Feasibility of Nitrogen Standby

If they are never used why not turn all the GCs off.

We've thought of that, but we are planning to convert some of them as our back-up GCs for our existing ones. Are there any adverse effects on the GCs if we turn it off for a long time?

It should be fine provided you shut down and start up the GCs properly.  Please look at this slide deck for more details: Shutdown Procedures of GC and GCMS Products (agilent.com)

Hello,

If you have beetwin your gas source and GC any filter, then you need first to purge filters from previous gas, because if you just change method from carrier He to carrier N2, then due to the different velocities your GC will not be able to maintane constant pressure. If you don't have any filters beewtwin gas source and GC then question how you are going to switch beetwin two gases? For example in my setup I added several switch-off valves and three-way union to change carrier from He to N2, while make-up gas is still N2 in both cases.

Hello,

If you have beetwin your gas source and GC any filter, then you need first to purge filters from previous gas, because if you just change method from carrier He to carrier N2, then due to the different velocities your GC will not be able to maintane constant pressure. If you don't have any filters beewtwin gas source and GC then question how you are going to switch beetwin two gases? For example in my setup I added several switch-off valves and three-way union to change carrier from He to N2, while make-up gas is still N2 in both cases.

We will install a 3-way valve for N2 to He to just switch the gas supply on the GC, our make-up gas is also N2 so the gases involve has filters before entering EPC. Is this the same setup as you have buddy?

Hello,

3-way valve is a good idea, but unfortunately all I had was several 5180-4160 Tee, 1/8 in, brass, and several 0100-2144 Ball valve, 1/8 inch.

So I decided to make following setup.

In the setup below I am using He as carrier gas and N2 as make-up. When I need N2 as carrier I close 2 valve, 5 valve  and open 1 valve.

Tube 1 goes to headspace vial pressure gas and GC FID make-up gas. Tube 2 goes to gas filters to remove O2 and H20 and after to GC inlets.

Kind regards,
Rustam

Thanks, buddy! I really appreciate it.