How do you know when you've purged all the air out of a corny keg and there is only CO2 left?
The way my kegging setup is I have to chill and serve from 2 1/2 gallon kegs. I have 2 of these small kegs.
Right now I've got one empty 2 1/2 gallon keg, a full 5 gallon keg, and a near-empty 2...