Analytical Industries GPR-1200 ATEX Portable Trace PPM Oxygen Analyzer - Manual (Page 29)

29
8 Troubleshooting
Symptom Possible Cause Recommended Action
Slow recovery
At installation – extended exposure to air
At installation – sensor housing not properly
tightened
Air leak in sample system connection(s)
Abnormality in zero gas
Damaged in service - prolonged exposure to
air, electrolyte leak
Sensor nearing end of life
Continue purging sensor with preferably N2 zero gas
or sample gas with low ppm oxygen concentration
Check and tighten bolt in center of bottom section of
sensor housing, purge sensor as above
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 selection
Abnormality in 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 the gas (use a portable analyzer)
Response time slow Air leak, dead legs, distance of sample line,
low flow rate, volume of optional filters and
scrubbers
Leak test (above), reduce dead volume or increase
flow rate
O
2
reading doesn’t
agree to expected O
2
values
Pressure and temperature of the sample is
different than span gas
Abnormality in gas
Calibrate the analyzer (calibrate at pressure and
temperature of sample)
Qualify the gas (use a portable analyzer)