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Thermo Fisher Scientific
Table 6–2. Troubleshooting - Calibration Failures
Malfunction
Cannot zero instrument or
there is a high background
signal when sampling zero
air. (Zero air should
produce a reading
equivalent to less than
10.0 ppm SO
.)
2
Instrument appears to
zero, but there is weak or
Possible Cause
Action
Zero air system is faulty,
Test against an ultra-zero cylinder
needs new SO
from a reputable scientific gas
2
scrubbers or requires
supplier or check effect of a new
maintenance.
chromatography grade activated
charcoal scrubber installed at the
instrument inlet.
Zero air flow rate is
Check by-pass or atmospheric
inadequate.
pressure vent to verify that the zero
air system is providing more flow
than the instrument is drawing.
Instrument is not
Check sample Flow and Pressure
drawing in span gas.
readings on the Diagnostics 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 in
the "Preventive Maintenance"
chapter.
Span gas containing
Verify that span gases connected to
SO
, NO, or a
the calibration system are shut off
2
hydrocarbon is
and leak-tight.
contaminating system.
Internal or external
Replace inlet filter (if installed) and
lines, filters, and other
as much of the tubing as possible.
sample handling
equipment are
contaminated or dirty.
Hydrocarbon kicker has
Replace the hydrocarbon kicker.
failed.
High scattered light
Go to Instrument Controls, select
Flash Lamp and toggle to OFF. 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 optical bench.
Input board failure
Disconnect the input board from the
interface board by unplugging ribbon
cable labelled "INPUT." The
instrument reading should drop to
zero or to a negative value.
Span cylinder empty
Check the source pressure.
Model 43i Trace Level-Enhanced Instruction Manual
Troubleshooting
Troubleshooting Guides
6-3
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Troubleshooting
