Thermo Scientific 450iQ Instruction Manual page 187

Thermo Scientific
Problem
Instrument appears to zero,
but there is weak or no
response to span gas
Zero or Span will not
stabilize
Possible Cause
Settings>Advanced
Settings>Flash Lamp screen. If the
previously high signal drops to
zero or less when the flash lamp
is off, the problem may be caused
by scattered light from dust in the
optical bench. If so, carefully
clean the bench.
Span cylinder empty Check the source pressure.
Calibration system Check solenoids or other
failure hardware to be sure that span gas
is being delivered.
Flow rate of the diluted Check by-pass or atmospheric
span mix is adequate vent to verify that the zero air
system is providing more flow
than the instrument draws.
Instrument is not Check the sample flow and
drawing in span gas pressure 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.
SO or H S is being Replace any lines made of vinyl or
2 2
absorbed by tubing, plastics with fresh PTFE or
filters or dirt in the stainless steel. Replace PTFE filter
calibration system membranes that look dirty.
Remove any filters that are not
PTFE membranes.
Flash lamp has failed Listen for the rapid clicking of the
flash lamp. Check the flash lamp
voltage and intensity.
PMT has failed Check the PMT voltage and run
the optical span test. A good
optical span test indicates that
the PMT is OK and that the
problem is more likely the lamp.
Adjust PMT voltage if needed.
Flow rate of the diluted Check the by-pass or atmospheric
span mix is inadequate pressure vent to verify that the
zero air system is providing more
flow than the instrument is
Troubleshooting
Troubleshooting Guide
Action
6-3
450iQ Instruction Manual