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Volumes of CO2 are the volume the gas would take up at 0 degrees celcius if it was removed from the beer. So, if you have a bunch of beer carbonated at 2.5 volumes of CO2 (say 10 litres for this example), there is 25 litres of CO2 dissolved in that 10 litres of beer.
This will change with temperature and pressure. CO2 is more soluble at lower temperatures. It is also more soluble at higher pressures. The measurement is volumes of gas. In the above example, if you had 10 gallons of beer carbonated at 2.5 volumes, you'd have 25 gallons of CO2 dissolved in that 10 gallons of beer. I grabbed this picture from a Brewers Association presentation on carbonation. I think it shows what I'm trying to explain.
The full presentation is an interesting read and is located here.
Here is another explanation including a link to a carbonation chart.
Hope that helps.
Cheers!
Chris
This will change with temperature and pressure. CO2 is more soluble at lower temperatures. It is also more soluble at higher pressures. The measurement is volumes of gas. In the above example, if you had 10 gallons of beer carbonated at 2.5 volumes, you'd have 25 gallons of CO2 dissolved in that 10 gallons of beer. I grabbed this picture from a Brewers Association presentation on carbonation. I think it shows what I'm trying to explain.
The full presentation is an interesting read and is located here.
Here is another explanation including a link to a carbonation chart.
Hope that helps.
Cheers!
Chris
Thank you so much for your response so my question now is why don’t containers explode them if you say in 10 gal of beer I have 25 gallons of co2 that’s a lot right ?
No, at 2.5 volumes of CO2 that would be middle of the road carbonation for ales...
CHEERS!
CHEERS!
Because the CO2 is a gas, not a liquid. It's compressed, and some (most)is absorbed into the liquid.
No different in one respect than compressed air.
When the pressure is stable, the pressure in the headspace of a keg will be enough to keep the rest of the CO2 in solution. If you reduce the headspace pressure--or pour the beer in a glass--the CO2 in solution will start coming out. You can see this with the foam head and bubbles rising inside the glass.
Colder beer will allow CO2 to be dissolved into it more readily. That's why if you pour beer into a warm glass, or through a warm faucet or line, it'll foam--as the beer warms, it can't hold the same volume of CO2 as it would if it were colder, so that CO2 comes out of solution.
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Last night I transferred beer from a conical fermenter that was about 8psi at 41 degrees. I chilled the keg into which I transferred that beer, so it wouldn't warm as it entered the keg. I also put on a spunding valve which kept the pressure inside the keg at 10psi as it filled, so the CO2 would be kept in solution and not create foam in the keg.
First of all, you have to remember that this is a gas we are talking about. It's not like you're trying to stuff 35 gallons of liquid into a 10 gallon container. The 25 gallons of gas is compressed and in solution with the beer. There is only 10 gallons of liquid in the keg. If you tried to increase the pressure of the container in order to get more CO2 in your beer, then you run the risk of exceeding the pressure rating of the container. 2.5 volumes of carbonation, as day_trippr has pointed out, is about where an ale should be. A lambic could benefit from around 3 volumes. An English ESB 1.5 to 2 vols.
And mongoose33 beat me to it. ;-)
Matthew Nelson
Member
When CO2 dissolves into the beer each molecule is suspending by the surrounding water molecules. It is very similar to dissolving sugar or salt into water. The only difference is at the volumes of CO2 we need to create the effervescent bubbles we recognize as carbonation, requires pressures greater than atmosphere. When 2.5 volumes of CO2 is dissolved into the beer it becomes more dense and occupies less space. But if it were taken out of solution and back to it's gaseous form, it would fill 2 and a half times the volume of liquid at benchmark temperature and pressure.
To give you the full geek explanation: 1 volume of carbonation is when the CO2 dissolved in the beer would occupy the same volume as the beer if removed from the beer, with the gaseous CO2 being at STP (Standard Temperature and Pressure, which is 0°C [32°F] at 1 atmosphere of pressure [14.695 psi].) For 2 volumes the CO2 would occupy twice the volume as the beer occupies. And so forth. So volumes are equivalent to liters/liter, gals/gal, etc. Now 1 liter of CO2 at STP has a mass of 1.9768 grams. So a volume of CO2 is also equal to 1.9768 g of CO2 dissolved in 1 liter of beer. If you want to do calculations with CO2 in beer, this is handy to know, but for just carbonating your beer you don't have to worry about it.
The equilibrium volumes of carbonation is dependent on the temperature of the beer and the partial pressure of CO2 above the beer. The partial pressure is the pressure that the CO2 would exert if no other gases were present in the headspace. For pure CO2 in the headspace at 0 gauge pressure, the partial pressure is 14.695 psi (since gauge pressure is the absolute pressure - atmospheric pressure.) The well known carbonation/temp/pressure tables tell you how many volumes of carbonation the beer will have when in equilibrium with the CO2 in the headspace at various combinations of temperature and gauge pressure.
Brew on
The equilibrium volumes of carbonation is dependent on the temperature of the beer and the partial pressure of CO2 above the beer. The partial pressure is the pressure that the CO2 would exert if no other gases were present in the headspace. For pure CO2 in the headspace at 0 gauge pressure, the partial pressure is 14.695 psi (since gauge pressure is the absolute pressure - atmospheric pressure.) The well known carbonation/temp/pressure tables tell you how many volumes of carbonation the beer will have when in equilibrium with the CO2 in the headspace at various combinations of temperature and gauge pressure.
Brew on
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The posts above explain why the containers don't explode. But be aware that if you get too much carbonation, the container (bottles in particular) can explode. Don't ask me how I know.
