Sanke Question

I'm a little confused about how a Sanke works. I recently took one apart and was surprised to find that it just has a single 1" diameter dip tube going from the valve to the bottom. It seems to me like if the CO2 tank is pushing into the same tube that the beer is supposed to be drawn out with, then the gas would just flow out of the tap without pushing any liquid. Can someone explain to me how this works?
Thanks

Not entirely sure but my guess is they either use the valve to fill with beer then carbonate it after that or they just fill pre-carbonated beer in one shot. You could technically run gas into a liquid-in on a corny too.

I've wondered the same thing. It looks like once the tap lever is pushed, it puts gas and beer in the same space.

Yeah, the reason I was wondering is I've heard of people kegging homebrew in sankes without using priming sugar. The only thing I can think of is maybe as CO2 enters, it bubbles up from the bottom of the tube and gets added to the headspace, but it seems like when you open the tap, you should be releasing a pretty big volume of gas (the full volume of the 1" diameter diptube) before the beer starts flowing. Seems like this would kill your pressure.
Anyone have experience with this?

Ok, I think I figured this out.
The rubber seal doesn't actually remain seated inside outer ring, the tapper pushes the seal down and pumps the gas around the outside of the seal directly into the headspace.
I found this pic:


Now I can sleep.