Section 9 Troubleshooting
Keep the probe clean and in the recommended storage solution when not in use for the best
accuracy, stabilization time and life of the probe.
Problem
Possible cause
Solution
Decreased probe performance
causes slow stabilization and
prevents accurate calibrations or
measurements.
The glass sensor is dirty.
Clean and condition the probe.
Refer to
on page 11.
The reference junction is
clogged.
Clean and condition the probe.
Refer to
on page 11.
The filling solution has
contamination.
Replace the filling solution.
Refer to
on page 12.
The probe is not conditioned
to the sample sufficiently.
Condition the probe. Refer to
on page 5.
The glass sensor has become
dry.
Soak the probe tip in buffer
solutions. Refer to
on page 12.
The calibration slope of the
probe has changed.
Increase the accepted slope
limit settings if possible, or
contact technical support.
Sample properties cause slow
stabilization or inaccurate
measurements.
The sample absorbs carbon
dioxide (CO
2
) from the air,
which causes the pH value to
slowly decrease in low ionic
strength (LIS) or high purity
samples.
Use the LIS chamber for
LIS/high purity samples to
prevent CO
2
absorption.
The sample temperature is
low, or there is a large
temperature difference
between samples.
Increase the sample
temperature or adjust the
temperature of different
samples to be the same (within
2 °C (3.6 °F)).
Procedure problem causes slow
stabilization and prevents
accurate calibrations or
measurements.
The filling hole is closed.
Open the filling hole during
use.
Air bubbles are around or
below the probe tip.
Carefully tap or shake the
probe to remove air bubbles.
The electrical connection
through the reference junction
is not sufficient.
Shake the probe in the solution
from side to side to refresh the
reference junction.
The stir speed is too slow or
too fast.
Try a different stir speed.
An incorrect buffer solution
was used or the buffer
solution has contamination.
Use the specified buffer
solutions of good quality.
The protective tape was not
removed from the filling hole.
Remove the tape from the
filling hole. Refer to
on page 5.
14
English
Summary of Contents for PHC301
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