Leave - Hitachi RCUE40AG2 Service Manual

Maintenance
Water evaporation>
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
CAUTION
If there is a possibility of dew condensation, vacuum (vacuuming time) should be
controlled more strictly since water does not evaporate easily and it is diffi cult to know
the degree of dew condensation. It is desirable to control the vacuum grade as a
–755~758 mmHg (5~2 Torr).

6.10.2. Leave


CAUTION
pag. 171
SMGB0003 rev.0 - 11/2006
In atmosphere pressure, water boils at 100°C, however, each time a pressure in
pipes reaches to a vacuum state, water boils at lower temperature than 100°C.
The lower this temperature is, the more water evaporates and vacuum drying is
kept.
After fi nishing vacuuming, manifold valve is closed and vacuum pump is
stopped, and then leave it for 1 hour to confi rm if a pressure measured by
vacuum gauge is not increased.
1. This process should be performed since air can be leaked due to the
negative pressure although air leakage is not confi rmed in air tight test.
2. In case of increasing pressure, it is possible that there is a slight
leakage in some positions. Perform air tight test again, and perform
vacuum drying again after repaired.
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