Cold crashing in a keezer with other “finished” kegs

[Rungus]

I have a 6 keg keezer thats set to 38-40F and 12 psi (~2.4 volumes) with the tank/regulator inside. I just dropped in a keg that I want to chill down to 32F. How can I do this without messing up the carbonation of the other kegs? I don't have another fridge/freezer for cold crashing and dont really want yet another fridge. I was thinking of lowering the regulator to 8 psi for the one keg and shutting the valves to the rest but won't the other 6 kegs absorb the other 12 psi headspace and get more carbonated/the regulator gets colder and the 8 psi setting changes? This feels tricky!

 

[refect]

How long do you want to keep it at 32 F? Someone correct me if I'm wrong, but couldn't you either just shut the gas off to the other kegs (assuming you have a manifold setup), or disconnect the gas from the other kegs so they won't absorb any extra co2 other than what is in the headspace? Then, once they warm back up to 38-40 F, wouldn't that small amount of co2 that was in the headspace and got absorbed come back out of solution and equalize again at the warmer temperature?

I would think this is what would happen and would be the easiest approach, but I could be wrong.

 

[mac_1103]

Turn off the gas. Pull the PRVs on all kegs. Turn the gas back on at 8 PSI.

OTOH, what's wrong with just cold crashing at 39F?

 

[redrocker652002]

Turn off the gas. Pull the PRVs on all kegs. Turn the gas back on at 8 PSI.

OTOH, what's wrong with just cold crashing at 39F?

I have to admit, I thought the same thing.

 

[Broken Crow]

shutting the valves to the rest but won't the other 6 kegs absorb the other 12 psi headspace and get more carbonated

No. With the valve shut, a sealed properly carbonated keg is no different than a bottle or can of beer, your CO2 volume will stay the same as long as you don't serve from it. If you want to drop the temp and readjust your regulator for only the one connected keg that you're crashing, go ahead. Just don't serve from or reconnect the CO2 to the others until you've finished and brought the temp and regulator pressure back up to your original 12psi @ 38°-40°.
As said above though; What's wrong with crashing at 38°?

 

[marc1]

I have a 6 keg keezer thats set to 38-40F and 12 psi (~2.4 volumes) with the tank/regulator inside. I just dropped in a keg that I want to chill down to 32F. How can I do this without messing up the carbonation of the other kegs? I don't have another fridge/freezer for cold crashing and dont really want yet another fridge. I was thinking of lowering the regulator to 8 psi for the one keg and shutting the valves to the rest but won't the other 6 kegs absorb the other 12 psi headspace and get more carbonated/the regulator gets colder and the 8 psi setting changes? This feels tricky!

What is the reason you are hooking the cold crash keg up to CO2? What is special about 8psi vs the 12 that the rest of the keezer is on?
How about cold crashing without co2 or just using the 12psi the rest are on?
I think I'm missing something

 

[mac_1103]

What is the reason you are hooking the cold crash keg up to CO2? What is special about 8psi vs the 12 that the rest of the keezer is on?
How about cold crashing without co2 or just using the 12psi the rest are on?
I think I'm missing something

The OP's "problem" is that 12 PSI at 32F will over-carbonate his beer. Even if he doesn't hook up the new keg to the CO2, the carbonation in the other kegs will increase as the temperature decreases.

 

[marc1]

The OP's "problem" is that 12 PSI at 32F will over-carbonate his beer. Even if he doesn't hook up the new keg to the CO2, the carbonation in the other kegs will increase as the temperature decreases.

OK, I get it now, kind of. Turn the gas down to 8. Lower the temp. Or don't turn it down and keep the temp the same.

 

[mac_1103]

Why does the cold crash keg have to be on gas?

And why does it have to be at 32F? I mean, if you don't have multiple kegerators/keezers/ferm chambers/etc at different temperatures, then you have to make a compromise somewhere, right?

 

[Starkers]

I think I need some help understanding cold crashing. I cold crash in the fermenter before racking to the keg to remove flocculants from suspension. Is this the correct way or should I be racking to the keg before cold crashing?

 

[redrocker652002]

I think I need some help understanding cold crashing. I cold crash in the fermenter before racking to the keg to remove flocculants from suspension. Is this the correct way or should I be racking to the keg before cold crashing?

I will defer to the pro's, but I don't think it matters all that much either way. But I have never done it in the fermenter so I will wait and see what the others say.

 

[mac_1103]

I cold crash in the fermenter before racking to the keg to remove flocculants from suspension.

I think this is fine, and probably what most people do. As long as you're doing something to prevent air from getting sucked back into the fermenter.

edit - but I am certainly not a pro and I wouldn't suggest that anyone should defer to me

 

[day_trippr]

I always cold crash my carboys (under light CO2 pressure) before kegging. It takes any of my fridges almost two days to drop 10 gallons from D-rest to my 36°F target, and I'll keg any of my ales at that point. The occasional lagers get 4 weeks with a much slower ramp...

Cheers!

 

[doug293cz]

The OP's "problem" is that 12 PSI at 32F will over-carbonate his beer. Even if he doesn't hook up the new keg to the CO2, the carbonation in the other kegs will increase as the temperature decreases.

If the kegs are isolated from the CO2 supply, then the amount of "excess" CO2 absorbed will be minimal, and can actually be calculated* if you know the beer volume in the kegs. Then as @refect said, the excess CO2 will come out of solution when the beer warms back up, again if the kegs remain isolated from the CO2 supply. No need to mess with venting pressure on any of the kegs.

*I have a spreadsheet that does this calculation. A standard keg has an internal volume of 20.4L, and 5 gal of beer is ~19L, so a "full" keg has 1.4L of headspace. If you start with a full keg at 12 psi and 39°F (4°C) and crash to 32°F (0°C), you will only pick up an extra 0.02 volumes of carbonation. If the keg were only 1/2 full (9.5L) then then extra carbonation would be 0.15 volumes. The calculated carbonation increases are only valid if you cold crash long enough to reach equilibrium, which would take a couple of weeks (+/-). And, as mentioned previously, the excess CO2 will come out of solution when the beer is warmed back up.

Brew on

 

[mac_1103]

If the kegs are isolated from the CO2 supply

Yes, my comment assumed leaving the gas supply connected. Also, I put "problem" in quotes because it's really not that much of a problem as your spreadsheet shows. All in all, I guess disconnecting the other kegs from the CO2 supply is a pretty simple thing to do. But not changing the temperature of the keezer in the first place is even simpler. When I cold crash, I do it at 38-40F because I'm doing it in a fridge that is not dedicated to beer. So serious question: does something special happen at 32-34 that doesn't happen at 38-40?

 

[Rungus]

If the kegs are isolated from the CO2 supply, then the amount of "excess" CO2 absorbed will be minimal, and can actually be calculated* if you know the beer volume in the kegs. The as @refect said, the excess CO2 will come out of solution when the beer warms back up, again if the kegs remain isolated from the CO2 supply. No need to mess with venting pressure on any of the kegs.

*I have a spreadsheet that does this calculation. A standard keg has an internal volume of 20.4L, and 5 gal of beer is ~19L, so a "full" keg has 1.4L of headspace. If you start with a full keg at 12 psi and 39°F (4°C) and crash to 32°F (32°C), you will only pick up an extra 0.02 volumes of carbonation. If the keg were only 1/2 full (9.5L) then then extra carbonation would be 0.15 volumes. The calculated carbonation increases are only valid if you cold crash long enough to reach equilibrium, which would take a couple of weeks (+/-). And, as mentioned previously, the excess CO2 will come out of solution when the beer is warmed back up.

Brew on

Wow, these are exactly the numbers I wanted to wrap my head around, thank you so much. To those asking why 32F, I was noticing that fining with gelatin at ~40F wasn't fully clarifying my beers to my satisfaction. Well, that and I have a party this saturday so I wanted to increase the rate of yeast/particulate sedimentation to get it ready by then. Some of my kegs are close to kicking (probably ~1/5th full) so it's interesting to see that the effect varies across kegs of varying fill height, which accurately describes my keezer. I'm also pleased to see that even half full, it's just .15 volumes thats really not much at all! I posted this in other forums but you guys have by far been the most helpful and insightful as a newcomer. Cheers to all of you!

 

[refect]

Wow, these are exactly the numbers I wanted to wrap my head around, thank you so much. To those asking why 32F, I was noticing that fining with gelatin at ~40F wasn't fully clarifying my beers to my satisfaction. Well, that and I have a party this saturday so I wanted to increase the rate of yeast/particulate sedimentation to get it ready by then. Some of my kegs are close to kicking (probably ~1/5th full) so it's interesting to see that the effect varies across kegs of varying fill height, which accurately describes my keezer. I'm also pleased to see that even half full, it's just .15 volumes thats really not much at all! I posted this in other forums but you guys have by far been the most helpful and insightful as a newcomer. Cheers to all of you!

I had a feeling you were dropping it that low to maximize your fining agents. As others mentioned and my initial response, I think you'd be fine if you just shut off the gas to the other kegs. The amount of co2 absorbed would be minimal and would equalize after temperature goes back up. Just don't serve out of those kegs while the gas is shut off and the volume of co2 shouldn't change much at all.

For the other questions about cold crashing. You can do it in your FV or the keg. Both are perfectly fine. Most do it in the FV in order to drop as much of the yeast, hops, adjuncts, etc. out of suspension as possible so there is less of it making it's way to the keg. I personally rather do it in the FV, but depending on what fermenter I'm using, I may also do it in the keg.

 

[crazyjake19]

I would just cold crash to 38ºF. A few extra days at 38º would be effectively no different than cold crashing at 32º.