Stratos Multi E401N
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6.4 Process Variable Conductivity (Contacting) Calibration/Adjustment
Note:
During calibration, the function check (HOLD) operating state is active for each of the calibrated
measuring channels. The outputs respond as configured.
• Calibration: Detect deviations without readjustment of calibration data
• Adjustment: Detect deviations with readjustment of calibration data
NOTICE!
When using analog sensors, adjustment is required following sensor replacement.
Explanations Regarding Calibration/Adjustment with 2-/4-Electrode Sensors
Each conductivity sensor has an individual cell constant. Depending on the sensor design, the cell
constant may vary over a wide range. Because the conductivity value is calculated from the measured
conductance and the cell constant, the device must know the cell constant. During calibration or
sensor adjustment, either the known (printed) cell constant of the used conductivity sensor is entered
in the device, or it is determined automatically by measuring a calibration solution with known
conductivity.
Notes on Calibration
• Use only fresh calibration solutions.
• The used calibration solution must be configured.
• The accuracy of the calibration is crucially dependent on a precise acquisition of the calibration so-
lution temperature. On the basis of the measured or entered temperature, Stratos Multi calculates
the setpoint of the calibration solution from a stored table.
• Note the response time of the temperature probe.
• To determine the exact cell constant, wait for temperature equalization of the temperature probe
and calibration solution before calibration.
Since the cell constant is subject to production-related fluctuations, it is recommended that the
removed sensor be calibrated with a calibration solution (e.g., saturated NaCl). The cell constants of
the sensors are dependent on the installation geometry – especially in the case of fringe-field sensors:
• If the sensor is installed in a free space (minimum distances exceeded), the cell constant specified
in the specifications can be entered directly.
Calibration mode
: “Data Entry”.
• If the installation space is tight (minimum distances are not reached), the sensor must be adjusted
in its installed state, as the resulting cell constant has changed.
Calibration mode
: “Product Calibration”.
6.4.1 Temperature Compensation during Calibration
The conductivity value of the calibration solution is temperature-dependent. During calibration,
the temperature of the calibration solution must therefore be known so that the actual value can be
obtained from the conductivity table.
Automatic Temperature Compensation
During automatic logging of the calibration temperature, Stratos Multi measures the temperature of
the calibration solution using the temperature probe integrated in the Memosens sensor.
If the sensor does not have an integrated temperature probe:
• Connect an external temperature probe and select it in the Parameter Setting menu.
pH Analog Wiring Examples, p. 168
• Set the manual temperature for calibration.
