Procedure for carbonating naturally in Corny

I'm know this has been asked many times but I can't find the answer.

My kegerator only has room for one keg, so rather than force carbing I was planning on naturally carbonating the other kegs in the pipeline so that when the keg on tap runs out I can just swap it out for a new keg.

Question: when adding corn sugar to the corny should I leave the air in the keg? Presumably the yeast needs the O2 to eat the sugar to carbonate? Then after 3 weeks at room temperature, blast it with CO2 and vent to remove any air so that it can be stored for a few months? Sound reasonable?

I naturally carb my kegs when the pipeline's full enough. My procedure looks like this:

Add sugar to sanitized keg, rack beer onto sugar. Close keg, purge headspace 3-5 times with CO2, ignore the keg for a few weeks.

You don't need to leave air in the headspace to get the yeast to consume the priming sugar. Also, I've primed several kegs where I forgot to purge the headspace, without ill effects.

spiny_norman said:

Question: when adding corn sugar to the corny should I leave the air in the keg? Presumably the yeast needs the O2 to eat the sugar to carbonate?

Click to expand...

No. Yeast use O2 mainly while dividing, which isn't something that's wanted/needed in the bottle or keg. As long as the yeast are healthy, they shouldn't need any more oxygen. Most of your fermentation is done anaerobically.

no matter what, purge the keg.

*BUT*, i don't leave my kegs hooked up to co2.
I mounted a bike tire valve on a gas-in fitting. 4 to 4.5 gals gives me enough headroom.
foosh it (with a tire inflator valve) up to about 20 psi.

I use air compressor QD's (300psi max) on my gas lines, so I can hook/unhook in 1.358 seconds.

natural carb if you like, but there's no reason that you have to.

you can see why i have to do that, here:
https://cdn.homebrewtalk.com/gallery/showphoto.php?photo=31732&cat=all&ppuser=37840

I pressure-test the keg before racking beer into it. Then I poor the priming sugar in, add the beer and close it up (by pressurizing to 20 psi). CO2 is heavier than air, so it should remain in the keg from pressure-testing.

My question is this: how much priming sugar are people using? I hear so many different things, and everybody thinks their way works.