Metrohm 867 pH Module - Manual (Page 37)

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5 Troubleshooting
867 pH Module
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Problem Cause Remedy
The measuring chain is
defective. Replace the measuring chain.
Sluggish measured
value setting. The pH or ISE membrane or
the diaphragm is contami-
nated. Clean the membrane or the diaphragm.
Insufficient slope
during calibration. The pH or ISE membrane or
the diaphragm is contami-
nated. Clean the membrane or the diaphragm.
No hydrated layer is pres-
ent on the glass membrane
after measurements in
water-free solutions. Between measurements, place separate elec-
trodes in distilled water and combined elec-
trodes in reference electrolyte.
The buffer or standard sol-
utions are old. Use fresh buffer or standard solutions.
The electrode is worn out. Replace the electrode.
The Delta U poten-
tial step set is not
achieved with 'auto'
standard addition. The streaming potential of
the indicator electrode or
reference electrode results
in a potential difference
between stirred addition
and non-stirred measure-
ment. ￭ Reduce the dosing rate.
￭ Increase the stirring rate.
￭ Increase Delta U.
￭ Touch Control:
Select Addition = auto dos.