Force Carbonating your Home Brew
Carbonating your home-made beer can be a little tricky. This handy carbonation table lists PSI (Pressure per Square Inch) against keg temperature to give you a quick reference guide for carbonating you ales over a three to five day period. This slow forced-carbonation process is the best suited for having foam-free home brew. This chart is color coded to reflect low, mid, and high levels of bubbliness, according to beer type (see key below). There is a faster method for force carbonating ale, however, the quick method tends to make the beer over-foam when first tapped. We will discuss both methods.
When utilizing the "Handy-Dandy Slow-Forced Carbonation Table featuring Pressure vs. Temperature in Degrees Fahrenheit", first consider the level of carbonation desired in the home brew you are making. Most brewers have a preference on either side of the standard carbonation levels, so use the lower side of PSI if you prefer a smoother ale, and the higher side if you prefer a bubblier brew. This table shows different volumes of CO2, based on the following ratio: 1 portion of beer containing 1 portion of CO2 is 1 volume CO2, and 1 portion of beer containing 3 portions of CO2 is considered 3 volumes.
Practically speaking, 1 volume of CO2 is too little for most tastes (blue region), and 4 volumes is too much (red region). Stouts and porters are on the lower side (dark region), ambers, lagers, and most other beers fall in the middle (green) region, with lambics and other brightly effervescent ales rounding out the higher levels of carbonation (the yellow region).
CO2 always infuses into beer more effectively at lower temperatures. Since most kegerators operate at a level of 30 to 40 degrees Fahrenheit, you will notice that the CO2 volumes on the green region are emboldened and italicized. This is to help draw your eye to the area of the table that you will most likely be using for force-carbonating most ales.
The quicker method of forced carbonation, is best saved for emergencies where you need to get beer ready fast. By really fast, I mean 'overnight instead of 3-5 days', not 'a few hours', although you can probably get by with 5 hours if you modify the technique slightly. The 'quick and dirty' method requires you to have an extra long gas line going to your keg. Also, you must chill your keg as much as possible. The idea is that by stirring the solution of CO2 and beer, the two elements will mix more readily. After chilling your keg, hook up the CO2 and pump the regulator up to about 30 PSI.
Now, lay the keg on the deck and roll it back and forth. Make sure that your CO2 bottle is secure and won't tip over. You will hear more and more CO2 entering into the solution as you agitate it. Do this for about 2-3 minutes, then disconnect the CO2 and let the keg sit and the CO2 settle down into the mixture as it is chilled once again. One to two hours later, go back to the keg and let off the excess pressure. Reduce the pressure to the proper amount of PSI for the beer you are kegging, according to the "Handy-Dandy Slow-Forced Carbonation Table featuring Pressure vs. Temperature in Degrees Fahrenheit". Let the beer settle now, overnight, in a chilled location. In the morning, the beer should be ready to drink.
If you are in a real rush to drink your brew (i.e., you can't reschedule the wedding reception/bachelor party for later), you will have foam trouble, but you can still use the 'quick and dirty' method. You will still have to chill the keg of beer both before and after you apply the technique - by lowering the high pressure of the CO2 during mixing to about 23 PSI, you will improve your chances regarding over foaming. Try and make sure it has at least 3 hours to settle, though. One hour after the forced mixing, and two hours after the pressure normalization.