Hach-Lange HQD - Gel filled ORP_Redox electrode MTC - Manual (Page 14)

14 DOC272.53.80033
Drifting/Inaccurate
readings
Contaminated platinum disc Clean the electrode.
Clogged reference
Rinse reference junction holes with deionized water
thoroughly and gently tap the electrode with hand or
shake the electrode down to remove any air bubbles.
Improper storage conditions
Clean or condition the electrode and attempt
recalibration.The electrode may not function correctly if
the electrode has been left dry for extended periods of
time. Attempt to recondition the reference junctions by
soaking the electrode tip in a 3.0 M KCl storage solution
for 1-2 hours. Rinse with deionized water prior to use.
Electromagnetic Forces (EMF) such as
voltaic cells, thermoelectric devices,
electrical generators, resistors and
transformers.
Avoid testing in areas where EMF is present. For testing
in process units (i.e. spot checking), make sure the
equipment is grounded.
Air bubbles around inner reference
electrode Gently tap the electrode with hand or shake the electrode
downward to remove any air bubbles
Out of limits
Check standard value is outside of limits
set in the current method
Verify that the standard is within the limits of the current
method.
Create a new method that expands the acceptable limits.
Measurement value is outside of the
measurement limits set in the current
method.
Verify that the sample is within the limits of the current
method.
Create a new method with an expanded range.
Calibration adjustment offset value
outside the limits set in the current
method.
Verify that the standard is within the limits of the current
method.
Create another method that expands the acceptable
limits.
Storage cap not removed Remove storage cap
Temperature out of
range
Calibration temperature value is outside
of range
Verify that the sample temperature is within the range of
the electrode.
Verify that the temperature sensor is working correctly.
Measured temperature is outside range
of the electrode
Verify that the standard temperature is within the range of
the electrode.
Verify that the temperature sensor is working correctly.
Check standard temperature value is
outside of range Verify that the Check Standard temperature is within the
range of the electrode.
Troubleshooting (continued)
Message or
symptom Possible cause Action