# Homebrewers Association | AHA Forum

## General Category => Kegging and Bottling => Topic started by: monomer77 on November 27, 2010, 03:20:06 PM

Title: Co2 Escape
Post by: monomer77 on November 27, 2010, 03:20:06 PM
How fast does CO2 escape from a container. Like if a bottle or keg is filled with CO2, will it immediately escape right out the hole when it's opened?
Title: Re: Co2 Escape
Post by: tom on November 27, 2010, 05:16:26 PM
Good question. Gases diffuse to fill their space - that's part of the definition of a gas.
It depends on the opening and I'm sure there's all sorts of diffusion coefficients involved.
So it will diffuse out (and outside gases in), but not immediately.
Title: Re: Co2 Escape
Post by: oscarvan on November 27, 2010, 08:55:55 PM
I would think that it is a function of pressure and the size of the hole....
Title: Re: Co2 Escape
Post by: monomer77 on December 04, 2010, 02:38:51 PM
Let's say it's a carboy filled up. Once the bung is pulled out, does the gas jump right out?
Title: Re: Co2 Escape
Post by: oscarvan on December 04, 2010, 03:20:12 PM
OK, it's not pressurized...... No. CO2 is heavier than air and will "sit" in the carboy if not disturbed too much. If you put a hole in the bottom it will flow out.
Title: Re: Co2 Escape
Post by: Steve on December 04, 2010, 03:38:22 PM
Yes CO2 is heavier than O2.  The proof is seen when you place dry ice, which is frozen solid CO2, into a container of water, the dry ice will "boil" turning from a solid into a gas.  The gas which is seen as a fog (as in many horror films: the bubbling potion with fog flowing out on Dr Jeckyl's desk or as fog in a cemetery laying low on the dirt) will flow over the container's side and will flow down to the lowest point such as the floor.  Eventually the CO2 gas will expand and dissipate into the room and the fog will disappear.

So – yes the CO2 will remain in the carboy neck for a bit of time but will want to expand to fill the room.  I don't know exactly how long the CO2 remains there.  I do know from using dry ice fog in theatrical situations, that the CO2 fog will dissipate, if it is not replaced, in about 2 minutes
Title: Re: Co2 Escape
Post by: tom on December 04, 2010, 06:53:53 PM
OK, it's not pressurized...... No. CO2 is heavier than air and will "sit" in the carboy if not disturbed too much. If you put a hole in the bottom it will flow out.
Not as long as CO2 is in the gas form. Gases diffuse to fill their space. That is a basic definition of a gas.

Good for me because I ferment, carbonate, and serve carbonated beer in my basement and it would have filled with CO2 long ago.

As Steve notes above " yes the CO2 will expand to fill the room".

Of course there are time and temperature constants involved.
Title: Re: Co2 Escape
Post by: richardt on December 04, 2010, 07:00:01 PM
Your basement, just like any other room or theater, probably has a cold air return that helps remove cold air (and CO2) from your basement.
Title: Re: Co2 Escape
Post by: tom on December 04, 2010, 07:18:35 PM
Nope. (We don't open the windows either.) Our house is over 100 years old.
Just basic science.
Title: Re: Co2 Escape
Post by: oscarvan on December 05, 2010, 02:35:16 AM
OK, it's not pressurized...... No. CO2 is heavier than air and will "sit" in the carboy if not disturbed too much. If you put a hole in the bottom it will flow out.
Not as long as CO2 is in the gas form. Gases diffuse to fill their space. That is a basic definition of a gas.

Good for me because I ferment, carbonate, and serve carbonated beer in my basement and it would have filled with CO2 long ago.

As Steve notes above " yes the CO2 will expand to fill the room".

Of course there are time and temperature constants involved.

Yes, I should have specified that slowly the gas will work it's way out of the hole.....