I posted an unproven theory of mine in another thread. That theory was that if I filled a new keg with CO2 that the CO2 might settle to the bottom in a few hours and then push more of the O2 out the top when I purged. Another poster made the point that gases mix very quickly and so this theory has no merit. You can find the conversation starting on post 9 here:
https://www.homebrewtalk.com/f35/transporting-kegs-395265/
This conversation got me thinking.
I know gases mix easily in open environments because of currents and convection. Any movement in an environment will facilitate mixing. Is this the case in a closed environment like a keg or fermentor? In a fermentor there are yeast producing CO2 during fermentation and the beer is off-gassing afterwards, so there is bound to be some type of convection going on for quite a while I would think. If that is the case and I displace some of that CO2 with a wine thief then the air that replaces it will mix very quickly with the CO2 in the headspace.
I have always thought of the CO2 in a fermentor or keg as a protective blanket or layer. If any introduced air is quickly mixed with this layer then it isn't a protective blanket at all. I have been browsing the web for a while trying to find research to back up either side of this argument and so far it looks like stratification of gases is pretty difficult to obtain to any meaningful degree unless you have a very tall column of gas (much taller than we are talking about with brewing equipment).
I was hoping to get input from others on this subject and hopefully come to a conclusion one way or another.
https://www.homebrewtalk.com/f35/transporting-kegs-395265/
This conversation got me thinking.
I know gases mix easily in open environments because of currents and convection. Any movement in an environment will facilitate mixing. Is this the case in a closed environment like a keg or fermentor? In a fermentor there are yeast producing CO2 during fermentation and the beer is off-gassing afterwards, so there is bound to be some type of convection going on for quite a while I would think. If that is the case and I displace some of that CO2 with a wine thief then the air that replaces it will mix very quickly with the CO2 in the headspace.
I have always thought of the CO2 in a fermentor or keg as a protective blanket or layer. If any introduced air is quickly mixed with this layer then it isn't a protective blanket at all. I have been browsing the web for a while trying to find research to back up either side of this argument and so far it looks like stratification of gases is pretty difficult to obtain to any meaningful degree unless you have a very tall column of gas (much taller than we are talking about with brewing equipment).
I was hoping to get input from others on this subject and hopefully come to a conclusion one way or another.