Calibration Of Ph Electrode - Burkert 8205 Manuel D'utilisation

4 OPERATION
PH TRANSMITTER 8205

4.2.2 Calibration of pH electrode

In order to obatain reliable measurements, it is necessary to perform regular clibrations of
the pH electrode.
1 or 2 measuring point calibration methods are available.
1 measuring point method: enables a quick control calibration with pH=7 buffer soluti-
on.
2 measuring points method: enables a precise calibration of zero and slope of the pH
electrode. 2 buffer solutions are required. The first solution is usually pH=7.
Use the second buffer solution as close as possible to the assumed final pH value. Before
each calibration, clean the electrode (see §5.2). The temperatures of the buffer solutions
must be equal. The pH transmitter must be calibrated regularly.
This maintenance procedure is very important to ensure a reliable control operation.
Calibartion of the electrode must be done with the temperature sensor. Please take into ac-
count the dependence in temperature of the buffer solution (especially by basic solutions).
This value is mentioned on the buffer bottles.
The frequency of calibrations depends upon the degree of contamination of the measuring
fluid: in normal conditions, calibration should be repeated once a week.
A "WARNING" message at the end of calibration points on a buffer solution error or
advanced ageing of the electrode; the message is displayed as soon as the electrode has
reached the half of its lifetime (i.e. a Span value between 50 and 53 mV/pH or between 63
and 65 mV/pH and an Offset value between -60 mV and -35 mV or between 35 mV and 60
mV). A change of electrode must be anticipated.
An "ERROR" message at the end of calibration points on that the electrode must be re-
placed. The message is displayed when the Span value is < 50 mV/pH or > 65 mV/pH and
the Offset value is < -60 mV or > 60 mV. The current calibration is not taken into account.
Calibrate the device with the new electrode.
The MANUAL option makes it possible to enter the Offset (OF=) and Span (SP=) values of
an electrode that has been calibrated with another Burkert pH transmitter.
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