VDL (E3) 09/2019 Page 114/234
11.6 Drying monitoring
Pressure
Time
Figure 25: Schematic timing of the drying process and drying monitoring
Procedure:
• Enter the temperature set-point.
The previously entered pressure setpoint is not used with this function. It remains saved.
The drying monitoring uses a fixed minimum pressure setpoint.
• Start the drying monitoring: the vacuum pump is activated, the evacuation valve opens.
Starting from ambient pressure, the pressure starts to decrease.
• Depending on the vapor pressure of the solvent, a plateau phase is then reached
during which the
solvent vaporizes. The pressure remains almost constant.
• After the solvent is completely evaporated, drying is complete.
The pressure starts to decrease
again
Without drying monitoring the pressure would now continue to decrease
, until the maximum final
vacuum is reached.
• The drying monitoring recognizes this second pressure drop. It turns off the pressure control. The
chamber will the be ventilated automatically
.
Prior to starting a new drying process, the pressure control must be activated again (chap. 11.4).
Note: If the drying monitoring is aborted during phase
or , the controller will take the current actual
pressure value as the pressure setpoint. This overwrites the previously entered pressure setpoint. It can
be changed manually at any time.
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