Troubleshooting
6850
6850
Released: April 2004 6850 Series Gas Chromatograph Service Procedures 302
The noise could also be attributed to air flowing
over the interconnect interface. In this case,
install an FID interconnect cover (part number
G1531-00220) to minimize noise (see “Flame
ionization detector” on page 1-142).
If the problem persists after gas purity issues are
addressed, there could still be a problem with the
FID electrometer or FID electronics board.
Replace and reevaluate.
Flameout (flame will not light)
The purpose of this section is to outline a logical
procedure for troubleshooting FID ignition prob-
lems, including lighting the FID, flameouts during
injection, and intermittent re-ignition during a
run.
The 6850 FID uses a hydrogen flame to burn
organic samples, resulting in increased ionization
that is measured as a current (values up to the
10^6 pA range).
The FID will attempt to re-ignite if the detector
background in picoamps drops below the Lit
Offset value that is set in the Configure Detector
menu. The Lit Offset is defined as the difference
between the FID output in picoamps with the
flame lit and the output with the flame off (typi-
cally the output of the FID with the flame off will
be a very low value close to or equal to 0 pA.)
The default Lit Offset value is 2.0 pA.
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