Fermenter "imploded"

[FelixGER]

Hi,

something really strange happened I don´t understand.
Summary: Brewed yesterday, my tapwater is 20 degress C (68 F). I cannot get the wort down to lager temps to pitch. So I purge the headroom with Co2 , sealed it and put it in der fridge to pitch today. Today I open the fridge and the fermenter kind of imploded.

Crystal clear, it´s the vacuum. BUT! I also do a sealed coldcrash in those Speidels regularly were it goes from 18 degrees C (64 F) down to 3 degrees C (37 F). Works like a charm every time! No implosion. This time, it only went from 20 degrees C (68 F) to 15 degrees C (59 F)...that´s next to nothing.

Why does it work when coldcrashing beer and not when cooling down wort?

The only idea I have: The wort was purged of almost all gases due to the prior boil and so it absorbed a lot more atmosphere in the fermenter than saturated beer. Can this be?

Best
Felix

Viele Grüße
Felix

 

[Bultje76]

When you cold crash after fermentation there is co2 in solution that will come out, compensating for the pressure drop

 

[FelixGER]

You mean the beer is force extracted (?) of CO2 although normally it would absorb more CO2 when getting colder?

Pardon my english. Just getting up to speed with 'brewing english'

 

[Picker]

When you cold crash is an airlock installed? If so that would allow air in breaking the vacuum.

 

[dpeters]

I don't think you need to purge with CO2 and seal. When I cool mine down before pitch I actually want oxygen in the beer so just before I pitch in the morning I will pump oxygen in with a stone and then pitch the yeast. I think Bultje76 is right about what may be happing. You have too good of a seal so maybe put your air lock in but don't fill it and instead soak a paper towel in some vodka and stuff it in the air lock, that is what I do when cold crashing.

 

[eric19312]

It is hard to see from the picture where you are measuring temperature. If you are measuring the air inside the fridge I can't explain what you are seeing. But if you are measuring the beer through either a thermowell or just taping the probe to the fermenter below the beer line and insulating over the probe then it is likely that your controller kept your fridge on overnight. During that period the fridge reduced the air inside the fridge to about 35-40F. The air inside the fermentor would tend to chill faster than the wort in the fermentor since it has lower density and so would of chilled quite close to the air in the fridge temperature causing the implosion.

I use that same fermentor usually 11 gallon batches. I'm also struggling with chilling last 5 degrees myself -- put the wort in fridge at 74F and only getting to 70F by bed time even though I wanted to pitch at 66F. Here is a picture of how I cold crash once fermentation is done.

 

[HopHeavy]

I am a fan of @eric19312 O2 elimination efforts with canned CO2. Planning a similar method to purge and back pressure CO2 on a bottling bucket, too!

 

[FelixGER]

What Bultje76 is absolutely correct! Just got the same answer multiple times in the German forum, too.
@Picker: CC is also sealed
@dpeters: Normally you oxygenate right after pitching not before, but who knows if a prior oxygenation has ill effects...This guy from brulosophy could make an exbeeriment
@eric19312: It works fine when cold crashing so that can´t be the reason. As Bultje76 said. The wort had almost no disolved gases in it and could not compensate for the vacuum. But I´m also using your technique when making the closed transfer to the kegs to push out the beer without air getting in. But it´s not neccessary while cold crashing.
Only thing you have to do before opening the upper valve is to seal the small hole in the valve. It will suck in air the moment you open it halfway. Not in your case, of course, because you have no negative preasure.

 

[wilserbrewer]

Gas contracts more than liquid for a given temp delta. When your fermenter is mostly full of liquid the overall shrinkage of the contents will be much less.

 

[FelixGER]

Unfortunately I´m only doing 34 l batches (2 corny Kegs, NC)
My question is fully answered now. Thanks for all the input!!

Summary:
Cold crash in sealed Speidel fermenter -> no problemo (Did it two dozen times)
Cooling wort in sealed Speidel fermenter -> Ay, ay, ay! No es bueno!

 

[eric19312]

Not in your case, of course, because you have no negative preasure.

I do my primary fermentation with the same setup just the gas line is dangled into a jar of star san. When I hook up the gas I first close the valve then hook up the gas. I turn the gas on with the valve in the off position and the CO2 flows out that small hole in the valve thereby flushing any oxygen I got in the line before turning on the gas. After that I use the valve on the regulator to turn the gas on and off, usually just give it a little puff of CO2 3-4 times over a 2 day cold crash. Learned the hard way that my tubing probably leaks just a bit with contents under pressure.

The beauty of this system as you mentioned is closed transfers. Actually I am not 100% convinced of the need for closed transfers for most beers but am 200% convinced of the advantage of using CO2 to push the beer out of the fermentor into my kegs vs hoisting 11 gallons out of the fridge to something high enough to gravity transfer. Walked funny for a week after doing it that way. I will do closed transfer on NEIPA but most other beers I will just do a sloppy CO2 flush of the keg (dangle that same line into the keg and run CO2 3-4 psi for a minute, and then I push the beer in with the opening covered but not sealed, then seal, hook up the CO2 and purge the headspace 10x.

 

[eric19312]

Unfortunately I´m only doing 34 l batches (2 corny Kegs, NC)
My question is fully answered now. Thanks for all the input!!

Summary:
Cold crash in sealed Speidel fermenter -> no problemo (Did it two dozen times)
Cooling wort in sealed Speidel fermenter -> Ay, ay, ay! No es bueno!

I will try no gas next cold crash. Makes sense.

But why are you chilling wort before pitching in a sealed fermentor? Put on an airlock or even one of those sponge bungs for marking starters and let it breath.

Also since you use same fermentor I use do you have any ideas for chilling that guy a little faster? Was thinking maybe a computer fan running full time to keep air moving in the fridge might help.

 

[FelixGER]

It really works, you have some negative presure (I learned that the hard way after I opened the fermenter "co2 valve" with the co2 attached and
some air wooooshed inside through this tiny hole in the valve which is open when the valve is halfway open) but it´s not enough to cause trouble.

I purged and sealed it because I didn´t want to have it exposed to air for 12 hours with my massive headspace, nearly 50% of the fermenter. Now I opened it, pitched, purged with CO2 (massive headspace, again) because the yeast takes 20 hours or so before starting fermentation. Maybe I´m too anal about it.

I´m brewing high gravity, meaning I make a thicker wort und then mix it with water to get more beer from my setup. Next time I will cool the dilution water (10 l) down to 3 degrees C beforehand so I can pitch right away hopefully. For Cold crashing...No idea. It takes almost 2 days to get down to 3 degrees C.