A great glass of draft beer poured from a keg can seem tricky on the first few pours. You may pour a beer and get a glass full of foam, and other times you may pour and get no foam at all. It takes more than just a glass tilted at a 45 degree angle, but if you pay close attention to all the key dispensing elements (temperature, pressure, tube length, keg and glass) you should not have any issues.
Pouring consistent glasses requires a practical understanding of how carbonated beverages work in a dispensing system. Beer is not like water — it pushes back where non-carbonated liquids will simply flow with gravity or the push of air and other gases. To understand how this push operates you should understand beer’s carbonation level and the carbonation’s relationship to temperature. You can then begin to understand how to calculate CO2 push, preferred beer line length and the proper serving temperature for each style of beer you plan to dispense from your kegerator.
In order to fill a glass with a well-balanced beer, the keg’s dispensing gas must be balanced and fully saturated into solution for that specific beer’s style. Moving kegs around after carbonation has been completed will cause agitation and release some of the infused gas. The result is extreme foam when immediately tapped and served.
The key to solving this problem is to allow the beer to settle and return to optimal serving temperatures in your kegerator. It is best to let a keg sit 24 hours after vehicle transport, but often this is not practical. Try to hold off, however, for at least an hour if you are just moving it from, say, the garage to the keg fridge.
The length of the beer line and the length of the gas line can also affect the amount of push needed for optimal pouring. Most home draft systems will have beer line of 3⁄16-inch inner diameter (ID), but it is good to check and make the adjustments necessary. Look at the type of beer line and CO2 gas line that comprise your home draft system. If possible, note the restriction value of the line. Some beer and gas lines may have the same inner diameter, but because of the materials they are made from, they will expand or contract at different rates. This quality of your line is called the restriction value.
There will be some restriction from gravity and from draft hardware such as any shank and the spigot, but it is pretty negligible. Gravity has an effect, and it is only 0.5 pounds per foot of rise or fall of additional restriction.
Rule of Thumb: For determining the beer line length you can take the ideal pressure, add five and then divide by the beer line’s restriction value per foot. If the beer isn’t flowing fast enough for you, you can try cutting down the beer line length a little at a time until it feels right.
There are some other considerations as well, such as making sure that your beer line is cold and the possible use of beer gas (CO2 and Nitrogen mix). There are some people with more complicated formulas than this to accommodate for various factors, but I have found this one to work quite well.
If you have more than one type of beer that is being served from the same gas source, you will want to either split your CO2 line or add a secondary regulator to step down the pressure to the keg of beer that will be served at the lesser pressure. The most expedient solution is to daisy chain secondary regulators to your primary CO2 regulator. This will allow you to adjust the pressure according to the rule of thumb I just mentioned, so that if you have two beers that are being served from the same cooling chamber, you can adjust the pressure on the different kegs to match the ideal pressure for the non-ideal temperature.
Cleaning Beer Lines
Cleaning the beer lines of your home draft system with a beer cleaner is vital to maintaining good flowing beer. The beer line cleaning chore should be undertaken on a regular basis. It is a good idea to clean the beer lines in between each keg change. If this seems like too much for you, then at least once every month is recommended. You will notice the results of regular beer line cleaning: keeping your beer lines fresh improves taste and prevents particles from causing over-foaming from the tap.
Just like all your brewing equipment, cleaning your beer lines requires two steps: cleaning and then sanitizing. Beer Line Cleaner (BLC) or Powdered Brewery Wash (PBW) are both good choices for the cleaning step, and Iodophor is a good sanitizer. Iodophor is used to create a water-based solution (the ratio comes on the Iodophor bottle) in a bucket of water. There are also many different types of cleaners these days that have emerged specifically for the purpose of cleaning beer lines. These products are specially developed to remove the sediment that builds up in the lines as a result of yeast particles that cling to the insides of the beer lines. The theory is that any little rough spot in the beer lines, the spigot, or even the glass, gives the CO2 infused into the beer a chance to escape, creating excess foam. Ideally, you want a cleaner that will take away the yeast and malt sediment without “roughing” up the plastic tube or any other part of the draft system on the inside. This is why nonabrasive products are used exclusively for the purpose of cleaning beer lines. BLC has been a very popular all-purpose cleaner for a while now, but Power Punch 22 is a newer product from Perma that has been specifically tailored to more efficiently remove yeast residue from your beer lines with less caustic effects. Both products are biodegradable, and both are made especially for beer line use. No matter which beer line cleaner you use for cleaning and maintaining beer lines, however, the actual process for cleaning and sanitizing the lines will be the same. The choice of chemicals is up to you — find a cleaner and sanitizer that you can afford and live with.
Once you have your cleaning and sanitizing solutions ready to go, it’s time to get started. The process goes like this: take your nozzle and hoses apart and soak and clean them with your cleaning solution followed by a thorough rinse. Next, let the parts soak, submerged, in a bucket with Iodophor solution for ten minutes or so. Unwanted bacteria will be destroyed — and, if your Iodophor and water solution is in the correct ratio, you will not have to rinse. An additional technique is as follows: make an extra a gallon or two (3.8–7.5 L) of Iodophor solution and run it through your beer lines for a few minutes. Next, take your taps apart as you did with your lines and thoroughly clean them followed by a 10-minute soak in your sanitizing solution. Keep in mind that the outsides of your beer lines should be sanitized as well.
If the temperature and/or CO2 push of the beer in your draft system is only a little bit off it can greatly effect the carbonation level of the beer, and also the beer’s taste. The first thing to understand is that each beer type has a certain temperature that it should be served at and a certain pressure that the beer should be dispensed with while at that temperature. If the temperature changes even two degrees Fahrenheit (1 °C) it can cause the beer to taste either flat or cause over foaming.
This is because beer is a solution of gas and liquid. The saturation point of beer changes dramatically with temperature. If you are a homebrewer then you know that it is easier to add malt syrup to hot boiling wort than to mix it into a solution with cool or even warm water. With CO2 it is different — the opposite relationship to temperature is true. The lower the temperature of the beer the easier it is to infuse the beer with CO2 gas. As the temperature of the beer goes up the saturation level goes down. This causes the CO2 gas to be forced out of the beer and that is one of the causes of over foaming beer served out of a home draft system.
This is why it is so important to maintain the correct temperature recommended for serving the beer that is being dispensed from your home draft system. Highly carbonated beer is in the 2.8–3.0 volume range; nor-mally carbonated beer is in the 2.6–2.8 range; moderate is 2.4.–2.6; low is 2.2–2.4. Very low is 2.0-2.2; really low is 1.8–2.0. The chart above gives you some very basic examples by style for understanding the relationship between temperature and pressure when serving beer.
CO2 volume measures how much CO2 is actually in the beer. The CO2 PSI is the amount of push you need at a given temperature to keep the CO2 that is already in the beer from coming out of the beer. Any more pressure than that and you will have the beer gushing out a little too fast and foaming. Any less pressure and you will have beer that foams at first and then begins to taste flat after the first round of draughts. This is based on the beer being served at the right temperature. These cause and effects rules of thumb are tied to the draft system itself, however, and if you were to modify your draft system you could pour beer with higher carbonation.
For the homebrewer, serving at the ideal temperature is a little complicated. You can’t just call up the brewery and ask them the ideal serving temperature if you are the brewery (although you could geek out next time you visit your favorite brewery and bring along a quick-read thermometer and dip it in your glass of beer to get an idea). It is important that you understand both the relationship between the CO2 volume and temperature and also how to attain that volume of CO2 in your beer. You can carbonate naturally, or, if you either are in a hurry or prefer to work with gas, you can force carbonate your beer. Force carbonation is the process of using CO2 exclusively to attain the CO2 volume you are shooting for in your beer.
Some kegerators are harder to dial in than others. Fortunately, there are many ways to control the temperature of your kegerator, even if the kegerator does not already come with an accurate thermostat built in. There are thermostats available in both mechanical and digital varieties from Johnson Controls and other manufacturers, which are, basically, plug and play units. There are more complicated units as well, such as the Ranco Digital Temperature Controller, which require some wiring in and electrical component ability on the part of the installer.
One often-overlooked aspect of serving beer at the right temperature is the glass that it is served in. There are, of course, many types of beer glasses, from pint glasses to frosty mugs, to specialty glasses, like the interesting goblets used by Chimay. Often, people like to serve beer in a frosty mug, but this is not ideal. It can initially bring down the temperature of the beer past the ideal serving temperature. The best way to store beer glasses is to keep them in a refrigerator, at a temperature that is about the same as the serving temperature of the beer — or just a little colder. Not frozen, only chilled. We will talk a bit more more about glasses later on.
If you want to get the most out of your home draft system and the beer dispensed by it, you should know the ideal serving temperature and CO2 or beer gas push.
Remember that the idea is to maintain the pressure specified at the temperature specified. Too little CO2 gas can be as much of a problem as too much CO2 gas. In the former case, by having too little pressure you are making room for the CO2 already trapped inside the beer-CO2 solution to escape. If you use too much pressure it can also cause the beer to over foam as a result of too much CO2 trying to force its way into the solution.
One book that can help homebrewers to understand how this relationship of pressure and temperature interface with specific recipes for brewing is Brewing Classic Styles by Jamil Zainasheff and John J. Palmer. This book contains 80 recipes for brewing beer that include the volumes of CO2 that should be present in the beer. You can also reference the CO2 pressure chart at http://www.kegerators.com/carbonation-table.php.
A clean beer glass always receives liquid with the least amount of agitation. Make sure your beer glass has been emptied then thoroughly washed, rinsed, sanitized, dried and then rinsed well with cold water before making a pour. The final rinse will remove any residual sanitizer and also bring the glass temperature closer to that of the beer being dispensed. (As I mentioned earlier in this story, do not freeze glassware, as the ice formations lining the glass can cause foaming).
Start with a 45-degree hold on your beer glass and pour along the side, then about halfway through, tilt the glass vertically (see figure at left). You want an inch or so of head at the top of the glass. Allow the beer to settle slightly and top off if necessary. Present the beer to your guest or yourself and savor the flavor.
Make sure to pay close attention to your beer and air-line tube lengths as this can cause foaming issues also.
Pour and Taste
Once you have followed all the steps detailed earlier, it’s time to put your draft system to the test — your taste test, that is. When you have everything reassembled, carbonated and chilled properly, pour yourself a glass of homebrew and see if you have made any improvements on what you were pouring before. If you’ve done everything right it should be a very good glass of beer. If you are careful to keep your kegs at the proper temperature and keep up with regular cleaning and sanitizing of your lines you’ll consistently pour your best beer.