)
copper pipe
(mm)
ø9.52 15
ø12.7 20
ø15.88 25
ø19.05 25
ø25.4 25
ø28.58 25
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.
(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.
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)
A System analyzer B Low knob
D Valve E Low-pressure pipe
G Service port H Three-way joint
J Valve K R410A cylinder
M Vacuum pump N To indoor unit
Size of
hexagonal Service port
wrench (N·m)
(mm)
6 4
9 4
15 6 12
30 8
30 8
– – 16
Airtight test procedure
C Hi knob
F High-pressure pipe
I Valve
L Scale
O Outdoor unit
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)
A Nitrogen gas B To indoor unit
D Low knob E Hi knob
G Low-pressure pipe H High-pressure pipe
J 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.
• If a fl ammable gas or air (oxygen) is used as the pressurization
gas, it may catch fi re or explode.
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)
A Syphon pipe B In case of the R410A cylinder having no syphon pipe.
C System analyzer
F Valve
I Outdoor unit
Restriction
19