wtw MultiLine P4 Bedienungsanleitungen Seite 54

Other possible errors - pH measurement
System message
Voltage of pH
electrode not stable
Measured values
obviously wrong
54
Cause
pH electrode:
œ Diaphragm contaminated
œ Membrane contaminated
Sample solution:
œ pH value not stable
œ Temperature not stable
Electrode + sample solution:
œ Conductivity too low
œ High temperature
œ Organic fluids
pH electrode:
œ Unsuitable pH electrode
œ Temperature difference
between calibration and
sample solution too big
œ Interference voltages
œ Unsuitable measuring
procedure
Troubleshooting
Action
pH electrode:
Clean diaphragm
Clean membrane
Sample solution:
Measure in an airproof vessel
if necessary
Temper if necessary
Electrode + sample solution:
Use suitable pH electrode
Use suitable pH electrode
Use suitable pH electrode
pH electrode:
Select suitable pH electrode
Temper buffer or sample
solution
With grounded sample solution
do not use a grounded PC or
printer
Pay attention to special
procedures