Hach-Lange PHC735 User Manual
Page 13
Message or symptom
Possible cause
Action
Slow stabilization time
Tape not removed from the
filling-hole
Remove the tape.
Contamination in the glass
sensor
Clean the probe. Refer to
on page 10.
Contamination in the filling
solution
Drain and replace the filling solution with fresh solution.
Filling hole closed
Make sure that the filling hole is open and above the
solution level.
Poor contact between reference
junction and solution
Shake the probe in the solution from side to side to
refresh the reference junction.
LIS sample
Soak the probe in the sample for 10 to 15 minutes before
the initial measurement or use a LIS chamber or flow-
through cell.
Low sample temperature or
temperature difference between
samples
Examine the sample temperature. The lower the
temperature or the higher difference of temperatures
between samples, the longer the stabilization time will
be.
Air bubbles around inner
reference electrode
Carefully tap the probe with hand or shake the probe
downward to remove any air bubbles.
Dehydrated glass bulb
Rehydrate the probe. Refer to
on page 11.
Not sufficient electrolyte flow
1
Open the sleeve junction.
pH probe too old (membrane
degradation)
Replace the probe.
Calibration errors
Calibration not done correctly
Calibrate again with fresh pH buffers.
Contaminated glass sensor
Clean the probe. Refer to
on page 10.
Slope exceeds the criteria for %
of theoretical (as defined in the
method slope limit)
1.
Adjust the slope limits by changing the PHC735
calibration settings and method.
2.
Calibrate again the probe.
3.
Make a check standard to examine the performance
of the probe.
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