[phth]

What is the best flow rate for an inert gas within a schlenk line: slow, fast, or a variation between? Hypothetically if one were conducting an extremely sensitive reaction to water/oxygen getting into the schlenk line. My thought was that a slower flow rate may be better.

[wildfyr]

I'm not sure why you think slower would be better? Faster rate means any water or oxygen that gets in will be diluted with nitrogen that much faster.

[zarhym]

In small scale (less then 2L), we use nitrogen balloon. In large scale (over 10L), we use nitrogen cylinder. It works fine as long as there are continuous bubbles in the bubbler.

This works for up to 15L 2.5M t-butyl lithium reaction.
We don't use schlenk line, since it's less convenient compare to balloons.