Finding the right CO2 tank for your home draft needs requires some consideration. Some of the factors included in your decision should be portability, efficiency, and space considerations. CO2 tanks come in a variety of sizes, usually from 2.5 lb to 20 lbs. Most CO2 tanks for homebrewing purposes are made from aluminum, but there are steel tanks available as well, and what type of tank you have will somewhat affect the taste of your beer. Your guide to C02 tanks begins with a simple consideration: a basic understanding of the nature of compressed gases.
Compressed gases such as carbon dioxide, oxygen, and nitrous oxide are all gases at room temperature. But get them cold enough, and they become liquid. Get them colder still, and they will become solid - and more concentrated or dense. As these compounds increase in temperature, they also expand in volume. Your CO2 tank is the same way - the pressure increases the hotter the tank (and therefore the CO2 inside) gets. This is why it is important have a good CO2 regulator and keep your tank from heating up drastically.
CO2 expands rapidly as the tank's temperature increases, putting more and more pressure on the gas regulator which controls the CO2 output. The CO2 that the tank has been filled with is very cold (between -57 and -78 degrees degrees). At that temperature, the CO2 puts out only 100 PSI (pounds per square inch). At room temperature (70 degrees), the tank puts out about 850 PSI, and at hot temperatures (around 110 Degrees), the tank can put out a whopping 2000 PSI. If your tanks are ever in the position to be raised to that high of a temperature, the release valve will be triggered to prevent the tank from exploding. This can be quite startling, so it is wise to take steps to avoid this by storing your tank in a cool place, even while disconnected. This is why CO2 tanks are filled to only 34% of their volume. If the tank is filled more, it can trigger the safety and let all the gas out if it is exposed to high temperatures.
Keep in mind that compressed gas tanks like the CO2 tank are powerful tools. Tools like this need to be treated with respect. So, if you are planning on having tanks like these around, follow proper safety guidelines. Do not turn the regulator pressure up higher than recommended, and make sure your tank is always standing upright when in use. Needless to say, keep out of reach of children.
The first thing you should consider when looking at getting your draft beer system going is how much room you have for your CO2 tank. Keeping your CO2 canister and your beer keg cold will greatly help with the quality of your beer carbonation. The primary reason for this is that CO2 will infuse into your beer much more efficiently at lower temperatures.
Having enough room in your kegerator for your CO2 tank will ensure that your beer does not grow too foamy and will allow you to keep a firmer control on the carbonation present. So, if you have a full-sized kegerator setup, you have room to keep a large tank cool. For smaller kegerators, you should go with a 10 lb at most. Visiting you local home brew or kegerator supply shop will help you get a grasp on the dimensions you are dealing with.
Another consideration is the size of the beer keg that you will be using. Most home brewers use Cornelius kegs, which are quite slim. If you are planning to use regular beer kegs, you will probably have to have an external CO2 tank unless you have a full-sized kegerator conversion from a refrigerator. The bigger sizes of home-use CO2 tanks are the easiest for most people to deal with, because they require filling less often. A good middle-level CO2 tank is the 15 pound capacity tank. This will fit inside most kegerators, and carries enough gas to carbonate a couple hundred gallons of beer.