Refrigerant Charging - Mitsubishi Electric CITY MULTI Manual De Instalación

Airtight test procedure
(1) After pressurizing to the design pressure (4.15 MPa [602 psi]) 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 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.
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.
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] [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. Repeat the evacuation process three
or more times until the vacuum pressure is lost by 130 Pa or below.)
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]
D
N
N
O
A
LO HI
G
C
B
H
A System analyzer B Lo 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
[Fig. 10.3.3]
<If the cylinder does not have a siphon pipe, charge with the refrigerant cylinder upside-down.>
A Siphon pipe
E
F
I
M
K
J
L
C Hi knob
F High-pressure pipe
I Valve
L Scale
O Outdoor unit
Restriction
• If a flammable gas or air (oxygen) is used as the pressurization gas, it may
catch fire or explode.
Note:
- For evacuation, the following procedures can be referred.
• 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 [3 oz].)
• Use a vacuum pump with a reverse flow check valve.
(Recommended vacuum gauge: ROBINAIR 14830A Thermistor Vacuum
Gauge or Micron Gauge)
Do not use a manifold gauge to measure vacuum pressure.
Also use a vacuum gauge that reaches 65 Pa [abs] [0.00943 psi/
0.5 Torr] or below after operating for five minutes.
<Triple Evacuation>
• Evacuate the system to 4,000 microns from both service valves.
System manifold gauges must not be used to measure vacuum.
A micron gauge must be used at all times.
- Break the vacuum with Nitrogen (N2) into the discharge service valve to
0 PSIG.
• Evacuate the system to 1,500 microns from the suction service valve.
- Break the vacuum with Nitrogen (N2) into the discharge service valve to
0 PSIG.
• Evacuate the system to 500 microns. System must hold the vacuum at
500 microns for a minimum of 1 hour.
• Conduct a rise test for a minimum of 30 minutes.

3 Refrigerant Charging

• Do not use refrigerant other than the type indicated in the manuals
provided with the unit and on the nameplate.
- Doing so may cause the unit or pipes to burst, or result in explosion or fire
during use, during repair, or at the time of disposal of the unit.
- It may also be in violation of applicable laws.
- MITSUBISHI ELECTRIC CORPORATION cannot be held responsible
for malfunctions or accidents resulting from the use of the wrong type of
refrigerant.
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 siphon pipe, charge the liquid
refrigerant by turning the cylinder upside-down as shown in Fig.10.3.3. If
the cylinder has a siphon 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 specifications. 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.
A
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