Once you start using kegs at home, it becomes abundantly clear that you need to follow some guidelines to ensure that foaming does not become a problem. Especially if you are modifying your kegerator to accommodate more than one keg, it is important to pay close attention to your beer line length, CO2 gas line length, temperature, and the ideal push for each type of beer that you will be dispensing.
Tube lengths being off as little as a foot or as little as 2 PSI of pressure can alter the taste and texture of the beer being served.
If you are off by as little as 2PSI of pressure, it can alter the taste and texture of the beer being served. Here are a few tips that can help you to have the nice tasting draughts that you would get at the pub at home.
Becoming familiar with how the carbonation process works is a good start. Realize that the ideal temperature and pressure will be dictated by the type of beer being dispensed. Also, the length of your beer line, and the length of your CO2 gas line will have an affect on the resultant qualities of the pour.
First of all, it is a good idea to be familiar with the way carbonation affects the taste of beer, in all its varieties. Generally, the less complex the taste, the more bubbles you want to put into the beer to balance our the final taste.
A rich malty and hoppy beer needs as little as 7 PSI of pressure behind it, while for a light lager style beer, you will usually want something like 15 PSI to push it properly. This is why it is necessary to have a CO2 manifold capable of pushing gas at different pressures, if you wish to serve various beers of different types at once through your home draft system.
Temperature also greatly affects the amount of CO2 gas that is absorbed into the liquid beer. The lower the temperature, the more easily the beer accepts CO2, and the higher the temperature, the more difficult it is to introduce CO2 into the beer.
A useful rule of thumb
This is why it is imperative that you determine or discover what the ideal temperature and CO2 pressure is for the beer that you are serving. [CO2 Pressure Chart]
Say you are having a huge football party at your house, and you decide that everyone is going to pitch in to get a keg of Bud. This beer is ideally served at 45 degrees Fahrenheit at 12 PSI. Your kegerator runs a little colder than that, and has chilled the beer to 41 degrees. Since more CO2 is being absorbed by the beer at this temperature, you need to adjust your CO2 pressure down by 2 PSI, and push the beer at a total of 10 PSI.
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" ID (inner diameter), 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, 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 .5 pounds per foot of rise or fall of additional restriction.
An old-timer told me this rule for determining the beer line length: You take the ideal pressure, add five, and then divide by the beer line's restriction value per foot. He used to work on installing draft systems commercially, and I have found his rule of thumb to be useful. He also said that 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.
Lets apply this rule of thumb to a specific situation. Say we have the exact situation as above, except that now the party has become a regular thing and the master of ceremonies wishes to make sure that his home draft system has an ideal length for dispensing Budweiser. He has adjusted the temperature of the kegerator so that it matches the 45 degree Fahrenheit manufacturer recommended serving temperature. Now, he is serving at 12 PSI, and has discovered that the type of beer line used in his home draft system has a restriction value of 2.0 pounds per foot. There is a 2 foot rise in the beer line as well. So, to calculate the ideal beer line length, we take 12 from the ideal pressure, add 5 (arbitrary number), and divide by 3 (2 for the beer line's restriction value, and plus 1 for the rise). We get a result of roughly 5' 11/16th ". So the master of ceremonies cuts down his beer line from 6'5" to the new length, and the beer tastes as good as its going to get.
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 above, 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.
Related Kegerator Articles :
Dialing-In your Home Draft System: Modifying a Draft Tower -- Learn how a few quick modifications tips from Kegerators.com on your draft tower can allow for additional faucets.
Dialing in Your Home Draft System's Temperature -- Kegerator foaming? Loosing beer each time you pour? You may not have your temperatures set properly for the amount of CO2 in the beer being dispensed.
CO2 Carbonation Chart -- Handy-Dandy Slow Force Carbonation Chart featuring Pressure vs. Temperature in Degrees Fahrenheit.