Optex SE-pH-D Instruction Manual page 51

If the measurement result is poor as shown below, the calibration
has been completed. However, take appropriate measures as
Caution
soon as possible because it may not be possible to measure
correctly.
Error code and details
poor
Electrode sensitivity error
poor
poor
Asymmetric potential error
poor
Cause
The sensitivity
of the pH
sensor may be
degraded.
The calibration
solution (standard
solution) used for
the 1st point or
the 1st and 2nd
points is incorrect.
Calibration was
started before
the pH value
was stabilized
at the 1st point
or at the 1st and
2nd points.
Bubbles and
dirt adhere to
the electrode
surface.
Action
The electrode must
be repaired. Refer to
"Electrode replacement"
P.52.
Prepare a calibration
solution (standard
solution) with the correct
pH value.
Immerse the sensor in
a calibration solution
(standard solution) for a
while, and calibrate after
the pH value is stabilized.
Clean the electrode
surface and perform the
calibration again. If an
error occurs after cleaning
and calibration again, the
electrode must be replaced.
Refer to "Electrode
replacement" P.52.
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