6890 FID erratic makeup gas flow

Question

One of our 6890 GC's shows a continually varying (in one minute the reading can vary up or down 20 ml/min) flow for the makeup gas. I shut down all the heated zones and turned the nitrogen flow off at the cylinder and the display on the GC still showed a flow present which of course was drifting up and down. All the other gas flows look normal. Any ideas on what could be wrong.

james_jenkins · Accepted Answer

This could be an EPC problem. As long as the gas supply is adequate with proper pressure, there is not much more to the makeup gas flow. 
 Regards 
 James

ISH · Answer

Hi, 
 You can do one thing before replacing EPC.Remove Air, Hydrogen and Makeup lines from the back of GC and then see that flow is zeroing or not, in GC display. 
 If flow is zeroing in GC display then after you can connect all lines to EPC again and use it. 
 Second thing if flow is not zeroing then remove EPC from system and install back again. 
 If still problem persist then you have to replace EPC.

6890 FID erratic makeup gas flow

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