Xylem SL Analytics Lab 865 Operating Manual page 56

What to do if...
No stable measured
value
Obviously incorrect
measured values
56
Cause
pH electrode:
– Junction contaminated
– Membrane contaminated
Test sample:
– pH value not stable
– Temperature not stable
Electrode + test sample:
– Conductivity too low
– Temperature too high
– Organic liquids
Cause
pH electrode:
– pH electrode unsuitable
– Temperature difference between
buffer and test sample too great
– Measurement procedure not suit-
able
Remedy
– Clean junction
– Clean membrane
– Measure with air excluded if
necessary
– Temper if necessary
– Use suitable electrode
– Use suitable electrode
– Use suitable electrode
Remedy
– Use suitable electrode
– Adjust temperature of buffer or
sample solutions
– Follow special procedure
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Lab 865
12/2017