Daikin Emura RXJ20A5V1B Service Manual page 191

Refrigerant circuit vacuuming - general advice
RXJ20~50A + FTXJ-A(W)(S)(B)
Split Emura 3 R32
ESIE22-04B – 2022.08
▪ Pipe expansion / flare making:
- Remove any burrs on the cut surface using the correct tool such as reamer or
scraper (note that excessive deburring can thin the pipe walls and cause
cracking of the pipe).
- Make sure the flare has the correct size (use a flare gauge).
- Make sure no particles remain in the piping.
- Apply just a drop of refrigerant oil on the inner surface of the flare.
- Make sure the flare connection is tightened with the correct torque (torque
values refer to installation manual).
▪ Brazing:
- Use the correct brazing tool.
- Use a phosphor copper filler metal (silver composition of 0 to 2%). Do not use
flux material.
- Flush the piping before brazing with nitrogen to avoid oxidation of the inside of
the copper tubes (nitrogen purity ≥99.99%).
The effectiveness of the vacuum drying depends on many factors. Besides
following the correct procedures and using equipment that is well maintained, the
ambient conditions at which the vacuum is done MUST be considered. If there is
moisture in the refrigerant and the ambient temperature is lower, the vacuum
pressure that MUST be reached to allow the evaporation of the moisture will need
to be lower. In some cases the vacuum pump may NOT be able to achieve these
pressures. If possible, heat the locations where moisture is expected.
As a general target, the values below CAN be used as reference to achieve a proper
vacuum on the unit:
▪ Absolute pressure below 270 Pa MUST be reached. The time needed for the
pressure to lower is also depending on the moisture amount. If it takes very long
or it is hard to reach the pressure, this MIGHT be an indication of moisture
presence, so the vacuum pump will need to run longer.
▪ After stopping the vacuum pump, the absolute pressure MUST be kept below
270 Pa for at least 30 minutes, without a significant increase of pressure. If
pressure increases significantly, this is an indication of the presence of moisture
in the system.
▪ If multiple vacuum cycles need to be performed, break the vacuum between the
cycles using dry nitrogen.
Depending on the site conditions, as mentioned above, lower pressure values
MIGHT be needed to allow the boiling of the moisture in the system. The table
below shows the boiling point of water for different absolute pressures.
Pressure (absolute)
Micron / Torr
760000 / 760
50000 / 50
10000 / 10
2000 / 2
1000 / 1
500 / 0.5
5 Third party components
|
Mbar / Pa
1013 / 101325
66 / 6666
13 / 1333
2.6 / 266
1.33 / 133
0.66 / 66
Boiling point
°C
100
38
11
−10
−18
−24
Service manual
191