Metal or bag barrels? Push with CO2 or air?
Surely we have already seen or heard more than once on blogs or chatting with brewers, about types of barrels, characteristics, etc. So I am going to focus on something more specific, such asbeer back pressure in kegs and especially when using air or CO2.
The most widespread system or product is CO2 or carbon dioxide, mainly it fulfills two functions within a beer barrel, which would be topush beer or other liquids, and also keep the atmosphere of the carbonated keg and prevent it from decarbonating.
Thereforewe could never use air to back pressure a barrel unless it's a barrel with a bag. But, there are barrels in which you can put normal air and there is no need to use CO22?
Yes, this type of barrel has a bag inside, which is where the liquid is deposited and unlike the typical metal barrel,the incoming gas is not in contact with the beer so withan air compressor might be enough to push the beer and, therefore, it would not be necessary to go buying CO2 bottles. The system is similar to a Bag in Box.”.
The main differences between these two barrels are cost issues, on the one hand,bag barrels are typically disposable and single use so the cost could be higher with the naked eye, but on the other hand, the metal barrels must take into account that apart from buying CO2, you will have to clean them one by one to reuse it again, so all this also takes time and money , in addition to the transport costs of collecting the barrel.
Non-reusable bag barrels have helped a lot especially in theshipment of the product to different parts of the world since it has allowed the sale internationally of the beer and not worrying about the return of the container, it is simply sent and they forget that part.
¿So, what would happen if I counterpress a barrel that does not have a bag with an air compressor? For nothing to happen, the air will counterpress the same and you will get the same beer. So, well, firstly because of a health issue it could no longer be done if you sell it to the public because you contaminate the beer and then, as we have previously commented, that beerza it will decarbonise in a short time and rust Since we must not forget that we are counterpressing the air of the place where we are, we are not injecting CO2 into the barrel, let's imagine that the contamination of the environment in that place is quite high, we will be putting all that into the barrel, the rest already it is evident, flavors, defects, smells…
So we could never use air to backpress a keg unless it is a keg with a bag and is not in contact with the beer.