IM 12B03D02-01E
6-3
6
.
Maintenance
6.3 Sensor Replacement
Since a pH sensor undergoes chemical changes with time, its performance
deteriorates gradually. Under normal operating conditions a sensor can be used for
one or two years. Sensor deterioration, however, speeds up depending on the nature
of a sample solution, e.g., a high temperature solution. Storage conditions also affect
the sensor life.
If
or
appears while calibration is being performed with a sensor for
which
is displayed, replace the sensor.
6.4 Rehydrating the Glass Electrode
A dry glass electrode gives fluctuating pH readings. If a glass electrode has dried up,
soak it in water (tap water) for 1 to 2 hours or longer to rehydrate. The sensor will give
stable pH readings.
6.5 Point to note when performing calibration or
measurement
When the internal electrode (Ag / AgCl) of the glass electrode is exposed to sunlight,
the electromotive force changes due to the influence of ultraviolet rays. In this case,
the pH value may be displayed higher than the actual pH value.
When calibrating the pH sensor and measuring the process solution, keep the glass
electrodes out of the sunlight.
