31
5.9.3
Leak
detection
5.10
Vacuum
Drying
5.10.1
Purpose
Vacuum
drying
should
be
performed
in
order
to
remove
moisture
and
non
‐
condensable
gases
from
the
system.
Removing
moisture
prevents
ice
formation
and
oxidization
of
copper
piping
or
other
internal
components.
The
presence
of
ice
particles
in
the
system
would
cause
abnormal
operation,
whilst
particles
of
oxidized
copper
can
cause
compressor
damage.
The
presence
of
non
‐
condensable
gases
in
the
system
would
lead
to
pressure
fluctuations
and
poor
heat
exchange
performance.
Vacuum
drying
also
provides
additional
leak
detection
(in
addition
to
the
gastightness
test).
The
general
methods
for
identifying
the
source
of
a
leak
are
as
follows:
1. Audio
detection:
relatively
large
leaks
are
audible.
2. Touch
detection:
place
your
hand
at
joints
to
feel
for
escaping
gas.
3. Soapy
water
detection:
small
leaks
can
be
detected
by
the
formation
of
bubbles
when
soapy
water
is
applied
to
a
joint.
4. Refrigerant
leak
detection:
for
leaks
that
are
difficult
to
detect,
refrigerant
leak
detection
may
be
used
as
follows:
a) Pressurize
the
piping
with
nitrogen
at
0.3MPa.
b) Add
refrigerant
into
the
piping
until
the
pressure
reaches
0.5MPa.
c)
Use
a
halogen
refrigerant
detector
to
find
the
leak.
d) If
the
leak
source
cannot
be
found,
continuing
charging
with
refrigerant
to
a
pressure
of
4MPa
and
then
search
again.
Notes
for
installers
