wtw inoLab pH/ION Level 2 Operating Manual page 64

What to do if...
No stable
measured value
Sensor symbol
flashes
148
Buffer solutions:
– Incorrect buffer solutions
– Buffer solutions too old
– Buffer solutions depleted
Cause
pH electrode:
– Diaphragm contaminated
– Membrane contaminated
Sample:
– pH value not stable
– Temperature not stable
Electrode + sample:
– Conductivity too low
– Temperature too high
– Organic liquids
Cause
– Calibrating interval
expired
– Change calibration
procedure
– Only use once.
Note the shelf life
– Change solutions
Remedy
– Clean diaphragm
– Clean membrane
– Measure with air
excluded if necessary
– Adjust temperature if
necessary
– Use suitable electrode
– Use suitable electrode
– Use suitable electrode
Remedy
– Newly calibrate
measuring system