KNF SC 920 G Mode D'emploi page 58

Design and Function
Gas ballast
14 Translation of original Operating Instructions, English, KNF 334631-334633 07/21
Manual process control

(active control of the distillation using the setpoint pressure)
In order to change to another operating mode, the process is first
stopped and then restarted in the new operating mode.
The gas ballast switch (Fig. 2/5) can be used to open and close the
gas ballast valve on the vacuum pump system's pump (see
Chapter 5.5).
Vacuum Pump System SC 920G