Fpd Output Too High Or Too Low - Agilent Technologies 7890 Series Troubleshooting Manual

3
Chromatographic Symptoms

FPD Output Too High or Too Low

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• Verify that the correct filter is being used. Do not use a
phosphorus filter with sulfur-optimized flows or a sulfur
filter with phosphorus-optimized flows.
• Check the position of the column as installed in the detector.
• Check the gas purity.
• Verify that the flows are optimized for the filter being used.
Monitor the FPD output. The table below provides examples
of detector output when the filter installed in the detector
and the gas flows in use do not match.
Outputs
Gas flows optimized With sulfur filter
for
Sulfur 30 to 50
Phosphorus 240 to 250 (high)
Besides having a mismatch between the filter installed and a
particular set of gas flows, check the FPD signal output with the
flame lit:
• If the output is 0.5 to 3.0, check that the flame is ON.
• If the output is 0, check if the electrometer is turned OFF or
the signal cable is disconnected.
• If the output < 30, the flame may be in the wrong position.
Check detector flows, column flow, and column position. See
the following:
• To Measure a Column Flow
• To Measure a Detector Flow
With phosphorus filter
10 to 12 (low)
30 to 50
Agilent 7890 Series Troubleshooting