I already have this "gas seperator" hooked up to my DIY which I use BTW as a bubble counter instead. simply, it doesn't! It shouldn't be called a gas seperator but rather a liquid/gas seperator. All this is made for is to let the yeast water (liquid) collect at the bottom.
Ok, I have to deal with this now, b/c its really starting to bug me. The most common misconception for why this simple 20oz bottle acts as a "gas seperator" is that different gasses sink and settle in layers. People think that since alcohol vapor is heavier than CO2, its will sink and let only CO2 escape. This is not true!
Erase it from our memory and never think of it again! If this was true all the CO2 in the atmosphere would be at ground level and all of us would be suffocating.
Gasses have an relatively extremely high kenitic energy (motion) compared to solids and liquids; In a vacuum a gas molecule travels at thousands mph and in the regular atmosphere they are colliding like crazy with each other and constantly mixing. The fact that gasses have such relatively enourmous kinetic energy makes gravity (meaning also their weight since weight is a function fo gravity) irrelevant.
I think most people get hooked on this misconception because they have seen dry ice, which is frozen cold CO2, sublime into a gas and sink/creep along the floor. This is only becuase it is cold=alot more denser. And anyway, it quickly disappears in seconds because it reaches the room temp and mixs/spreads with the air. Gasses only settle b/c of different temperatures, besides that gasses never settle @ then same temp.
Sorry if I made the wrong assumption of how you were thinking Malkore, but I noticed alot of people think this way anyway so just had to deal with it.