Chromatography Forum

Hi All,
I'm having an issue with my carrier gas which is causing the instrument to go into error mode.

PTV: 200C, splitless 1uL
Column: Carbowax 25m x 0.25mm x 0.20um
FID: 300C
Carrier: Helium at 2mL/min
Start the oven programme at 50C and carrier flow is stable. As soon as the oven gets to 100C, carrier gas flow drops to 1.2mL, oven reaches 200C and flow drops to 1mL with error and standby mode activated.

Can anyone offer any ideas? Liner, septum changed, column refitted.

Thanks in advance!

What does the error message tells you? Is the method constant flow? Which instrument type is this? Did you check for leaks with a leak detector?

Error message is: EFC Time out. Method is constant flow. Have checked for leaks and there doesn't appear to be any. However, I am not convinced as the drop in flow only occurs with temperatures >100C. Instrument is a SCION 456 GC

What could be causing this is that your helium tank is not giving enough pressure to the instrument. As the oven temperature increases, more pressure is needed to maintain the same flow.

Note that i'm not familiar with your instrument. If you want to be sure, check the recommended pressure for helium in your instrument manual.

I second the last post. Check your instrument delivery pressure. When running, to maintain 2.0 mL/min at 100C you should be around 21psi. At 200C you should be around 28psi. While the instrument is idle, try setting the inlet pressure to 40psi and see if it holds. If not, increase delivery pressure until it does.

Thanks guys, turns out someone had been messing with the septum purge dial so a re-calibration was all that was needed.

Best Regards.