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q
Vacuum-dehydrating (first time)
..... 2 hours
w
Vacuum-breaking (first time)
Nitrogen gas is pressurized to 0.5kg/cm
2
from the service port on suction pipe.
Since nitrogen gas breaks the vacuum, the
effect of the vacuum-dehydrating is
enhanced. However, if there is much
moisture, it can not be removed by this
method. Therefore, do not allow water
entry or produce water during the
refrigerant piping work.
e
Vacuum-dehydrating (second time)
Run the vacuum pump one hour or longer.
(The achievable vacuum must be
–755mmHg or lower.)
If pressure of –755mmHg or lower can not
be achieved even after vacuuming of 2
hours, repeat step
w
vacuum-breaking and
e
vacuum-dehydrating.
r
Vacuum holding test ..... 1 hour
t
Additional charge of refrigerant
Note: Make sure to use nitrogen gas for
vacuum-breaking. (If any oxygen gas is
used, it may explode.)
Positive
pressure
Atmospheric
pressure
Vaccume
Time chart of normal vacuum-dehydrating
+0.5kg/cm
2
0kg/cm
2
–200mmHg
–400mmHg
–600mmHg
–700mmHg
–755mmHg
Vacuum-dehydrating Vaccum
leaving
test
–760mmHg
(2 hours) (1 hours)
Totally 3 hours
Charge of
refrigerant
Addtional
pressure
Atmospheric
pressure
Vacuum
Time chart of special vacuum-dehydrating
+0.5kg/cm
2
0kg/cm
2
–200mmHg
–400mmHg
–600mmHg
–700mmHg
–755
mmHg
–755
mmHg
Vacuum-dehydrating
2 hours
Vacuum-breaking
Vacuum-dehydrating
1 hour
Vacuum-holding
test 1 hour
Charge of refrigerant
–760mmHg
Totally 4 hours
(1mmHg=0.0013kg/cm
2
=0.133Kpa)
w
Vacuum holding test
Hold the system at a pressure of
–755mmHg or lower for 1 hour or longer,
and confirm that the vacuum reading does
not rise on the vacuum gauge. If it rises,
moisture or leakage may exist in the
system. However, take care not to leak air
from the gauge manifold. If air enters, it is
recommended to use the cupper tube
directly instead of gauge manifold.
e
Charging of refrigerant
After the vacuum-holding test, make the
circuit vacuous again for approx. 10
minutes. Then, charge the specified
amount of refrigerant through the service
port on the liquid line using the charging
cylinder.
[Special vacuum-dehydrating]
This method is that the vacuum-breaking
process with nitrogen gas is integrated
one time or more in the same way as the
normal vacuum-dehydrating process.
Same as normal
vacuum-
dehydrating
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04̲LXE10E100以降(08-26)̲E.qx 08.8.27 5:04 PM ページ 4-26
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