Watching a Guinness stout clone homebrew after a pour ... I noticed a line of CO2 bubbles form at the bottom of the glass. So I looked up - which is a heavier gas, CO2 or Nitrogen? Then I did the same for O2. And guess what, CO2 is heavier by far than either oxygen or nitrogen.
Before I did O2 free transfers using corny keg posts, I just carefully dropped a tube into the bottom of a corny keg, and pushed a little CO2 into it to clear out any O2. While not perfect (might be a little churning of gases... But who knows??) I never had a problem with O2 spoiling the beer. I used this method so many times and it always worked fine.
Doing the O2 free transfer can be soooo slow, and also "blind" since I have no idea how much is in the corny other than guess by weight. So, I think I am just going back to my old method... Just carefully fill the corny with beer from the bottom up and purge with CO2 from time to time. I place saran wrap over the lid and just leave enough room for the tube to go in, and let out gas.
Anyway... I think most people, myself included... Get a little paranoid with O2 infiltration at racking... If you are careful it can be done well without all the fuss. CO2 sinks... And is heavier than O2. So ... Slow movements, keep the gas area as still as possible, fill , bottom up and down a purge of CO2 from time to time. My own experience is - you will be fine.
Before I did O2 free transfers using corny keg posts, I just carefully dropped a tube into the bottom of a corny keg, and pushed a little CO2 into it to clear out any O2. While not perfect (might be a little churning of gases... But who knows??) I never had a problem with O2 spoiling the beer. I used this method so many times and it always worked fine.
Doing the O2 free transfer can be soooo slow, and also "blind" since I have no idea how much is in the corny other than guess by weight. So, I think I am just going back to my old method... Just carefully fill the corny with beer from the bottom up and purge with CO2 from time to time. I place saran wrap over the lid and just leave enough room for the tube to go in, and let out gas.
Anyway... I think most people, myself included... Get a little paranoid with O2 infiltration at racking... If you are careful it can be done well without all the fuss. CO2 sinks... And is heavier than O2. So ... Slow movements, keep the gas area as still as possible, fill , bottom up and down a purge of CO2 from time to time. My own experience is - you will be fine.