I'm sometimes asked by bar owners about how to install and use a beer engine to serve cask ale, also known as 'real ale.' The implication is that this simple hand-pump device will somehow 'improve' the cask ale that's being served, increasing the level of carbonation and extending the lifespan of the beer. That is, of course, patent nonsense. A handpump does neither; it's simply a hand-pump.
To that point, here's a guest post by Steve Hamburg, one of the foremost cask cellarmen in the United States. It is taken from Cask-USA, an online forum devoted to cask-conditioned ale in the US, hosted at Yahoo! Groups, reprinted with permission.
In theory there should be NO difference between a beer served by gravity or handpump, unless you expect all your handpumped beers to be served through a tight sparkler. There's simply no way that gravity pour can replicate the thick, cascading head, but that doesn't mean the beer should be flat and lifeless.
The issue, as it almost always is with cask ale, is poor cellaring technique. Too many bars/pubs will over-vent their cask beers (breach the cask and leave the porous soft spile in too long) and then use the handpump and a tight sparkler fitting to artificially compensate for what is essentially a pretty flat beer in the cask.
The goal of the cellarman is to optimize the level of natural carbonation that's consistent with the beer style and to serve each beer in a manner that best expresses the aromas, flavors, and mouthfeel. Over-venting is poor practice - there's simply no way you can get conditioning back into flat beer. Then again, if the brewery doesn't understand cask conditioning and racks flat or under-primed beer into the cask, even proper cellar technique won't help.
When I cellar beers my goal is always the same: to maximize the natural sparkle and clarity, no matter how it's served. Again, you should NEVER need a tight sparkler to produce carbonation in a cask beer. I, for one, don't like sparklers at all. But I recognize that many people prefer the creaminess produced by them, and also that this may be a desirable characteristic in certain styles (e.g., mild, porter, stout).
In practice, especially at festivals, it can be extremely difficult to maximize natural conditioning. That's because many beers, especially strong ales and barleywines, may require lengthier aging to build up suitable levels of carbonation. But pulling through a handpump will only give you the illusion of carbonation - the beer will be just as flat regardless of serving method, but the handpump just froths it up a bit.
Based on your experience, I can understand why you guys generally prefer handpumped beers. Just understand that there's nothing really magical about pumps. The same beer - if cellared properly - should have the same sparkle regardless of how it's served.
And then there's the problem of over-primed casks, common in the U.S. That's a topic for another day.
This post is one in a series on Cask Ale: Fobbing at the Tut.