Chromatography Forum

Hi everyone

I have questions about EFC of Varian CP-3800 GC.
How is total gas flow calculated? When I set column flow to 1 ml/ml and split ratio to 10, a total gas flow is 22 ml/min. In other column flow and split ratio values I also have excess flow in total flow rate.

When septum purge is altered, total flow rate is remained constant. Does septum purge flow contributed in total gas flow?
I test these values in two Varian CP-3800 instruments.

Another question is about gas saver mode function:
I set total gas flow of 2 ml/min in gas saver mode (which is activated after 5 min when active method is not run). Is it possible knowing how much column flow rate is when I set column flow of 1 ml/min and split ratio of 100 in active method (septum purge flow =0). How gas flow rates are set in gas saver mode?

Thanks.

Check that you have the column dimensions entered properly. Also measure the actual flow out of the split vent and septum purge using an independent flow meter.

A gas saver flow of 2 ml min will not be enough to maintain inlet pressure, you will get an error that will cause the GC to shutdown.

Peter