SCHOTT Lab 850 - Unstable Readings and Conditions

What to do if... Lab 850
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ba75890e01 11/2009
No stable measured
value
CalClock flashes
Display,
LoBat
– Incorrect buffer solutions – Change calibration
procedure
– Buffer solutions too old – Use only once.
Note the shelf life
– Buffer solutions depleted – Change solutions
Cause Remedy
Cause Remedy
pH electrode:
– Junction contaminated – Clean junction
– Membrane contaminated – Clean membrane
Test sample:
– pH value not stable – Measure with air excluded if
necessary
– Temperature not stable – Adjust temperature if
necessary
Electrode + test sample:
– Conductivity too low – Use a suitable electrode
– Temperature too high
– Organic liquids
Cause Remedy
– Calibration interval expired – Recalibrate the measuring
system
Cause Remedy
– Batteries almost empty – Replace the batteries (see
page 53)