Chromatography Forum

I just recently started using a GC, I had heard of but never used one until I got my new job. My gases are helium, hydrogen, and air. My question is when I am changing them do I need to have the GC off, or can it be running? The air tank is easy, but I have had problems when trying to change both the H2 and the He, if anyone has advice I would appreciate it!
PS nice to meet you all

If, by running you mean acquiring data, then no it should be "off"

If you just mean powered up but not acquiring data then ti should be OK.

However, check column flow after helium replacement.
Re-gnite the flame if replacing Hydrogen or air.

Alternatively, invest in manifolds (with two bottles attached) which can swithc automatically.

JGK response was good. To make a small addition to it, I would recommend that the oven temperature be lowered to 35°C or less as you could have a plug of air pass through your pneumatics when you change your carrier gas.

A small amount of damage could occur to your columns, especially if they are coated with a phase sensitive to oxygen.

The suggestion about having two bottles and a valve to switch from one to the other is a wise one.

best wishes,

Rod

thank you both so much, I have no problem in running the system it just bothers me a bit to change the tanks as I had never done it before. Manifolds definetly sound like a good idea to me, makes it much easier

Obtain safety information about changing tanks.

Obviously I know to check the saftey information I was just hoping that maybe someone here had other information that could be helpful like the manifold idea, thanks though for the most insightful tip of saftey manuals