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15.1.1.3
pH sensor calibration (CAL) with an external sample (1-point)
Calibrating the controller diaLog DACb
CAL pH
Buffer 1:
Buffer 2:
Calibr.param. for 25 °C
Slope
% Slope
Asymmetry
Zero point
Accept with <CAL>
Fig. 40: Display of the calibration result
16.
Incorrect calibration
An error message appears if the result of the
calibration lies outside the specified tolerance
limits. In this case the current calibration is
not carried over.
Check the prerequisites for calibration and
eliminate the error. Then repeat calibration.
Cleaning and care of pH and ORP sensors
Please note the separate instructions sup‐
plied with the pH and ORP sensors for
cleaning and care of pH and ORP sensors.
After cleaning, the sensor must be condi‐
tioned in 3-molar potassium chloride solution
for 60 minutes before it can be reused for
calibration.
Carry over the result of the calibration into the controller
memory by pressing
ð The controller shows the continuous display again and
operates with the results of the calibration.
Measuring and control behaviour of the controller
during calibration
During calibration the actuating outputs are deacti‐
vated. Exception: a basic load or a manual control
variable has been set. This remains active. The
measured value output [standard signal output mA]
is frozen, corresponding to its settings in the mA
output menu.
When calibration/testing has been completed suc‐
cessfully, all of the error checks relating to the
measured value are restarted. The controller saves
all the determined data for zero point and slope
upon a successful calibration.
.
A1019
79
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