IKA RET control-visc - Manual (Page 26)

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Stirring bar breakaway
If the device detects that a stirring bar has broken away, the
stirring function is interrupted temporarily in order to pick up
the bar. The system then returns to the previously set speed.
When the system detects a bar breakaway, this is indicated with
a special symbol ( instead of symbol 16). If another stirring
bar breakaway occurs within the next 3 minutes (as long as the
target speed has not been modified), once the bar is recovered
the system only goes up to a speed of 100 rpm. In the case of
4 consecutive stirring bar breakaways -with less than 3 minutes’
normal speed between them - the error message ER 41 is
displayed. The speed is reduced to 200 rpm and the heating is
switched off.
In such cases, the testing conditions will need to be reconsidered.
NOTE:
The user is responsible for ensuring the suitability/function
of the stirring bar breakaway monitoring for the current
conditions: stirring bar, speed, vessel, medium, etc.
Stirring bar breakaway monitoring does not work if the
stirring bar already breaks away before the system has
reached the set target speed!
The higher the torque to be transferred, the more safely the
stirring bar breakaway monitoring works.
In a glass beaker with water, the stirring bar breakaway for a
bar from 40 mm (d=8 mm) upwards can be seen from 300 -
1,200 rpm. Longer stirring bars, larger bar surface areas, e.g.
Trika, or higher speeds increase the torque to be transferred.
• Scroll to the “Stirring” icon
in the menu
• Open the submenu by
pressing the rotary knob (D)
• Open the “Stirring bar
breakaway” submenu and
confirm by pressing the
rotary knob (D)
• Acknowledge the informa-
tion screen displayed by
pressing the rotary knob (D)
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Intermittent mode
Intermittent mode consists of regular, cyclical interruption of
the stirring function. The run time and interval can both be set.
When switching on the device, the time for each is displayed if
intermittent mode is activated
• Scroll to the “Stirring” icon
in the menu
• Open the submenu by
pressing the rotary knob (D)
• Open the “Interval”
submenu and confirm by
pressing the rotary knob (D)
• Enter the run time and stop
time using the rotary knob
(D) and finally confirm the
two by pressing it again.
Torque trend measurement
The torque trend measurement is used to deduce the change in
viscosity of the reaction medium.
The devices are not designed to measure absolute viscosity. They
only measure and display the relative change in the viscosity of the
medium from a starting point specified by the user.
Once the speed of the motor and magnetic rod in the medium
have stabilised to the target speed, the viscosity measurement is
started at 100%.
Consequently, an increase in the measured torque trend is indicated
by a value > 100% and a reduction in values < 100%.
The value can always be reset to 100% by pressing the “Back” (F)
membrane key.
Note:
Torque trend measurement only works for a constant set
speed for the duration of the measurement.
As a result, intermittent mode cannot be used in
conjunction with torque trend measurement.