The issue with what you describe is that is it is not how gases interact (although you do acknowledge that the gasses will mix
Quick math on a 5 gallon container with the assumptions of below shows the amount of #'s CO2 and PPM of O2 remaining with a "constant" flush. If you want to ignore all technical publications/books I have found or say that you drink your beer before oxidation effects take place then do so.... however, it can not be said that methods other than vacuum/pressure combination or positive displacement of liquids reduces concentration of 02 to a the range recommended by all technical sources. One of these days I'm going to find a decent dissolved O2 meter for cheap and get some empirical results.
Many people do ignore O2, many people don't control fermentation temp, many people ignore yeast counts, many people do lots of things and still make decent to good beer.
1.standard atmospheric conditions
2.mean free paths are not calculated, gases are assume to mix (this will make the calc slightly conservative)
3.Simplified to multiple small steps to eliminate integration
4.flow rate effects are not considered
5.pressurization of the vessel due to inlet vs discharge flow rates are not considered
hahaha
The drop is rapid...However when I stopped copy pasting iterations I was sitting at .068#'s of CO2 used and >1,500ppm O2 remaining! I of course made some assumptions, and this is likely conservative however illustrates the trend....an open air purge will never get to what I consider an OK oxygen concentration. Pushing sanitizer will use LESS gas and get a much LOWER O2 content with little to no additional effort.
Sources used to teach brewing science such as Brewing Science and Practice are of course more stringent than most homebrewers and assume the finished product should be consistent and have a several month shelf life.
Commercially, piping and fermenters are flushed with nitrogen, alternatively the beer is supersaturated with CO2 during transfer so that when it arrives at the location it is being transferred to it off gasses CO2 itself and displaces the air in the vessel. Or they fill the receiving tank with a deaerated (I don't go this far!!!) liquor that they push out with CO2.
Target for transfer to a brite tank (secondary) is around 50ppm or less. At the end of maturation the target should be <0.01ppm and at packing should be <0.2ppm.
Of course these targets are unreasonable with homebrewing equipment and are exacerbated by the use (sometimes) of pasteurization. However roughly 1ppm is enough to oxidize all reductones in a light beer, of course darker beers will require more and the off flavors will be harder to detect.
Yes I would say ALL brew is oxidized to a point, with MOST homebrew exceeding the commercial recommendations and a Majority of it contributing to off tastes either immediately or over time.
All the dissolved oxygen limits here come from Brewing Science and Practice. Attached are curves made by doug293cz showing the oxygen content of pressure purged vessels.
Beat me to it!
Unfortunately, unless you can squish it, it won't fit. The opening to a corny keg is roughly 4" x 3".
Then there's this one, which will fit:
http://www.amazon.com/dp/B000BU7U0W/?tag=skimlinks_replacement-20
![Craft A Brew - Safale S-04 Dry Yeast - Fermentis - English Ale Dry Yeast - For English and American Ales and Hard Apple Ciders - Ingredients for Home Brewing - Beer Making Supplies - [1 Pack]](https://m.media-amazon.com/images/I/41fVGNh6JfL._SL500_.jpg)
