138-EN
137-EN
– 69 –
Vacuum drying
• Be sure to use a vacuum pump equipped with the counter-
fl
ow prevention function so that oil in the pump will
not
fl
ow back into piping for air conditioners. (If oil in the vacuum pump enters in the air conditioner with R410A
refrigerant, a problem may be caused in the refrigerating cycle.)
After
fi
nishing the airtight test and discharging nitrogen gas, connect the gauge manifold to the service ports of the
suction gas side, discharge gas side, liquid side and balance pipe side and connect a vacuum pump as shown
in the
fi
gure below. Be sure to perform vacuuming for the suction gas side, discharge gas side, liquid side and
balance pipe side.
P
V
L
V
H
Packed valve details
To gauge
manifold
Liquid-side
service port
Liquid-side
valve
Piping at site
To
outdoor
unit
Piping
at site
To outdoor unit
Piping
at site
Connected to
other follower
units
Main
pipe
Connected to
indoor unit
Low pressure
gauge
High pressure
gauge
Gauge
manifold
Vacuum
pump
Balanced pipe side valve fully
closed
Liquid side valve fully
closed
Discharge gas side valve
fully closed
Fully
closed
Fully
closed
Fully
closed
Brazed
Suction gas side valve
fully closed
Header outdoor unit
Service port
Service port
Service port
Piping
at site
Ball valve of suction gas side
Service port of suction gas side
Service port
of discharge
gas side
Ball valve of
discharge
gas side
To outdoor
unit
To
gauge
manifold
Service
port
of balance
pipe side
Packed
valve
of balance
pipe side
To
outdoor
unit
Service port
• Use a vacuum pump with a high vacuuming degree [-100.7kPa (5Torr, -755mmHg)] and large exhaust gas
amount (40L/minute or larger).
• Perform vacuuming for 2 or 3 hours, though the time differs depending on the pipe length. Check that all the
valves at the suction gas side, discharge gas side, liquid side and balance pipe side are fully closed.
• If the pressure does not reach -100.7kPa or less even after vacuuming for over 2 hours, continue vacuuming for
1 hour or more. If the pressure does not reach -100.7kPa after 3 hours of vacuuming, stop vacuuming and check
for air leakage.
• If the pressure reaches -100.7kPa or less after vacuuming for 2 hours or more, close the valves VL and VH on
the gauge manifold fully and stop the vacuum pump. Leave it as it is for 1 hour to con
fi
rm that the vacuuming
degree does not change.
If the degree of vacuum loss is large, moisture may remain in the pipes. In that case, inject dry nitrogen gas and
apply pressure to 0.05MPa and perform vacuuming again.
• After
fi
nishing the above procedure of vacuuming, exchange the vacuum pump with a refrigerant canister and
advance to the additional charging of refrigerant.
Able to detect a serious leakage
1. Apply pressure 0.3MPa (3.0kg/cm
2
G) for 5 minutes or more.
2. Apply pressure 1.5MPa (15kg/cm
2
G) for 5 minutes or more.
Available to detect slow leakage
3. Apply pressure 3.73MPa (38kg/cm
2
G) for approx. 24 hours.
• If there is no pressure decrease after 24 hours, the test is passed.
NOTE
However, if the environmental temperature changes from the moment of applying pressure to 24 hours after that,
the pressure will change by about 0.01MPa (0.1kg/cm
2
G) per 1°C. Consider the pressure change when checking
the test result.
REQUIREMENT
When pressure decrease is detected in steps 1-3, check the leakage at the connecting points.
Check the leakage using a foaming agent or other measures and seal the leak with re-brazing,
fl
are retightening
or other methods. After sealing, execute an airtight test again.
1117701001-EN.indd 69
1117701001-EN.indd 69
2/26/2559 BE 11:48 AM
2/26/2559 BE 11:48 AM
