I was struck recently how often bartenders will very often pour out half a glass of beer because it’s too foamy then start again. I appreciate the desire to give me a glass of beer instead of foam, but this has to amount to huge quantities of wasted beer over time. Why isn’t there some simple pressure control technology to control the beer/foam ratio for perfect pours every time?
There is a very simple technical solution to this problem. When the fluid reaches the rim of the glass it’s time to stop pouring.
Yes there is. Train the servers better. It is possible to get a better pour and not waste so much beer, but many servers are sloppy and trying to get the beer poured as quickly as possible. I’ve been to plenty of pubs where they watch the tap like a hawk and stop the beer right at the brim, with little spillage.
It could also be that the line balancing isn’t set up correctly. Too much PSI, or beer lines are too short, or the cooler is too warm. All of those factors have to be in sync in order to get a non-foamy pour. If a keg has been sitting at room temp and then hooked up to the system that’ll cause a lot of foam until it cools down to the fridge temp. Commercial runs have 1/4" beer lines which need to be loooong. Absolute minimum is 10’, but 20’ to 40’ of beer line is better per tap. Shorter lines with high PSI means more foam.
Keep in mind my experience is only with building a kegerator or two at home, I’m not a professional by any means. I did a lot of research before building them though.
Proper control of foam requires several elements, of which pressure is only one. The beer must be properly carbonated in the first place; the beer lines must be clean and smooth inside; the storage temperature for the keg must be correct and stable; the dispensing pressure must be right; and the glasses must be perfectly clean. Perhaps the most common culprit is temperature: warm beer, warm lines – warm anything will drive CO[sub]2[/sub] out of solution, and bars with overly long unrefrigerated lines can always have foaming problems.
Similarly, if kegs are not stored properly, there will be foam. For instance, if the keg is in the same refrigerator as the bottles and cans, constant opening and closing will drive up the temperature. Other mishandling can affect the beer: tapping too soon after delivery draws on a keg full of foam; emptying the keg too far will fill the lines with foam (even maintaining proper pressure on a somewhat low keg will involve a ever-increasing volume of CO[sub]2[/sub]).
Old, kinked, or dirty lines will foam the beer despite all precautions. Finally, it’s true that pressure control is essential, and many regulators are way out of calibration, but this is pretty easy to adjust (unfortunately, some impatient operators set the pressure too high, to achieve a faster draw – this is understandable, but self-defeating).
ETA: Shakes fist at EvilTOJ – all that formatting time!
The glasses must also be clean. Not just clean, but “beer clean” which is an actual industry term for absolutely, meticulously, spotlessly clean.
Same goes for all of the lines, taps, and so on. Keeping a draft beer system clean and running properly requires a large investment of effort.
More troubleshooting info is here.
There a device called Turbo Tap which seems to do some of what the OP wants, and it pours a faster pint. I’ve never actually seen them used at a bar, though, and I don’t know what its effects would be on foamy lines.