GC ignition fault during sample analysis.

Question

Hi,

Have this issue with an Agilent 6850 GC:

The system performs normally during the pre-run: the oven temperature, front inlet total flow/inlet pressure and signal 1 valve values are all normal/stable. When we switch to the test method and start sample analysis, we have the following errors:

Detector H2 Flow

Detector Air Flow

It tries to ignite several times, dropping in and out of ready status before failing with fault 214. When we switch back to the pre-run, it ignites and behaves normally. We've checked for leaks although these seem unlikely given that it performs normally on the pre-run.

Does anyone have any ideas what might be causing this problem?

Thanks.

matt99 · Accepted Answer

Have been running the system all day and the adjustment to the lit offset value has resolved the fault. I don't have a definitive cause for why the system should be happy with 2.0 for the past 11 years but not now. We use a hydrogen generator and a zero grade air generator to supply the GC: each are serviced at 6 month intervals with the last service 2 weeks ago. The only factor I can think of is that the generators are running well and the gas/air is unusually pure: I understand that an offset value of less that the default 2.0 might be required if you're using high purity gases. However, if the value is too low, the detector may never try to re-ignite. Thanks for the feedback.

GC ignition fault during sample analysis.

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