Analytical Industries GPR-35 Oxygen Analyzer - Manual (Page 28)

Advanced Instruments Inc.
28
8 Troubleshooting
Symptom Possible Cause Recommended Action
Slow recovery or
response time
At installation, defective sensor
Failure to purge gas lines with Bypass, air leak in
connections, dead legs, distance of sample line, low
flow rate, volume of optional filters and scrubbers
Abnormality in zero gas
Damaged in service - prolonged exposure to air,
electrolyte leak
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 unshorted
2) Air leak in sample system connection(s)
3) Abnormality in zero gas
Allow O
2
reading to stabilize before making the
span/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 - CO
2
affects GPR sensor
Abnormality in gas
Correct pressure and flow rate
Remove restriction on vent line, replace sensor
Use XLT sensor when CO
2
or acid gases are present
Qualify the gas (use a portable analyzer)
Reading doesn’t agree
to expected O
2
values
Pressure and temperature of the sample is different
than span gas
Abnormality in gas
Failure to allow reading to stabilize before zero
and/or span calibration adjustments
Calibration error caused by turning the zero and/or
span potentiometer more than ½ turn at a time
(electronics need time to keep up
Calibrate the analyzer (calibrate at pressure and
temperature of sample)
Qualify the gas (air calibrate and/or use portable analyzer)
Repeat calibration procedure and allow reading (sensor) to
stabilize
Repeat calibration, allow reading to stabilize and make
adjustments ½ turn at a time