Problem
Probable cause
Possible solution
Unexpected or inaccurate
dissolved O
2
readings.
Air leak on product
sample line.
Set flow rate to 100 mL/min. Wait until stable, then
slowly double the flow rate.
The stable value of dissolved O
2
reading must be
the same as before. A variation related to flow rate
is a clear sign of an air leak in the line.
High residual current.
Place sensor in de-aerated sample and wait for
low reading.
Check concentration against low measurement
limit (refer to
Sensor membrane specifications
on page 4).
If concentration is significantly higher than low
limit, try replacing the membrane.
Calibration is out of specification
or response time is too slow.
Sensor incorrectly setup.
Check the sensor parameters on the instrument.
Re-calibrate the sensor.
Temperature
measurement incorrect.
Control the temperature with an external
reference.
Re-calibrate the sensor.
Barometric pressure
incorrect.
Calibrate the barometric pressure sensor using
the instrument.
Re-calibrate the sensor.
Cartridge incorrectly
assembled on sensor.
Verify the cartridge assembly is firmly screwed
onto the sensor and that the membrane is tight.
Re-calibrate the sensor.
Sensor electrodes are
dirty.
Clean the sensor using the ORBISPHERE
32301 cleaning and regeneration center as
explained in this section.
Re-calibrate the sensor.
Sensor maintenance is
required.
Replace the membrane by installing a new sensor
cartridge as explained in this section.
Re-calibrate the sensor.
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