Xylem ProLab 4000 MULTIPARAMETER BENCHTOP METER - Manual (Page 190)

What to do if... ProLab 4000
190 ba75646e02 01/2010
No stable measured
value
Obviously incorrect
measured values
– Electrode broken – Replace the electrode
Buffer solutions:
– Incorrect buffer solutions – Select the suitable buffer set
for the buffers used
or
– Replace the buffer solutions
– Buffer solutions too old – Use only once.
Note the shelf life
– Buffer solutions depleted – Replace the buffer solutions
Cause Remedy
Cause Remedy
pH electrode:
– Diaphragm contaminated – Clean diaphragm
– Membrane contaminated – Clean membrane
Test sample:
– pH value not stable – Measure with air excluded if
necessary
– Temperature not stable – Adjust temperature if neces-
sary
Electrode + test sample:
– Conductivity too low – Use a suitable electrode
– Temperature too high – Use a suitable electrode
– Organic liquids – Use a suitable electrode
Cause Remedy
pH electrode:
– Not connected – Connect the electrode
– Cable broken – Replace the electrode
– pH electrode unsuitable – Use a suitable electrode
– Temperature difference
between buffer and test sam-
ple too high
– Adjust temperature of buffer
or sample solutions