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Air tightness test and vacuum drying
Vacuum drying pipes and indoor units
f Use tools for R-410A to prevent the inflow of foreign substances and resist against the internal pressure.
f Use vacuum pump that allows vacuuming under -100.7kPa (5 Torr).
f Use the vacuum pump with the check valve to prevent pump oil from flowing backward while the vacuum pump is
stopped.
f Completely close the liquid·gas side service valve of the outdoor unit.
Connect the manifold gauge to the liquid side pipe
and gas side pipe (when installing outdoor units in
module).
When installing outdoor units in module, connect the manifold gauge to
liquid side pipe and the gas side pipe.
Perform vacuum drying of the liquid side pipe and
gas side pipe (when installing outdoor units in
module) using a vacuum pump.
Make sure that check valve is installed to prevent pump oil from flowing
into the pipe.
While the vacuum gauge pressure is less than
-100.7kPa (5Torr), perform the vacuum drying for
more than 1 hour and close the valve.
Vacuum pressure must be checked with the vacuum gauge.
After vacuum pump stops, check whether the
pressure is maintained within -100.7kPa (5Torr) for
an hour.
Charge additional refrigerant to the pipe
No
Ye s
Perform vacuum drying again
Check for gas leakage
Vacuum destruction
t Apply nitrogen gas to the pipe at pressure of
0.05Mpa(7.25psi).
Ye sNo
Over -100.7kPa (5Torr)
Pressure increase
❋ If the pressure rises in an hour, either water is remaining inside the pipe or there is a leakage.
❋ When the ambient temperature of vacuuming pipe is low (less than 0°C (32°F)), moisture might remain within the pipe.
Therefore, pay special attention to the pipe sealing in the winter.
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