12
BÜCHI
Vacuum Controller
B-720
5 Operation
5.4 Hold state
After distillation is started, you can use the arrow keys to
intervene in the automatic control sequence at any time. Pressing
«UP» causes an immediate increase of the system pressure
(the system is aerated), pressing «DOWN» decreases the system
pressure.
Action
Display
Function
Hold state
«ON» switch
957
• The unit is switched on.
(current system pressure)
«START»
957
• Distillation is started.
147
(current system pressure)
«UP»
387
• The evacuation process is interrupted and the LED of «START»
(current system pressure)
flashes.
• Hold state.
Keep key depressed
• The system pressure is adapted as long as the key is kept
depressed, i.e. while «DOWN» is pressed, the pressure will
be lowered continually; press «UP» and the ventilation valve
will be opened.
• After you release «UP» or «DOWN», the new pressure will be
controlled with the saved hysteresis.
• Press briefly on «START» to continue the function that was
active before the interruption.
Table 5: Hold state
