5
BÜCHI
Vacuum Controller
B-720
3 Function
3 Function
The B-720 keeps a selected level of vacuum constant. It
automatically compensates any loss of vacuum in the evacuated
system by re-adjusting the vacuum to the set pressure level. It
does so by actuating a two-way valve in the vacuum line or by
directly switching the vacuum source on and off.
Solvent can be condensed with hight efficiency if the optimum
vacuum level is selected for the specific solvent. This results in
an immense reduction of solvent through the vacuum pump or
in a laboratory’s waste water.
You can also use the B-720 to control the flow of cooling water
during distillation. This is done by actuating a cooling water valve.
Water savings of up to 95 % are possible this way.
All B-720 models are delivered as standard with an aeration
valve, also used for purging with inert gas, a cross clamp for
mounting on a stand, and a GL14 hose connector for connecting
the vacuum hose.
Figure 4: The keypad on the B-720
3.1 Functions of the various keys
«P»
You can set the desired value of your choice with
the arrow keys. If no key is pressed within 3 seconds,
the display will switch to its initial state and the
setdesired value will be saved automatically.
«
욼
P»
You can set the desired hysteresis in mbar or Torr
with the arrow keys. If no key is pressed within 3
seconds, the display will switch to its initial state
and the setdesired value will be saved automatically.
«UP»
Press this key to increase the desired value.
«DOWN»
Reduces the pressure or hysteresis during distil-
lation.
«mbar/Torr» Switches the LED display from mbar / hPa to Torr /
mm Hg.
«START»
Starts the evacuation process.
«STOP»
Stops the vacuum process. The system is ventilated,
but the cooling water valve does not close until 5
minutes later. Press twice for the cooling water to
be switched off immediately.