IKA VC 10 Mode D'emploi page 32

Two-position control
A vacuum is made in the glassware with the help of a vacuum
pump. The vacuum pump operates at constant speed which gene-
rally cannot be adjusted. Once the target value setting is reached,
the integrated vacuum valve interrupts the suction line. If additi-
onal switching on and off of the vacuum pump is desired, please
use the VC 2.4 pump control (accessory).
The device will fall slightly short of the target value setting due to
the time difference in the millisecond range with the vacuum va-
lue, the target value comparison and the switching of the vacuum
valve. Natural leakage from the apparatus now causes another
increase in the pressure value of the system, which in turn is de-
tected by the integrated pressure sensor.
If the target value is exceeded, the vacuum valve is reopened and
the vacuum pump in operation lowers the pressure. The pressure
curve shown on the display fluctuates around the set target value.
The pressure difference between activating/deactivating the valve
can be set using the vacuum hysteresis value.
The quality of the control depends on the suction power of the
Analogue speed control
Imprecision of the two-position control is avoided by using the
analogue speed control.
With this kind of control, the speed of the pump, and therefo-
re its suction power, is reduced the closer the measured pressure
reaches the target value. Once the target value is reached, the
pump only operates according to the leakage rate of the system.
This type of control offers quieter operation, more exact vacuum
control and a long service life of movable pump parts.
Automatic boiling point recognition is possible with this type of
control, i.e. the system reaches and keeps the solvent at its boiling
point in automatic mode.
Analogue speed control with the IKA
vacuum pump:
The MVP 10 digital membrane vacuum pump is automatically
detected as soon as the connection cable is plugged into both
devices. The analogue speed control is enabled, the two-position
control is disabled and cannot be selected.
Menu items such as automatic boiling point recognition, program-
med pressure-time curves or programs from the solvent library can
be used.
Refer to the operating instructions for the MVP 10 digital vacuum
pump.
Schematic view of speed-vacuum control
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MVP 10 digital membrane
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pump (rotation speed), the tightness of the system and signal de-
lay time of the electronics used.
Automatic boiling point recognition is not possible when using
two-position control.
Schematic view of a two-position vacuum control
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An external temperature sensor can be connected to the "PT1000"
temperature sensor interface. When the menu view is enabled,
the temperature value is shown in the display.
Time sequences can be controlled using a timer.
The operating modes A, B, C and D have preset access options for
adjusting and saving target values.
Display settings can be changed using the "Display" menu item.
Access to the device can be restricted by setting up a password in
the "Security" menu item.
Common settings such as language, pressure and temperature
units can be set via the "Settings" menu item. The display back-
ground can also be changed from black to white as well as bright-
ness settings adjusted.
The integrated solvent library calculates the theoretical boiling
point at a specified steam temperature value, or vice versa.
The upper and lower limits or the switching points of the vacuum
control can be set in the submenu items "Limit values" and "Hys-
teresis".
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