Mon Apr 25, 2011 4:18 am
The real challenge with cask ale is that it has to be drunk within a couple of days. If you try to keep it longer you have to do things that will cause the real traditionalists to shun you, talk about you behind your back and maybe even let the air out of your car tires.
The easiest solution is a "breather". This is like the regulator on scuba gear. It's connected to a CO2 tank and the other end goes into a barbed device that gets shoved in the hole where the spile normally goes. When beer is drawn the pressure in the pin or firkin goes down slightly and this moves the diaphram in the breather allowing some CO2 in to replace the beer rather than the air which would enter if all you had was a soft spile. Thus the beer stays blanketed with CO2 at one atmosphere, stays carbonated at that level and isn't subject to oxidation. A breather can, of course, also be connected to the gas port of a Cornelius or Sankey keg.
Another scheme that I have found effective (and you don't have to buy a breather) is to install valves (Micromatic sells them) on the gas and beer ports of the coupler. When the beer is not being consumed, the liquid valve is closed and the gas valve is open with the pressure set to just move the needle off the pin in the pressure gauge or a little more. The beer comes to equilibrium at slightly more than 1 atmosphere and is, thus, nicely carbonated. At service time gas valve is closed and the keg is bled down to the point where beer doesn't come out the swan neck when the liquid valve is opened. One can then draw pints from the engine, occasionally giving the keg a little blast of CO2 by opening the gas valve for a few seconds. It's a bit of a pain but I don't drink much ale and usually only do that when a particular friend is over who thinks hand pulled ale is the neatest thing since sliced bread. I can keep ales over a year this way and they are still pretty authentic.
One other problem with this scheme is the "night watchman" i.e. the beer that stays in the lines and cylinder of the engine. I have an arrangement with some John Guest valves and fittings that allow the engine to draw either from the keg or a bucket of water. This is used to flush remaining beer from the engine and lines at the completion of service for the day. If you forget to do it (and I have) pumping some water through days or even weeks later still gets the nasty stuff out.