Daikin FTXP20-71L Service Manual page 151

Refrigerant piping repair
Refrigerant circuit vacuuming - general advice
ATXP20~35 + FTXP20~71 + ARXP20~35 + RXP20~71
Split Comfora R32
ESIE18-01E – 2023.01
DANGER: RISK OF EXPLOSION
Pump down – Refrigerant leakage. If you want to pump down the system, and there
is a leak in the refrigerant circuit:
▪
Do NOT use the unit's automatic pump down function, with which you can collect
all refrigerant from the system into the outdoor unit. Possible consequence: Self-
combustion and explosion of the compressor because of air going into the
operating compressor.
▪
Use a separate recovery system so that the unit's compressor does NOT have to
operate.
CAUTION
Some outdoor units are equipped with a low pressure switch to protect the
compressor by switching it off. NEVER short‑circuit the low pressure switch during
pump down operation.
1 Remove the refrigerant connection cover, see
2 Remove the cap from the stop valves.
3 Perform pump down operation, see installer reference guide for the correct
procedure.
4 After 5~10 minutes (after only 1~2 minutes in case temperature <–10°C),
close the liquid stop valve using a hexagonal wrench.
5 Check the manifold if vacuum is reached. Close the gas stop valve and stop
forced cooling operation.
▪ Make sure to cover open pipe ends during repair so no dust or moisture can
enter.
▪ Make sure to re‑apply insulation removed during repair.
▪ 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
4 Third party components
|
4
"3.9 Plate work" [ 111].
Service manual
151