Most homebrewers start with bottle carbonation, but at some point, many get tired of washing bottles. That's when kegs come into play, and the time has come to switch to Cornelius kegs. The advantages of Cornelius kegs are numerous, and we will now delve deeper into them. How keg carbonation works in practice is also an interesting aspect in this context.
Cornelius kegs - the practical solution for homebrewers!
There are several types of kegs, such as disposable kegs from PolyKeg and KeyKeg, which are mostly used by professional breweries. For homebrewers, Cornelius kegs are the most common. These are made of steel, which means they can withstand both rough handling and chemicals. They come in several sizes and can be reused almost indefinitely:
- Less work with cleaning, bottling, and storage.
- Less oxygen in the beer, better quality, and shelf life.
- Ability to connect to a tap or draft tower.
- Beer becomes drinkable faster.
- More control over carbonation level.
To get started, you need more than just the keg itself. This includes a pressurized CO2 cylinder, a regulator to adjust the pressure into the keg, as well as hoses and fittings for this. To make this very simple, we recommend a Cornelius keg package which includes everything you need to get started with carbonating beer in a keg.
It should still be mentioned that it is possible to fill bottles or cans with pre-carbonated beer. In that case, we recommend using a Beergun, Tapcooler, Pegas, or similar solutions.
Cornelius kegs were originally designed for Coca-Cola and Pepsi essences but are now mostly used by homebrewers worldwide. These were originally manufactured by Cornelius and AEB, among others, and these are the same kegs we still carry. The largest keg was originally 5 gallons (18.9 liters), but because Norwegian and European homebrew batches are larger than the American standard of 5 gallons, we have had 20L Cornelius kegs developed by AEB. We also carry 23L Cornelius kegs, which offer enough space for an entire 25L batch after fermentation. We believe this is the ultimate size if you are unsure which keg to buy.
Below you can see an example of a "keezer," a freezer full of Cornelius kegs and temperature-controlled by, for example, an Inkbird temperature controller.
Read more about choosing a dispensing system and taps in our related blog post on dispensing beer from kegs.
Cleaning Cornelius Kegs
When you get a new keg, or when you have emptied a keg, it should be washed before use. For this, warm water with a suitable detergent and a good scrubbing brush are recommended. A good aid that makes the job even easier, especially if you have several kegs, is Marks Keg Washer or FastWasher Rack. For new kegs, or kegs that are not very dirty, Chemipro Oxi is recommended. This is a detergent that also disinfects. Therefore, it does not need to be rinsed out after use. For dirtier kegs, we recommend PBW instead.
Once the keg is clean, it must also be sanitized in the same way as bottles, for example with Saniclean, which foams much less than, for example, Star San.
Purging and oxygen-free transfer of beer
Beer is vulnerable to oxygen. If there is too much oxygen, it will darken, taste less, and often have an unpleasant cardboard aroma. All types of beer can be damaged by too much oxygen, and highly hopped beers are particularly vulnerable.
There are many solutions to avoid oxygen in the keg, and an entire article could be written about this alone. The simplest thing to do is to pressurize the keg and pull the pressure relief valve a few times. This will force much of the oxygen out of the keg, replacing it with CO2. This should be done both before and after you fill beer into the keg to minimize oxygen.
How to transfer beer to a keg
Once the keg is clean and sanitized, it's ready for beer. Here too, there are several methods for how to do it. We choose to describe the simplest method for you:
- Use a siphon with a hose, or connect a hose to the tap on your fermenter if you have one. Remember to sanitize the siphon/tap and hose first.
- Place the hose all the way to the bottom of the Cornelius keg to minimize splashing, which can introduce air. At the bottom of the keg, there is also a blanket of CO2 after purging before filling, which provides decent protection against oxygen.
- Now you can transfer the beer to the keg. Once the beer is transferred, put on the lid (remember to sanitize this too).
- It can be tricky to get the lid sealed. We therefore recommend Keg Lube as an aid. It also lubricates the O-ring so that it lasts longer and avoids cracks.
- When you then apply pressure, the lubrication from Keg Lube will help to seal it all.
- The Cornelius keg is marked with "in" on the rubber handle, so it should be easy to find the correct port.
Closed transfer to Cornelius keg
Alternatively, we can perform a closed transfer. This means that the beer does not come into contact with air on its way to the Cornelius keg, significantly reducing oxygen ingress. Again, there are several methods to achieve this, but the principle is the same: Connect a hose to the tap on the fermenter and place the other end on the outlet (black connector) of a sanitized and purged keg without pressure. Open the pressure relief valve so that no pressure builds up in the keg during the process. It can also be wise to use a scale to see how much you are filling, so that you don't overfill the keg, or in the worst case, it overflows. If the beer is cold, you will be able to see condensation forming on the outside of the keg, and use this as an indicator of how much has been transferred.
It is not recommended to fill more than to the dip tube for CO2 (the short tube at the very top of the keg). This is to prevent the beer from flowing back into the regulator if there should be a pressure change, for example, if the CO2 tank runs out. If you still want to fill the keg completely, there are also safety solutions for this, such as a check valve or a ball lock with built-in check valve.
Carbonating beer in a Cornelius keg
To carbonate beer, there are two methods we can use. One is similar to natural carbonation in bottles, where we add sugar and let it sit at room temperature for a couple of weeks. This method is perfectly viable, but once we have pressurized CO2, there is a simpler and more practical method: forced carbonation. Forced carbonation can be done in several ways, but the safest method for a good result is to use a carbonation chart.
To make it easy, you can use the following solution: Set 1 BAR pressure into the keg, keep it there for 1 week, at refrigerator temperature of about 3-5 degrees Celsius. Here, most beers will achieve a good carbonation level. The gas should be connected and on all the time. As long as the pressure is not increased, or the temperature in the keg does not rise, the beer will become saturated and will never have more carbonation than the pressure you have set.
Interpreting the carbonation chart
To pinpoint the carbonation perfectly, we recommend using the table below. This can be a bit confusing the first time you look at it, but it can be read in this way:
At the top, PSI and BAR are stated. These are two different units of measurement for pressure. Most regulators will state both. In Norway, we normally state BAR as the unit.
On the left side, temperatures are given. The lower the temperature of the beer, the easier it absorbs CO2/carbonation. Therefore, we can use this table to pinpoint exactly what temperature and pressure we want to use to achieve the desired volume. Volume is a unit that describes how much carbonation is in a beer. At the bottom of the list, color codes are given that show recommended volumes for most beer styles.
With this information, it should then be possible to choose exactly how much carbonation suits your beer.
Use a carbonation calculator
Let's take an example: You have brewed an IPA. It falls under Ale, and should be carbonated to the green level in the table. You have a refrigerator that maintains a steady 4 degrees Celsius. From the table, we can see that you should set the pressure into the keg to between 0.62 and 0.83 BAR. Anything between these two values will be correct for the style, but higher pressure gives more carbonation. This is simply a matter of your own taste.
Regardless of which pressure and temperature you choose, this should remain for about a week before it is ready.
There are also smart solutions that can quickly carbonate your beer in a short time, such as Blichmann QuickCarb. It will automate the process for you and can carbonate a keg of beer in about one hour.
Other carbonation methods include 3 BAR for 24 hours, or 2 BAR at 2 degrees for 48 hours. Some also choose 3 bar and vigorously roll or shake the keg for a few minutes. These methods are generally not recommended if it's your first time using a keg. They should be used with caution, as the risk is that the beer may become over-carbonated: meaning too much carbonation and, in the worst case, only foam. A lot of sediment will also be stirred up, which not only makes the beer cloudy but can also affect the taste.
My beer is carbonated, now what?
If you have followed the table and carbonated correctly, your beer is ready to drink after about a week. All you need to do now is connect the tap line to pour yourself a nice beer. Keep the pressure at the same level you carbonated with, as this is usually the best serving pressure. If you want even more carbonation, you can increase the pressure according to the table and let it sit for a while longer.
Remember that most beer styles should mature for a period to achieve their optimal flavor. Even if fermentation is complete and the beer is carbonated, it may not be at its best yet.
Why is only foam coming out of the tap?
If you have a beer that requires heavy carbonation (wheat beer or sour beer, which can often be more heavily carbonated), you may experience problems with foam. This can be solved in several ways. The simplest is to use a tap line with a thin hose, also called a foam-reducing hose. This is thinner, so you get more resistance during tapping. This reduces the risk of foam. It can also help if you use a longer hose, as length provides more resistance in the same way a thinner hose does.
If something has already gone wrong, the beer may be over-carbonated. This can be a result of the pressure being too high, or the beer being too cold. In that case, other tap lines may not solve the problem. In addition to foam problems, the beer you get will be "stinging" and unpleasant to drink. It can actually become completely flat if all the carbonation disappears into foam.
To solve this, disconnect the gas and pull the safety valve located in the lid of the keg until all pressure is gone. Shake the keg a bit so the beer releases carbonation. Wait a while until the foam settles and release the pressure again. This must be repeated until you get the carbonation level you desire.
If this doesn't help, you can check if all hoses are properly seated in, for example, John Guest quick connectors, etc. A microscopic opening between the hose and the quick connector is enough for oxygen to be drawn into the tap line, causing foam when you tap. Cut the hose ends and reconnect them, and it might improve.
If none of the above helps, it could also be that the dip tube in the Cornelius keg has become clogged with, for example, hop residue. In that case, you can try to blow it clear by connecting CO2 to the beer out valve.
How do I fill beer into bottles or cans?
Many people like to share their beer with others or take it with them on a trip. There are several smart solutions for this. If it's a small amount to be consumed the same evening, it can be poured into a bottle with a tap, but the risk here is that the beer can lose a lot of carbonation. It's also not a good solution if it's going to be in a bottle/can for a longer period. If it's going to be stored for a long time, the Blichmann BeerGun is specially designed to transfer keg-carbonated beer without losing carbonation and minimizing oxygen. Other alternatives are counter-pressure fillers like TapCooler or PEGAS. An automatic can filler like DuoFiller is highly recommended if you are going to can larger quantities of carbonated beer.
