Keg headspace

[lawpaw]

I have searched for this, but couldn't find anything.

Can I keg 4 or 4.5 gallons in a 5 gallon keg? Of course I would purge, but I can't imagine that getting all the O2 out.

What if I want to force carb 4 gallons for bottling from a 5 gallon keg? Would it be a huge waste?

 

[dbrewski]

yes you can put 4 or 4.5 gal in a corny. Purge and let it sit for two weeks at serving pressure it will be fine.

I would watch burst carbing, because there is an effect of the amount of headspace of CO2 you have - the increased headspace might result in higher CO2 absorbption, so many of the techniques might produce different results (ie. shaking the keg for 100 sec. at 30 psi, which does work, might overcarb in this case). Just my 2 cents.

 

[lawpaw]

Would it be better to find something gallon sized and pressure proof that I can sanitize and put in there?

 

[maffewl]

Would it be better to find something gallon sized and pressure proof that I can sanitize and put in there?

Nah... just purge and keg. Set and forget. I guess you could sanitize a bunch of glass marbles (or some other space filler) if you wanted to, but I don't see the point.

 

[wildwest450]

Would you dump a full keg after you drank a gallon or two out of it?

 

[lawpaw]

No, but I'd be more comfortable that very little O2 was in there since it was sealed full.

I'm not confident purging pushes out all the O2 out. I realize theoretically it should, but in real world application the air may mix quite a bit during purging. 1 gallon could have a good deal of O2 in it, I don't know.

 

[dbrewski]

when I rack into a corny, I blast it with CO2, right in the open top. CO2 is heavier than air and forms a blanket on the bottom. It also rises with the beer and pushes the air out. That way the beer never sees much O2. The purge is just to make sure.

 

[mcgearybrewing]

when I rack into a corny, I blast it with CO2, right in the open top. CO2 is heavier than air and forms a blanket on the bottom. It also rises with the beer and pushes the air out. That way the beer never sees much O2. The purge is just to make sure.

That's the way I've been doing it for 11 years and have never had any issues with O, even if I only end up with 3.5G going into the bright tank...

 

[david_42]

Heck, I've put as little as 2 gallons in a cornie without a problem.

 

[lawpaw]

Thanks guys, I knew that C02 should form a blanket, but was unsure if there would be any air mixing dynamics that would affect that in the real world.

Glad to hear you all don't have trouble with it.