Brazing Work - LG Multi F A2UW14GFA0 Engineering Product Data Book

2. Guideline for each installation process

2.2.4 Brazing work

CAUTION
Brazing of refrigerant piping :
The following precaution should be taken.
1. Do not use flux when brazing copper to copper
refrigerant piping.
(Particularly for the HFC refrigerant piping)
Therefore, use the phosphor copper brazing filler metal
(BCuP) which does not require flux.
(Flux has extremely harmful influence on refrigerant pip-
ing systems. For instance, if the chlorine based flux is
used, it will cause pipe corrosion or, in particular, if the
flux contains fluorine, it will damage the refrigerant oil.)
1) Niorogen flushing method (During brazing)
Brazing section
Taping
CAUTION
Nitrogen brazing
a. This procedure is designed to prevent formation of
oxidation film by filling piping with inert gas. Note that
excessive gas pressure will generate pinholes at
brazed points. (Nitrogen gas: Supply pressure
0.05~0.1kg/cm 2 G)
b. When supplying inert gas, be sure to open one end of
piping.
11 _
Heat pump 50Hz/R410A
Copper pipe 1/4
Pressure regulator
Packless
valve
Nitrogen cylinder
High
pressure hose
Packless
valve
Outdoor unit
Hose
Pressure
Pipe
regulator
Nitrogen cylinder
If brazing work is carried out without passing nitrogen gas
through the pipes then it allows the formation of
oxidation bubbles on the inside surface of the pipes.
These oxidation bubbles are then carried along inside the
pipes to cause damage to various members of the system
such as valve or compressors and the system ceases to
function properly.
In order to avoid this problem nitrogen is passed through
the pipe while the soldering work is being carried out.
This operation work is known as nitrogen
replacement.(Air is replaced by nitrogen)
This is standard work during all brazing works.
CAUTION
Water enters
Make sure to keep the connecting piping dry (away
from water) , clean (away from dust) , and air tight
(avoid refrigerant leakage)
CAUTION
Pipe bending
Annealed copper pipe with small diameter (Ø6.35 or
Ø9.52) can be easily bent manually. In this case, secure
large R (radius) for the bend section and gradually bend
pipe. If annealed copper pipe is large in diameter
(Ø15.88 or over), bend pipe with bender. Use bender
appropriate for the pipe diameter.
(Direction of nitrogen gas.)
Nitrogen brazing
Plaster enters
N
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