h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

Hello,

Been pondering this one all day....how on Earth do Beer Taps work? Presumably it's not gravity since the barrels would need to be higher than the taps (and they're not, they're underground). How do they make the beer flow so effortlessly into my glass when real ale must be pumped energetically by a young lady with an overdeveloped forearm? Do they force a gas into the back of the barrel, creating enough pressure to make it flow upwards or is there some very clever way of making this happen? I'm dying to know, it's bugging me!

Regards,
Dave

Compressed gas is used to make it flow through the taps, give you wind and make you feel like hell!!!!

But that only works with keg beers. For real ale (ie handpumps) the pump system is some sort of syphon I think. The pump draws up a piston which creates a space at the top of the beer pipe. Nature abhoring a vacuum pushes the beer (or whatever) along the pipe because of the air pressure in the barrel being higher than that at the other end. Then there must be some sort of valve and pipework that it all then comes out of and into the glass.
This could of course be total and utter rubbish of course.

Phil - you're exactly right. It works on exactlythe same principle as the old water pumps - piston moves up creating a vacuum and opening a one-way valve to the liquid source which draws water in. Piston goes down forcing liquid out through the exit one-way valve.

Newer systems rely on caniosters of pressurised CO2 which also gives the smaller tighter bubbles as this tends to dissolve under sufficient pressure. uses nitrogen which is why it's head is "cremier".

It was Guinness that really pushed the nitrogen gas mix. Loads of others do it now (mostly creamflow or smooth types of ale). I'm guessing that carling (bass) has experimented trying it with lager - carling permier I think.