Panasonic CU-YL28HBE5 Service Manual page 33

2. Installation work
a. Brazing work
Brazing work needs replacing air inside pipe with nitrogen gas in order to prevent oxidization scale from occurring. This is
called nitrogen replacement, and one of very important work in brazing refrigerant piping. (Oxidation preventive is not
possible to use)
b. Prevention measure for refrigerant piping
Prevention measure for refrigerant piping is very important work to prevent water-dust-rubbish from getting in.
All piping terminals needs sealing such as shown below.
• How to pinch
Close terminal part of piping with pliers and seal the
gap with brazing.
• How to tape
Seal terminal part of piping with vinyl tape.
3. Vacuum pumping
The purpose of vacuum pumping work is to remove and dry air inside the piping or nitrogen at air tightness test.
Perform the work carefully.
Vacuuming time
4. Refrigerant filling
Refrigerant filling must be done in the state of liquid refrigerant.
If this is done in gas refrigerant, the balance of refrigerant composition will collapse and damage the operation.
For the use of a gas cylinder without siphon inside, turn it upside down and use it.
(We recommend manifold with sight glass.)
Place
Outside More than 1 month
Less than 1 month
Inside
Use the vacuum pump with the backflow prevention mechanism to prevent backflow of oil.
60 minutes or more
Period of work
Not specified
Vacuum pump capacity 60 l/min or more
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Method of seal
Pinch
Pinch or taping