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Thermo Scientific
Problem
Reduced response or no
response to sample gas
with no alarm(s) indicated
Span calibration coefficient
outside acceptable limits of
0.5–2.0.
Excessive noise or spikes
on analog outputs
Possible Cause
Instrument is not properly
calibrated
Instrument is not drawing in
sample as expected
Detection circuit failure
PMT failure
Flash lamp failure
Bad span gas
System leak
Insufficient calibrator flow
Defective or low sensitivity
Troubleshooting
Troubleshooting Guide
Action
Perform a leak test as
described on page 5-5.
Verify the SO
background and
2
SO
coefficient are set
2
appropriately in the Calibration
screen.
Check sample flow and
pressure readings in the
Settings>Health Check>Status
and Alarms>Flow and Pressure
screen.
Use an independent flow meter
to check flows at the sample
inlet and exhaust bulkheads
(they should match).
Perform a leak test as
described on page 5-5.
Check the external plumbing for
leaks or other problems.
Check all external plumbing
and the source of the sample to
verify that the SO
is not being
2
absorbed by the sampling
system. Lines carrying SO
2
must be made from clean PTFE
or stainless steel.
Run the optical span text to
verify PMT and associated
electronics.
Check the PMT voltage. Adjust
if needed.
Check the lamp voltage.
Perform a detector Autocal. If
outside of spec, replace the
detector.
Verify quality of span gas.
Perform a leak test as
described on page 5-5.
Verify calibrator is providing a
flow of at least 0.8 LPM.
Check PMT voltage and run an
optical span test. Replace PMT
with known-good unit if
43iQ Instruction Manual
6-5
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