180 Agilent 7890 Series Troubleshooting
8 Troubleshooting Tasks
To Measure a Detector Flow
Detectors, especially detectors with flame, require precise flow
measurements to function properly. Incorrect flows are caused
by:
• Restrictions in the supply line, which will cause a Not Ready
message on the GC display (all detectors)
• A leaking column or column adapter fitting (all detectors)
• A plugged jet (FID, NPD).
• A leak in the burner chamber, window seal, or ignitor seal
(FPD)
• A pressure sensor that needs to be zeroed. (See To Zero the
EPC Module Pressure Sensor.)
• An EPC valve that is not operating correctly.
To isolate the problem, compare the flow of one channel of gas
against the actual flow rate.
Measuring FID, TCD, uECD, and FPD flows
1 Gather the following:
• Appropriate flowmeter adapter tube (can be found in the
GC ship kit)
• Electronic flowmeter calibrated for the gas and flow rates
of concern
2 Set the oven temperature to ambient (35 °C).
3 Turn off the column flow and pressure.
4 Shut off all detector gases.
Hydrogen (H2) is flammable and is an explosion hazard when
mixed with air in an enclosed space (for example, a flow meter).
Purge flowmeters with inert gas as needed. Always measure
gases individually. Always turn off detectors to prevent
flame/bead autoignition.
To avoid damaging the column, cool the oven before turning off the
column flow.
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