Troubleshooting
Page
71
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Signs of a defective electrode
The following signs indicate an electrode is reaching the end of its lifetime. The
electrode must be replaced whenever one of the following signs are observed:
■
The pH/Temperature sensor is difficult to calibrate. Storing a calibration point
should take max. 180 seconds. The electrode must be replaced if a longer time is
required.
■
The pH/Temperature sensor was calibrated successfully, but the output drifts
within 15 minutes after the calibration. To test drift, immerse the sensor in e.g.
clean tap water – note the initial displayed pH value – leave the sensor in the water
for 15 minutes - then note the displayed value after 15 minutes.
Calculate drift:
Drift = “Initial value” ÷ “15-minute value”
Max drift allowed is +/- 0.2 pH units
■
The pH/Temperature sensor gives a fixed output of around pH 7.
■
The pH/Temperature sensor gives no output.
■
The glass tip of the electrode is damaged.
■
Water has entered the electrical connection of the electrode.
■
If the pH sensor flashes every second, the calibration is not accepted.
The electrode can easily be changed. To change the electrode, follow the
maintenance instruction MI6100-0007.
NOTE
It is recommended that an electrode is kept in stock as a spare part.
