Metrohm 781 pH/Ion Meter - Manual (Page 66)

6.2 pH measurement (pH mode)
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780/781 pH/Ion Meter, Manual
6.2 pH measurement (pH mode)
6.2.1 Measuring parameters
PARAMETER pH
├
measuring parameters
: ├
electr.id
├
drift pH
├
temperature*
├
method
├
delta measurement
└
stirrer
(* only appears if no temperature sensor is connected)
The measuring parameters describe the settings which are of direct
importance for the measurement.
electr.id: 12 ASCII characters
You can assign any name you like to the connected pH electrode. Dur-
ing a calibration the resulting calibration data will be assigned to this
entered electrode Id and stored. The electrode Id will then be included
in the report header for the output of measured values.
In this way you can enter several electrode Ids. This allows you to
switch between various pH electrodes with their associated calibration
data. However, a requirement is that each new electrode Id is linked
with a new calibration. Then you can use <SELECT> under the meas-
uring parameter Electr.Id to select one of the stored electrode Ids.
In order to delete an electrode Id and its linked calibration data this
must be reset under <CAL.DATA> ( Reset cal. , see Section 7.1.1).
drift pH 0.001...0.050...9.999/min, OFF
A measuring signal which changes as a function of time is regarded as
being sufficiently constant when its drift drops below the value defined
here. This can be used as criterion for the pH/Ion Meter if a displayed
measured value is to be stored or documented by printing a report (see
print criterion and storage criterion in Section 5.2 and Section 5.3).
Please note that for a drift-controlled measured value recording this drift
parameter must not be set to ' OFF ', as otherwise no result will be ex-
ported.
If the drift condition is not fulfilled then this is indicated by two constant-
ly blinking triangles in the display.
An active drift control increases the reproducibility of the measurements
as a constant condition is used to define the measured result. A smaller
value for the measuring parameter Drift pH requires a more stable
measuring signal than a larger one. The set measuring parameter is al-
so proportional to the measuring uncertainty of the measured value ob-
tained.