Operation
6.2
Operating modes of the Controller
Setting to different operating modes
(see chapter 6.4.2)
Manual mode
Mode 1
Lowering the working pressure until the set pressure has been attained and held constant.
After switching on the power supply to the vacuum pump and controller, and selecting mode 1, the
process is started by pressing the start button. The pressure is reduced to the set pressure value
PS
(mbar)
1)
, see Setting control parameters.
In this way, the pressure is held constant by two defined threshold values (set value, hysteresis). This
operating mode exemplifies the classical 2-point control. This control procedure is repeated until the
operator terminates operation (
STOP
key). The receptacle may be ventilated by pressing the
AIR
key.
The set value may also be changed during operation in manual mode by means of (
↑
,
↓
). This set
value is not stored, so the set value present at program start is retained.
(see chapter 6.2.5)
"ecoflex" pump models work directly at the set pressure value.
Manual mode with settable pressure reduction
Mode 2
As in operating mode 1, but with an additional function for adapting the evacuation process to
processes in which the boiling point shifts (reduction of the concentration of the volatile com-
ponent).
After attaining the set pressure value
PS
, there is a further pressure reduction corresponding to the
set pressure value
PL
(1...1000 mbar) and a time
tL
(1...240 min)
2)
which has to be defined previ-
ously. The maximum rate of change of pressure is limited to 1 mbar/s.
Mode 5
Automatic operation
Lowering the working pressure until a boiling point is found automatically (also with mixtures).
In the automatic operating modes, the controller continuously checks the course of the pumping out
curve (pressure change per unit time). It interprets significant deviations in the slope as the start of
vapour formation and defines this pressure point as a set value. That is, the controller treats the value
found in this way from now on in the same way as the set value in the previous modes. The sensitivity
of the controller can be set with parameter
PA
(a higher
PA
value for volatile substances and a lower
PA
value for non-volatile substances, (see Setting control parameters)). After finding the pressure
point, the controller carries on working in mode 1.
In the case of certain solvent mixtures or deeply cooled condensates, the optimal boiling point is not
always found. In such cases, the distillation process may be further optimised by repeating with chan-
ged
PA
values. Maximum distillation speed can be achieved in this way, taking into account the cooler
capacity and the stability of the vaporization process (no frothing of the distillate).
Automatic operation with settable pressure reduction
Mode 6
As operating mode 5, and after the boiling point has been found, in order to get a further low-
ering of the working pressure corresponding to the set pressure value PL (mbar) and tL
(min)
2)
.
CAUTION !
The vacuum controller is released for the application of modes 1, 2, 5 and 6.
The mode required is selected according to the work task and the connected periph-
eral equipment.
1) Corresponding to the set unit of measurement: mbar, Torr, psi
2) tL is displayed on the control panel in minutes, and in the "ILMVAC-Control" program in seconds.
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