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BÜCHI Vacuum Controller V-800/V-805
8.8 Automatic distillation (only with connected
auto sensor)
8.8.1 Preconditions for an automatic distillation
The automatic dual temperature sensor is based on a balance
adjustment of the temperature in the condenser with
consideration of the cooling material temperature. For trouble-
free distillation until dryness, the following conditions must exist:
• minimum solvent quantity 50 … 100 ml.
• Boiling point differences in the case of solvent mixtures is
not greater than 45…50°C. Greater differences lead to
back evaporation from the receiving flask and stopping of
the apparatus.
• Temperature difference between heating bath and cooling
35…45°C.
It is difficult to evaporate solvent mixtures with very large boiling
point and/or evaporation heat difference in automatic mode.
This includes many aqueous solvent mixtures.
You cannot add anything to the evaporating flask in the
automatic mode. To do this, the controller must be changed
into the manual mode, the material added to the evaporating
flask and then the apparatus must be changed back into the
automatic mode.
8.8.2 Performing automatic distillation
Choose the autodist function [MENU] ð [MODE] ð
[AUTODEST.] (if it is not already active). The display changes
to the READY state. You do not have to input any other
parameters.
Now, the controller is ready. Use [RUN] to start it.
[STOP] ends the distillation and ventilates the apparatus
(unless configured otherwise).
8 Operation V-805
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