briefly opening a half full keg

[RedlegEd]

Heh - Haven't done it yet. I'm stuck on a different aspect of this problem, which is figuring out exactly how to make the acid adjustment that I want first.
What I've decided to do is to push a couple psi of CO2 through the liquid post for the few seconds it'll take me to pour a 1/4 cup into the keg. I figure that'll hold back any O2 trying to sneak its way in. Probably purge a couple times anyway just because.
I'll report back when it's a done deal.

Just a thought, but if you aren't adding more than a few ml of acid to the keg, why not disconnect the CO2 line, fill it with the amount of acid needed, then hook it back to the gas and let the CO2 inject it straight into the keg? Ed

 

[day_trippr]

Digging through that thread now, but what's the purpose of the balloons?

I've seen people use balloons to keep the pressure up when cold crashing, but not like this.

Think of the balloons as pneumatic fuses.
If something goes FUBAR at the regulator, I won't have 11 gallons of shattered glass and lost beer in my ferm fridge (and all over the floor)...

Cheers!

 

[55x11]

I don't think the solid bung/stopper would work well on a bucket just because the lid seals are so bad. It could work on the PET vessels I have now, but I don't know how much negative pressure they can take before collapsing. I don't think I'm curious enough to test one to failure, cause they're not cheap.

Brew on

I agree with Doug, Matt - you might as well keep your fermenter open and let air in as you are cold crashing - at least it prevents your fermenter from breaking (if glass) or collapsing (if PET) - once you open your solid bung, air gets in, if it didn't get in already (which I think is more likely - in my experience buckets are always leaking around the lid area, you can easily test for it).

Negative pressure should be substantial as you cool your beer from 70F to 32F or so.

I still think the best way to deal with cold crashing "suck" problem is to hook up the fermentor to a keg filled with CO2, perhaps at a bit (10% or so) higher pressure than atmospheric, and as the beer volume shrinks, the CO2 from the keg will fill the void. No oxygen exposure and no risk of breaking glass or collapsing your PET container. Just my 2 cents.

 

[55x11]

Think of the balloons as pneumatic fuses.
If something goes FUBAR at the regulator, I won't have 11 gallons of shattered glass and lost beer in my ferm fridge (and all over the floor)...

Cheers!

I agree with day_trippr, and I would never, ever use positive pressure on glass carboy unless I had some fail safe (fuse) mechanism if the pressure gets too high - like the balloon, which is awesome and very cheap way to prevent broken glass, injury and loss of delicious beer.