Cold crashing versus just kegging

[day_trippr]

The check valve breathes out, but not in.

"Everybody knows that . . ." :cross:

So, you think that plug will maintain the rather significant vacuum that will result when crash-cooling - but without risking an implosion?

Interesting...

Cheers!

 

[grathan]

Replace your airlock with one of these during the last days of active fermentation (after there's no chance of blow-off) and no O2 can enter during cold crashing.

I have observed the affects of 20# of vacuum over time. I highly doubt this works.

 

[The_Bishop]

I cover the carboy opening with sanitized foil before I cold crash for 24 hours. Gelatin fining goes in, then another 24 hours. Then I keg. Beer is very, very clear going into the keg. Carbonation happens faster because it's already cold, I don't introduce a heat load (warm keg) into my keezer, and it makes me happier that way.

 

[AnOldUR]

I have observed the affects of 20# of vacuum over time. I highly doubt this works.

I haven't used one of the silicone caps for cold crashing, but have sealed carboys other ways and never had a problem. I'm sure there are formulas, but I can't seem to find the one I'm looking for. Where are you coming up with a 20PSI change from dropping temperature 35 degrees? All I could find was a volume calculator that says the volume will go from 5 gallons to 4.96 gallons with a temperature drop from 70 to 35 degrees, so about a 5 ounce loss. Doesn't seem like enough for a 20PSI drop, but I don't know.

It does seem like if sealed glass carboys were used for many years to transport water, that a 35 degree temperature differential between filling at the source and conditions during shipping would be that unusual.

 

[day_trippr]

[...]
It does seem like if sealed glass carboys were used for many years to transport water, that a 35 degree temperature differential between filling at the source and conditions during shipping would be that unusual.

As it wouldn't make sense to transport partially filled vessels you can bet they were filled to the top.

The issue here is the head space pressure dropping, perhaps enough to collapse the vessel...

Cheers!

 

[grathan]

I haven't used one of the silicone caps for cold crashing, but have sealed carboys other ways and never had a problem. I'm sure there are formulas, but I can't seem to find the one I'm looking for. Where are you coming up with a 20PSI change from dropping temperature 35 degrees? All I could find was a volume calculator that says the volume will go from 5 gallons to 4.96 gallons with a temperature drop from 70 to 35 degrees, so about a 5 ounce loss. Doesn't seem like enough for a 20PSI drop, but I don't know.

It does seem like if sealed glass carboys were used for many years to transport water, that a 35 degree temperature differential between filling at the source and conditions during shipping would be that unusual.

20" is an estimate after watching my plastic fermeter collapse in on itself.

 

[orangehero]

20 psi vacuum ≠ 20" Hg vacuum

I doubt the carboy will implode. If my caculations are correct, then assuming you have 5 gal of beer and 1 gal of headspace at 70°F and cool the beer down to 34°F, then you should see approximately 3" Hg of vacuum (or 1.5 psi vacuum). I'm not an engineer and could be wrong though, the different measurements for vacuum are a little tricky.

 

[grathan]

This was a speidel tank with 4 gallons of headspace. About 80* to 33*. I wonder what you would calculate there?

I bet with the silicone stopper design more vacuum would be better than less anyways.

 

[AlDogWV]

So, question to all of those worrying about oxygen and CO2 blankets being nonexistent: have you ever had a serious issue with oxidation as a result of conventional cold crashing??

I leave the airlock right in the primary fermenting bucket OR glass carboy (whichever vessel happened to be handy when I first put the wort into a fermenter) and drop it down into my chest freezer for a few days. I then syphon the crashed beer into the keg.

I've done it this way at least a hundred times and have never had any hints of oxidation or off flavors.

The whole balloon get-up seems very excessive to me. Have fun with your experiments and all, but I don't have time to worry about things that really are of no worry.

 

[AnOldUR]

The issue here is the head space pressure dropping, perhaps enough to collapse the vessel...

The issue is the contracting of both liquids and gasses at cooler temperatures creating a vacuum.

Finally found out that it's the Ideal Gas Law we're dealing with and a calculator that I could figure out how to use. :cross:

I'm coming up with a 1 psi drop in pressure in about 1.5 gallons of head space with a 35 degree drop in temperature. Close to the same number as orangehero got.

Bottom line. No, you won't implode your glass carboy, and no, you won't suck the silicone stopper into the carboy. You will suck a very small percentage O2 into the head space when you remove the stopper, but absorbsion is a matter of exposure time. Just transfer right after removing the stopper and you're good.

Like I said. I've never used the silicone stopper for cold crashing, but thought it might work well if put on after removing a blow-off tube. Personally, I've simply been switching to a carboy cap with caps on both openings when I cold crash.

 

[hunter_le five]

have you ever had a serious issue with oxidation as a result of conventional cold crashing??

.....

I've done it this way at least a hundred times and have never had any hints of oxidation or off flavors.

No and ditto.

I cold crash and have never taken any measures to prevent oxygen from getting sucked into the primary. I've yet to taste anything that tastes like oxidation as a result.

Granted, I'm not doing any sort of aging and tend to finish my kegs while they're still *relatively* young. Maybe in the long-term some sort of oxidation would occur, but I have experienced no adverse effects, so I won't worry about it.

 

[grathan]

I ruined 2 of my most expensive batches a year ago due to cold crash. The head space was 4 gallons and the time was a week at 34*. That is a fairly large head space and the time spent cold crashing is a bit excessive, but undrinkable none-the-less.

 

[Gameface]

This was a speidel tank with 4 gallons of headspace. About 80* to 33*. I wonder what you would calculate there?

I bet with the silicone stopper design more vacuum would be better than less anyways.

I use speidel fermentors, the 60L ones and I typically have 10.5G of beer in them (so a good 5G worth of head space). I purchased additional pour valves that I use on the top bung to connect to my blow off tube (see pic). When I cold crash I close that valve and I've never had the fermenter collapse.

I'd like to know more about what happened with yours.

 

[orangehero]

This was a speidel tank with 4 gallons of headspace. About 80* to 33*. I wonder what you would calculate there?

I bet with the silicone stopper design more vacuum would be better than less anyways.

2.3" Hg vacuum or 1.1 psi vacuum.

I ruined 2 of my most expensive batches a year ago due to cold crash. The head space was 4 gallons and the time was a week at 34*. That is a fairly large head space and the time spent cold crashing is a bit excessive, but undrinkable none-the-less.

The headspace is not what determines how much suckback you have, rather it's mostly the volume of beer.

How long do you typically cold crash? Without finings I've never seen beer to clear to any significant degree until at least a week.

 

[brew_ny]

I ruined 2 of my most expensive batches a year ago due to cold crash. The head space was 4 gallons and the time was a week at 34*. That is a fairly large head space and the time spent cold crashing is a bit excessive, but undrinkable none-the-less.

I cold crash 11.5 gallon batches in a 13 gallon fermenter just dumping the water out of a three piece airlock, and cold crash for 48 hour after it hits 34 F

and never had a problem

but as you say 4 gallon head space and a week may be a bit much

but didn't you say before you dump 50 % of your batches?

S_M

 

[grathan]

Jeeesh I wish I took a picture. It's a different tank than yours. The top is smaller, maybe 8" across? I think its 8 gallons. I am not sure. It could be the physics of the tank design or it could also be that your valve leaked under vacuum (highly likely unless there was a massive rush when you cracked it).

The beers that were ruined were massively dry hopped beers. 8 oz+ dry hop. If you've ever done 2+oz/gal before you already know oxidation can be an issue.


I disagree with the statement about it being the volume of beer and not the headspace that creates suckback. The air condensates which causes the vacuum, sure the liquid may shrink a little, but its nothing compared to the air. When I cold crash a full carboy there is very little suckback.

 

[orangehero]

I disagree with the statement about it being the volume of beer and not the headspace that creates suckback. The air condensates which causes the vacuum, sure the liquid may shrink a little, but its nothing compared to the air. When I cold crash a full carboy there is very little suckback.

Although the air plays a part the liquid shrinkage should have a more significant effect.

For example:

If you have a 25 L vessel filled with 20 L of beer and chill from 20°C to 1°C, you will create ~2.4" Hg vacuum.

If you have a 25 L vessel filled with 5 L of beer and chill from 20°C to 1°C, you will create ~2.1" Hg vacuum.

 

[grathan]

Just as if you were to boil in your kettle with the top sealed it would explode, and equal an opposite reaction occurs when the gas is cooled. This is Charles Law.

If you were to leave a scuba diving tank in the sun. It would increase 9psi for every degree Celsius temperature increase. Much more significant than the liquid numbers.

 

[j1n]

I ferment in a chest freezer and at the end of fermentation when im going to cold crash, the chest freezer is mostly filled with co2 since its been closed most of the time and all the co2 produced from the beer is in there. So when i cold crash there is prob some o2 in there but id say 90% is co2. as soon as you stick your head in a little and sniff all you get is that sharp co2 up your nose.

 

[orangehero]

Just as if you were to boil in your kettle with the top sealed it would explode, and equal an opposite reaction occurs when the gas is cooled. This is Charles Law.

That doesn't refute my statements. You're welcome to calculate it for yourself.

If you were to leave a scuba diving tank in the sun. It would increase 9psi for every degree Celsius temperature increase. Much more significant than the liquid numbers.

Heating a closed scuba tank at atmospheric pressure 1°C will not generate 9 psi. Our carboys aren't pressurized to 3000 psi, which I'm assuming are the conditions you are referring to.

 

[AnOldUR]

If you were to leave a scuba diving tank in the sun. It would increase 9psi for every degree Celsius temperature increase. Much more significant than the liquid numbers.

So, you're going to compare a steel tank that starts at 3000psi and contains 100 moles of gas to a carboy starting at atmospheric pressure (~15psi) and less than 1 mole? :smack:


edit:
oops . . . didn't read all of orangehero's post first. Beat me to it.

 

[grathan]

That fact that it increases psi when it is already at 3000 psi should say something..

 

[grathan]

That doesn't refute my statements. You're welcome to calculate it for yourself.

I have no idea where you get your numbers from so I cannot. I either have to assume my full carboys leak when drawing so much more vacuum than the half-filled ones, or simply accept your comments as truths.

 

[AnOldUR]

That fact that it increases psi when it is already at 3000 psi should say something..

It says you have zero understanding of gas laws.

 

[grathan]

It says you have zero understanding of gas laws.

I have all night. Why not educate me?

So your also saying that liquids condense more than gas does given equal volumes and temperature drops?


*edit nevermind. I see a few posts back your guessing at psi drops and now you're an expert all the sudden.

 

[djonesax]

Replace your airlock with one of these during the last days of active fermentation (after there's no chance of blow-off) and no O2 can enter during cold crashing.

This got my wondering... If you did this during active fermentation the beer might be a little carbonated and pressure would build up. Then as it cooled the contained C02 would reabsorb into the liquid... Potentially making force carbing a little bit faster? Or am I way off?

 

[grathan]

Or it might pop out under pressure and the mold from the fridge would ruin your beer.

 

[passedpawn]

Back on topic...

I always cold crash before kegging. All I have to to is push a button a few times and my beer goes from 65 to 32. Why not?

 

[AnOldUR]

Or am I way off?

It has a flap that works like a check-valve. On exhaust, it will act the same as an airlock, letting any CO2 pressure escape. On intake, it seals and blocks outside air from coming in. That is why it should work well for cold crashing, but no pressure would build up for carbonation.

But like others have said, the vacuum formed and the amount of O2 that makes it into your carboy through the airlock from cold crashing is very small. The worry about O2 exposure is a bit of a boogeyman. If you cold crash for a couple of days the amount of absorption is minimal. You’ll probably have finished your beer well before any sign of oxidation is noticeable, if ever.




That said, I'm OCD and seal my carboy during cold crashing.

 

[cgrivois]

The more of these damn posts the more cofused I get. So now were saying that cold crashing a few days should result in too much O2 obsorbtion. What about lagering for three weeks. Or should I not lager in my fermentation bucket.