Cold Crashing airlock

[wogamon]

I was looking for a way to avoid suck-back and oxidation when cold-crashing. I heard some people use a balloon, so I built this thingy. Balloon will be filled with co2 of course. I'm kinda proud of this device so I thought I'd share.

 

[tjpfeister]

That's a clever Idea and a little more fail-safe than slowly "crashing." Wish the mobile app allowed for likes

 

[C-Rider]

I'm "cold crashing" a lager. I just took it down a few degree's every 12 hours and never had any suck back.

 

[ptarmigancraft]

Spray plastic wrap with starsan and put it over mouth of carboy... I do this with every beer and have never had any issues.

 

[FrozenOcean]

I tried that once. Basically, I put the balloon on the airlock before fermentation had completed, so that it filled up with CO2 naturally produced from the beer.

Didn't really work though... The balloon didn't inflate very much. I think the fermentation wasn't generating enough pressure, maybe got it on there too late. Not enough CO2 was captured to offset the "suck back".

So maybe filling it from a CO2 regulator would work better. Will be interested to see the results!

 

[iijakii]

Spray plastic wrap with starsan and put it over mouth of carboy... I do this with every beer and have never had any issues.

Do you slowly raise it back up? Otherwise right when you take the plastic wrap off a ton of air gets sucked in with force.

 

[Bellybuster]

Just use an "S" airlock or reduce the amount of liquid in them, easy.

 

[cooper]

What Belly said. An "S" airlock is great for that and you can put just enough starsan in it to where it'll bubble both ways. Or cold crash slowly but who the heck has time for that right??

 

[wogamon]

I'm not too concerned with the liquid, rather the o2 introduction. Anyway I'll post results. Crashing it later next week.

 

[Beerswimmer]

Great idea. I have always wondered on the amount of air that actually gets in during the cold crash. Since I know that some liquid will get sucked in I always fill my airlock with a mix of vodka and starsan when it goes into the fridge.

 

[carvetop]

I replace the airlock with a solid stopper when cold crashing. I don't remove it until I'm ready to transfer with CO2. Yes, air gets sucked in when you remove the stopper but I immediately purge and then do a closed transfer.
There had been some concerns voiced in other threads that the vacuum created could either suck the stopper in or, worse, break the carboy. Neither of these things have happened... yet.

 

[cmoewes]

What is the density difference of 5 gallons of beer between 75F and 34F?

According to this http://www.engineeringtoolbox.com/water-specific-volume-weight-d_661.html the specific volume of water at 32F and 70F are 0.01605 and 0.01602 which seems to represent a very minuscule volume change which would result in an equally small amount of air being sucked into the carboy.

I admit the math is beyond me but maybe someone could actually calculate the amount of shrinkage between 5 gallons water @75F and what it would shrink to onces cooled down to cold crash temperature range.

 

[wogamon]

I ferment in a plastic bucket primary only so the air space is considerable. I think you're right that the water density change is minimal, but if you have few litres of air then there will be... Shrinkage

 

[wogamon]

Update: It worked quite well, and shrinkage was significant. A fairly full balloon went down to empty. That being said I think some kind of "balloon clamp" would be good to add for peace of mind. I think all the seals were good but it's possible there could have been a slow leak.

Also it was difficult fitting the balloon along with the bucket into the fridge...hadn't thought of that.

My first time cold crashing and I'll definitely do it again. It was nice to have a super solid yeast/trub that didn't disturb easily during racking to keg, and the beer is nice and clean.

 

[user 204491]

Hey, I do exactly like that when cold crashing, and it works every time. I use the smallish children's punch balloons and fill them with CO2 from my tank. They shrink considerably during cold crashing, and then when I take my fermenter out to warm up on bottling day the fill back up some. I pretty much leave them attached until I'm draining into my bottling bucket, at which point I remove it and put the hose from my CO2 tank in the bung hole (after purging my bottling bucket with CO2).