Panasonic CS-VG120KE, Service Manual, Page: 47 / 80

6. After taking the steps above, keep the nitrogen gas flowing until the piping cools down to a certain extent (i.e. temperature at
which pipes are touchable with finger).
7. Completely remove the flux after brazing.
Fig. 14 Prevention of Oxidation during Brazing
* Cautions during brazing
1. General Cautions
a. The brazing strength should be high as required.
b. After operation, airtightness should be kept under pressurized condition.
c. During brazing do not allow component materials to become damaged due to overheating.
d. The refrigerant pipe work should not become blocked with scale or flux.
e. The brazed part should not restrict the flow in the refrigerant circuit.
f.
No corrosion should occur from the brazed part.
2. Prevention of Overheating
Due to heating, the interior and exterior surfaces of treated metal may oxidize. Especially, when the interior of the refrigerant
circuit oxidizes due to overheating, scale occurs and stays in the circuit as dust, thus exerting a fatally adverse effect. So, make
brazing at adequate brazing temperature and with a minimum of heating area.
3. Overheating Protection
In order to prevent components near the brazed part from overheating damage or quality deterioration due to flame or heat,
take adequate steps for protection such as (1) by shielding with a metal plate, (2) by using a wet cloth, and (3) by means of heat
absorbent.
4. Movement during Brazing
Eliminate all vibration during brazing to protect brazed joints from cracking and breakage.
5. Oxidation Preventative
In order to improve the brazing efficiency, various types of antioxidant are available on the market. However, the constituents
of these are widely varied, and some are anticipated to corrode the piping materials, or adversely affect HFC refrigerant,
lubricating oil, etc. Exercise care when using an oxidation preventive.
10.4.7. Servicing Tips
The drier must also be replaced whenever replacing the refrigerant cycle parts. Replace the refrigerant cycle parts first
before replacing the drier.The drier is supplied in a vacuum pack. Perform brazing immediately after opening the vacuum
pack, and then start the vacuum within two hours.In addition, the drier also needs to be replaced when the refrigerant has
leaked completely.
47
CS-VG120KE / CU-VG120KE