Carrier CDII-184R1-0CTR4 Installation & Operation Manual page 26

7.6 BRAZING OF PIPES
• Use any type of brazing filler other than phosphor bronze, in hot spring resort and
do paint coating on surface because phosphor brazing filler tends to react with
Sulphur & produce a fragile compound water solution which may cause gas leakage.
• Use same type of brazing filler every time of servicing/ brazing.
• Do not enter flux into the refrigerant cycle.
• Use flux which does not contain chlorine.
• Use only distilled water with flux.
• Remove flux after brazing.
As brazing work requires sophisticated techniques and experiences based on a theoretical
knowledge, it must be performed by carrier service person only.
To prevent oxide film from occurring in the pipe interior during brazing, it is effective to proceed
with brazing while letting dry Nitrogen gas (N2) flow.
Reason why flux is required:
1. It prevents metal surface from being oxidized and thus it assists brazing filler.
2. It helps to reduce surface tension of brazing filler and thus it adheres better to the metal.
Use Non-Corrosive flux
Generally, it is compound of borax and boric acid. It is effective in case where the brazing
temperature is higher than 800 deg C.
Material for brazing rod
Brazing Rod material
Brazing flame: Neutral flame (equal quantities of oxygen and acetylene).
Prevention from Oxidation during brazing:
1. Attach a reducing valve and a flow meter to the Nitrogen gas cylinder.
2. Use a copper pipe to direct the piping material and attach a flow meter to the cylinder.
3. Apply a seal onto the clearance between piping material and inserted copper pipe for
Nitrogen in order to prevent backflow of the Nitrogen gas.
4. When the Nitrogen gas is flowing be sure to keep the piping end open.
5. Adjust the flow rate of Nitrogen gas so that it is lower than 0.05m3/Hr or 0.02MPa(.2kgf/cm2)
by means of the reducing valve.
COPPER
CAUTION
PHOSPHOROUS
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Brazing Filler