Metrohm 840 PC Control 5.0 / Touch Control - Manual (Page 275)

4 Parameters
PC Control / Touch Control
263
4.8 Calibrating conductivity measuring cells (CAL
Cond)
The cell constant of a conductivity measuring cell can be determined
with the CAL Cond command.
Under Calibration parameters you can edit the parameters for the
calibration sequence.
• Signal drift (d): Drift, i.e. the alteration in the measured value per
minute that has to be reached for measured value acceptance. off
means that the measured value acceptance takes place when the
maximum waiting time has elapsed. This may be advisable if the
measuring cell has a very slow response.
• Waiting time min. (d): The measured value is not accepted until
the minimum waiting time has elapsed, even if the measured value
drift has already been reached. The minimum waiting time is only
important for drift-controlled measurements.
• Waiting time max. (d): If the signal drift is switched off or has not
yet been reached then the measured value will be accepted after
the maximum waiting time has elapsed.
• Measuring temp. (d): Manually entered measuring temperature. If a
temperature sensor is connected and temperature measurement is
set to automatic or continuous under Sensor (see Section 4.1.5)
then the temperature will be measured. If off is defined then the
temperature is requested after the start.
Under Standard the characteristics of the calibration standard are en-
tered. These values are proposed in the query after the start of the
method.
• Request at calibration start: If this parameter is switched on
then you are requested – after the start of the method – to enter the
following parameters.
• Conductivity std. (d): Enter the conductivity of the calibration
standard used.
• Reference temp. std. (d): Enter the reference temperature at
which the calibration standard has the conductivity entered above.
• Temp. coefficient (d): Enter the temperature coefficient corre-
sponding to the above reference temperature.
Under Stirrer control you can edit the parameters for controlling the
stirrer during the calibration. Take care that you have selected a stirrer
under Edit command/Stirrer.
• Stir solution during measurement (d): Automatically switches
the stirrer on/off at the start and the end of the measurement.
• Stir before meas. (d): If stirring is switched off during the meas-
urement, the solution can be stirred before the measurement. Enter
the corresponding time here.
• Pause before meas. (d): If stirring is carried out before the meas-
urement, a pause interval can be entered here. No stirring or meas-
uring occurs during this time.