I been searching and searching and can't seem to find an answer. My best guess is that the outlet, where the beer comes out, is attached to a tube or pipe that runs down to almost the bottom of the keg. Then the inlet, where the co2 comes in, just goes straight in the top, where there is no fluid. Therefore, when the co2 pushes against the top of the liquid, its forced out through tube/pipe. My question is: if this is how a keg works, won't there always be a little bit of beer left at the bottom? If this is the case, how would I get to that last little bit? Obviously with a hombrew keg you could just open her up and enjoy, but I'm dealing with commercial brew right now.