Stirring Bar Breakaway Monitoring; Setting The Intermittent Mode And The Stirring Bar Breakaway Monitoring Fonction; Measurement Of Viscosity Trend - IKA IKAMAG RET control-visc C Betriebsanleitung

12.2

Stirring bar breakaway monitoring

When the unit is switched on, the stirring bar breakaway moni-
toring function is displayed (On/OFF SAFE Rpm).
Stirring bar breakaway can occur with any magnetic stirrer.
Breakaway can occur when stirring at high speeds or when
large stirring bars are being driven at speeds close to the mag-
netically transmissible maximum torque and there are variati-
ons in medium viscosity or controller fluctuations.
On the RET control-visc /C you can select the stirring bar brea-
kaway monitoring function which operates in the setpoint
speed range between 300 and 1500 rpm.
When stirring bar breakaway is detected, stirring is stopped
momentarily to enable the stirring bar to be picked up. After
this, stirring starts again and ramps up to the setpoint speed (<
flashes). If a further stirring bar breakaway occurs within the
next 3 minutes of stirring at a constant setpoint speed, the stir-
ring bar will be picked up again and stirring will restart but this
time at the setpoint speed reduced by 100 rpm The red
"Temp" LED flashes and the buzzer will sound for several
seconds. After the fourth stirring bar breakaway – with less
than 3 minutes normal stirring – the error message ER 41 will
be displayed (the motor will continue to run and the heating is
switched off) the red "Temp" LED will flash and the buzzer will
sound. When further stirring bar breakaways occur, the speed
will be reduced each time in 100 rpm steps until the minimum
of 200 rpm is reached. The speed is no longer displayed. In this
case you should select new test conditions.
IMPORTANT:
You must calibrate and test the stirring bar breakaway
monitoring function for your particular configuration
taking into account the stirring bars, speed, vessel and
medium you are using.
The reliability of stirring bar breakaway monitoring increases as
the transmitted torque increases.
In a glass beaker filled with water, the function will detect the
breakaway of stirring bars longer than 50 mm (d=8 mm) in the
speed range from 300 to 1500 rpm. Increasing the stirring bar
RETCV_0107
length, the stirring bar surface area (e.g. TRIKA coated bars) or
increasing the speed will increase the torque transmitted.
The stirring bar breakaway monitoring function will not
operate if the stirring bar breaks away while the stirring is
still ramping up to the setpoint speed.
12.3 Setting the intermittent mode and the stir-
ring bar breakaway monitoring function
• Switch off the unit at the main ON/OFF switch.
• Hold the "Mot" and the "Mode" membrane buttons pres-
sed down and switch on the main ON/OFF switch. After
approx. 5 seconds release the membrane buttons.
• After the display self-test (when all the LCD segments
flash), the message On or OFF IntErmit will be displayed.
• Press the "Mot" membrane button within the next 5
seconds to switch the intermittent mode ON or OFF as requi-
red.
• If you disable the intermittent mode by selecting OFF, the
message On or OFF Safe Rpm will be displayed.
• To switch the stirring bar monitoring function ON or OFF,
press the "Mot" membrane button within the next five
seconds.
IMPORTANT:
These changes will be stored to memory when the self-
test (SAFE H or SAFE P OK is displayed) has been com-ple-
ted.
12.4

Measurement of viscosity trend

This measurement is determined with the help of the control soft-
ware via the controlling variable given to the motor, and is shown
in percent in the digital display. The maximum controlling variable
(maximum torque of motor) is 100%.
The instruments are not designed for measuring the absolute vis-
cosity. Only the relative change in the product in relation to an initi-
al point determined by the user, is measured and displayed. As the
controlling variable is strongly dependent on the real speed, this
should not be changed during a measurement.
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