VACUUBRAND VNC 2 - Manual (Page 25)

Documents are only to be used and distributed completely and unchanged. It is strictly the users´ responsibility to check carefully
the validity of this document with respect to his product. Manual-no.: 999161 / 27/03/2012
page 25 of 45
Temporary switching from ”vacuum control” to ”continuous pumping”:
➨ Keep key t pressed for more than 2s (decrease of preset pressure), then press key ”Enter” addition-
ally. The controller switches to ”continuous pumping”. No change of the basic mode of the controller
takes place. Once the pump down is stopped (”Esc”), the controller VNC 2 switches back to the mode
”vacuum control”.
Temporary switching from ”continuous pumping” to ”vacuum control”
➨
If the key ”Enter” is pressed while pumping down, the pumping down is interrupted. Pressing addi-
tionally the key t results in switching to the mode ”vacuum control”. The actual pressure is stored as
preset pressure. No change of the basic mode takes place. Once the regulation is stopped (”Esc”),
the controller switches back to the mode ”Continuous pumping”.
☞ Tip for distillation: Temporary switching to continuous pumping enables an user friendly semiauto-
matic control of a distillation. Pump down (”Continuous pumping”) until the boiling point is reached,
then press ”Enter” and key t. The controller keeps the reached pressure value (boiling pressure)
constant. Further pumping down by firstly pressing ”Esc” (vacuum control is stopped) and then press-
ing either ”Enter” (pump down) or key t.
☞ Tip for filtration: Adjust preset pressure to a value well above the boiling pressure of the solvent
(e.g. water: p Set » 100 mbar). Set ”Limit” to e.g. 500 mbar. Once the filtration has finished, the
pressure increases, and the pump will be switched off.
Adapting parameters during the regulation:
• Interruption: Press key ”Enter”, the control stops; after releasing the key, the control continues. Dur-
ing the interruption the preset pressure can be set to the actual pressure by pressing the key t. By
pressing the key s, the hysteresis can be set to the actual pressure. Performing both tasks in a row
results in hysteresis 0 = Auto, because the preset pressure as well as the hysteresis are set to the
same pressure value.
• Decrease of preset pressure: Keep key t pressed for more than 2s (pump is running at set
speed).
• Increase of preset pressure: Keep key s pressed for more than 2s (venting valve opens).