Hach-Lange PHC28103 User Manual
Page 12
Message or symptom
Possible cause
Action
Slow stabilization time
Tape not removed from the filling-
hole
Remove the tape that is over the filling hole.
Contaminated glass sensor
on page 10).
Contaminated filling solution
Drain and replace the filling solution with fresh solution.
Filling hole closed
Open the filling hole while in use by removing the filling-
hole cap from the filling hole.
Poor contact between reference
junction and solution
Shake the probe in the solution from side to side to
refresh the reference junction.
Probe not prepared for LIS sample For the best stabilization time, soak the probe in the
sample for 1 to 3 minutes before the initial measurement.
Low sample temperature or
temperature difference between
samples
Check the sample temperature. The lower the
temperature or the greater the difference of temperatures
between samples, the longer the stabilization time will
be.
Air bubbles around inner
reference electrode
Gently tap the probe with hand or shake the probe
downward to remove any air bubbles.
Calibration errors
Calibration not done correctly
Recalibrate using freshly prepared pH buffers.
Contaminated glass sensor
on page 10).
Slope exceeds the criteria for % of
theoretical (as defined in the
method slope limit)
1.
Widen the slope limits by changing the PHC281
calibration settings and method.
2.
Recalibrate the probe.
3.
Run a check standard to check the performance of
the probe.
Drifting/Inaccurate readings
Contaminated glass bulb
on page 10).
CO
2
absorption (for low ionic
strength or high purity sample)
Use the LIS chamber for LIS/high purity samples to
prevent sample contamination.
Clogged reference
Rinse the reference junction holes with deionized water
and then gently tap the probe with hand or shake the
probe to remove any air bubbles.
Improper storage conditions/
Dehydrated glass bulb
Clean or condition the probe and do recalibration.The
probe may not operate correctly if the probe has been
left dry for a long time. Condition the glass sensor and
reference junctions again:
1.
Soak the probe tip in the 4.01, 7.00 and
10.01 buffers each for 5 minutes.
2.
Rinse with deionized water. Blot dry with a lint-free
cloth.
3.
Calibrate the probe.
Electromagnetic Forces (EMF)
such as voltaic cells,
thermoelectric devices, electrical
generators, resistors and
transformers
Do not test in areas where EMF is present. For testing in
process units (spot checking), make sure that the
equipment is grounded.
Colloidal and/or particulates in the
filling solution.
Replace the filling solution, calibrate and test again.
Air bubbles around inner
reference electrode
Gently tap the probe with hand or shake the probe
downward to remove any air bubbles.
Out of range
Measurement value is outside of
range
Make sure that the sample is within the range of the
probe.
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