70 Agilent 7890 Series Troubleshooting
3 Chromatographic Symptoms
FID Flame Goes Out During a Run and Attempts to Reignite
The following is an example chromatogram showing a flameout
from a large solvent peak.
After a flameout, the GC will try to ignite the flame three times.
The GC tries to reignite whenever the detector output falls
below the Lit offset setpoint, regardless of whether or not the
flame was extinguished. (In a very clean system, the baseline
output may be less than 2 pA.)
If the FID flame goes out during a run, do the following:
• See if an aromatic solvent peak or water extinguished the
flame.
• Check for a plugged jet.
• Verify that the gas flow settings are correct. Verify that Lit
offset is set appropriately.
If the FID flame attempts to reignite but is already lit, do the
following:
• Verify that the FID Lit offset setting is appropriate for the run
(typically
2.0 pA).
• Check to see if an aromatic peak or water extinguished the
flame.
• Check for a partially plugged jet. Measure actual hydrogen,
air, and makeup flows at the detector. (See “To Measure a
Detector Flow”.) Replace the jet as needed.
9
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4
3
2
1
23
4
5
min
pA
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