Advanced Instruments Inc.
8. Troubleshooting
Symptoms
Possible Cause
Recommended Actions
Slow recovery
At installation, defective sensor
Air leak in sample system connection(s)
Abnormality in zero gas
Damaged in service - prolonged
exposure to air, electrolyte leakage
Sensor nearing end of life
Replace sensor if recovery
unacceptable or O
2
reading fails to
reach 10% of lowest range
Leak test the entire sample system:
Vary the flow rate, if the O
2
reading
changes inversely with the change
in flow rate indicates an air leak -
correct source of leak
Qualify zero gas (using portable
analyzer)
Replace sensor
Replace sensor
High O
2
reading after
installing or replacing
sensor
Analyzer calibrated before sensor
stabilized caused by:
1) Prolonged exposure to ambient air,
worse if sensor was left in air un-
shorted
2) Air leak in sample system
connection(s)
3) Abnormality in zero gas
Allow O
2
reading to stabilize before making
any calibration adjustment
Continue purge with zero gas
Leak test the entire sample system (above)
Qualify zero gas (using portable analyzer)
High O
2
reading
Sampling
Flow rate exceeds limits
Pressurized sensor
Improper sensor selection
Abnormality in sample gas
Correct pressure and flow rate
Remove restriction on vent line or open
SHUT OFF valve completely
Replace GPR/PSR sensor with XLT sensor
when CO
2
or acid gases are present
Qualify sample gas independently
Response time slow
Air leak, dead legs, longer distance of
sample line, low flow rate, high volume
of optional filters and scrubbers
Leak test sample system bringing sample
gas to analyzer, reduce dead volume and/or
increase sample flow rate
O
2
reading doesn’t
agree with expected O
2
values
Pressure and temperature of the
sample may be different than the span
gas used for calibration
Abnormality in the sample gas
Calibrate the analyzer (calibrate close to the
pressure and temperature of the sample
gas)
Qualify sample gas independently
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