Metrohm 867 pH Module - Manual (Page 36)

5.1 General
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867 pH Module
5 Troubleshooting
5.1 General
Problem Cause Remedy
The measured value
is evidently wrong. The calibration is wrong. ￭ Check the calibration and repeat, if neces-
sary.
￭ Check the buffer or standard solutions and
repeat the calibration, if necessary.
The manual temperature
input is wrong. Enter the correct measuring temperature.
The pH or ISE membrane or
the diaphragm is contami-
nated. Clean the membrane or the diaphragm.
The electrolyte or the mea-
suring chain is overaged. Replace the electrolyte or the measuring chain.
The measuring chain is
defective. Replace the measuring chain.
No or heavily fluctu-
ating measuring sig-
nal. The measuring chain is not
connected. Connect the measuring chain.
Air is trapped in or in front
of the diaphragm. Remove the air.
The measuring chain is
defective. Replace the measuring chain.
The measured value
remains unstable
and does not fulfil
the drift criterion. The pH or ISE membrane or
the diaphragm is contami-
nated. Clean the membrane or the diaphragm.
The pH value or the tem-
perature of the measuring
solution is not stable. ￭ Measure under exclusion of air.
￭ Control the temperature of the measuring
solution.
Unsuitable measuring
chain. The conductivity is
too low or an organic solu-
tion is present. Use a suitable measuring chain.
The measuring chain is not
connected. Connect the measuring chain.