25
5.5
Brazing
Care
must
be
taken
to
prevent
oxide
forming
on
the
inside
of
copper
piping
during
brazing.
The
presence
of
oxide
in
a
refrigerant
system
adversely
affects
the
operation
of
valves
and
compressors,
potentially
leading
to
low
efficiency
or
even
compressor
failure.
To
prevent
oxidation,
during
brazing
nitrogen
should
be
flowed
through
the
refrigerant
piping.
Box
continued
on
next
page
…
Warning
Never
flow
oxygen
through
piping
as
doing
so
aids
oxidation
and
could
easily
lead
to
explosion
and
as
such
is
extremely
dangerous.
Take
appropriate
safety
precautions
such
as
having
a
fire
extinguisher
to
hand
whilst
brazing.
Flowing
nitrogen
during
brazing
Use
a
pressure
reducing
valve
to
flow
nitrogen
through
copper
piping
at
0.02
‐
0.03MPa
during
brazing.
Start
the
flow
before
brazing
starts
and
ensure
that
the
nitrogen
continuously
passes
through
the
section
being
brazed
until
the
brazing
is
complete
and
the
copper
has
cooled
down
completely.
Figure
3
‐
5.4:
Flowing
nitrogen
through
piping
during
brazing
Legend
1
Copper
piping
2
Section
being
brazed
3
Nitrogen
connection
4
Hand
valve
5
Pressure
‐
reducing
valve
6
Nitrogen
When
joining
a
shorter
section
of
piping
to
a
longer
section,
flow
nitrogen
from
the
shorter
side
to
allow
better
displacement
of
air
with
nitrogen.
If
the
distance
from
the
point
where
nitrogen
enters
the
piping
to
the
joint
to
be
brazed
is
long,
ensure
that
the
nitrogen
is
flowed
for
sufficient
time
to
discharge
all
the
air
from
the
section
to
be
brazed
before
commencing
brazing.
Figure
3
‐
5.5:
Flowing
nitrogen
from
shorter
side
during
brazing
Notes
for
installers
1
2
3
4
5
6
6
B r a z i n g
E l b o w j o i n t
S h o r t e r s e c t i o n o f p i p i n g
N i t
r o
g e
n
N i t r o g e n
B r a z i n g
S h o r t e r s e c t i o n o f p i p i n g
S e c t i o n b e i n g b r a z e d
