Cold crashing @#$% up.

[Celiacbrew]

So I made a mistake today and didn't swap out my blow off tube when I cold crashed my carboy. It sucked up the overflow sludge and I assume some fruit flies too. I don't remember what was at the bottom of my overflow bucket but it was probably old oxyclean or something. My brain can't understand how it cleaned out the overflow bucket and five feet of tubing when it dropped 12degrees Celsius.

I think I should probably dump the batch rather than tie up bottles waiting to see if I have dark malt vinegar on my hands. Has anyone else done this and had it come out okay? Any advice on what I should have done instead of leaving my blow off tube on?

[mcgster]

Wow i never would have thought water would contract that much when it cooled. How big was the tubing (diameter)

Unfortunately not dumbing it would be a pretty big gamble! I'm surprised i haven't done this before actually i never would have thought it would be an issue!

[chalmers]

Crap.

Sorry, I haven't run into that previously. Just blind luck, not anything positive I can pin it on!

[Celiacbrew]

I've been racking my brain to try to figure it out and the best I can figure is the contraction of the liquid is what gave it enough pull to suck everything out of the blow off vessel. Oh well lesson learned.

Time to start googling how to keep oxygen out of the carboy during lagering. Maybe a solid bung and a slower dropping of the temperature.

[RubberToe]

For cold crashing I remove my bung and blowoff tube, replace with tin foil. I've heard of people using an S type air lock too, which flows both ways.

I've sucked up blow off liquid before too. Mine's usually a mason jar or gallon jug, mostly covered, containing starsan. Sometimes I dilute the starsan a bit since it foams. Starsan going into your brew isn't such a big deal and I've never had a problem occur because of it. It still sucks though.

It's wierd yours sucked so much back too.

[Celiacbrew]

I think I might have an idea of how it happened. I ramped the temperature of the carboy up to 22 once the krausen dropped and gave it a shake to help knock some CO2 out of solution (I don't know of it is true, but I think that would help the yeast clean the beer up faster). I stepped the temperature back down to do the crash but from a pressure stand point it would be the same as if I dropped it from 22 down to 3.

I also think I have an idea of how to keep O2 out. If I take the hose out of the blowoff vessel after the primary stage of fermentatjon and attach a ballon/garbage bag to it, the ballon/garbage bag will fill with CO2 during the clean up phase and then when the crash happens it will suck That co2 back in.

[CartoonCod]

I'm pretty sure it's the gas in your headspace of the fermentor that reduces it's volume when it gets colder. The liquid will a bit but probably not that much. If you reduced the headspace, (ie transfer to a Carboy before cold crashing) it should help.

[Celiacbrew]

I'm pretty sure it's the gas in your headspace of the fermentor that reduces it's volume when it gets colder. The liquid will a bit but probably not that much. If you reduced the headspace, (ie transfer to a Carboy before cold crashing) it should help.

It was in a carboy filled up to the shoulder

but this experience is okay, I can brew another batch this weekend to replace the one I lost.

[CartoonCod]

Interesting, never would have thought.

[Jimmy]

I had this happen with a 2L pitcher of starsan, sucked up 80-90% of the starsan.

[mcgster]

I had to do some digging to find the formula to calculate the change in the volume of a liquid with temperature and since there was no volumetric expansion coefficient listed for beer i used water!

So..

if you had 20L of water drop from 22C to 12C you would see a change in volume of ~53ml.

The gas is definitely a much larger contributor (and much easier to calculate the change with Charles Law). 1 litre of air dropping from 22 to 12 would decrease in volume by almost 50% or around 500ml.

Both of these results are pretty surprising to me... i wouldn't have thought either would be quite so large

[Celiacbrew]

I had to do some digging to find the formula to calculate the change in the volume of a liquid with temperature and since there was no volumetric expansion coefficient listed for beer i used water!

So..

if you had 20L of water drop from 22C to 12C you would see a change in volume of ~53ml.

The gas is definitely a much larger contributor (and much easier to calculate the change with Charles Law). 1 litre of air dropping from 22 to 12 would decrease in volume by almost 50% or around 500ml.

Both of these results are pretty surprising to me... i wouldn't have thought either would be quite so large

From how much was sucked up, your numbers don't surprise me. Would the increase in dissolved gases add to this as well?

[mcgster]

Thats a good question!

The CO2 would dissolve to form carbonic acid / bicarbonate which would probably change the coefficient of expansion but i can't seem to find out what it is!

However the alcohol in the beer would increase the contraction! The coefficient of expansion for alcohol is 5 times larger than it is for water. So assuming you had 5% alcohol beer that would mean an extra 13 ml of contraction!

[Celiacbrew]

Thats a good question!

The CO2 would dissolve to form carbonic acid / bicarbonate which would probably change the coefficient of expansion but i can't seem to find out what it is!

However the alcohol in the beer would increase the contraction! The coefficient of expansion for alcohol is 5 times larger than it is for water. So assuming you had 5% alcohol beer that would mean an extra 13 ml of contraction!

Oh sorry I should have been more clear with my question. I was meaning for the CO2 in the headspace dissolving into the beer changing the pressure in the headspace and increasing the vacuum that pulled the liquid back up the blowoff tube.

But now that you say that about the beer and the alcohol changing the expansion of the liquid, I wish that had been the question I asked. Holy crap that a huge change for such a small amount of alcohol.

[mcgster]

Interesting angle!

I'm not sure of the answer but air has a very low percentage of CO2 (something like 0.04%) and post fermentation beer is overly saturated with CO2. As the air in the headspace cooled some of the CO2 would likely dissolve in the water but since it makes up such a small portion of the air i'm not sure it would be noticeable. Now i want to do some tests...

[CorneliusAlphonse]

but the headspace is largely co2 though, not air (assuming a bit of fermentation had occured in that vessel post-sealing)

[Celiacbrew]

I can't wait to see the results of your experiment. Gases and pressure are an interesting subject.

[mcgster]

but the headspace is largely co2 though, not air (assuming a bit of fermentation had occurred in that vessel post-sealing)

Assuming that the system was air tight and he never opened it to take a sample or anything then it would be largely CO2, but he did say that there was very little headspace. CO2 is denser then air so conceivably if it was opened up a blanket of co2 would remain but air movement would likely disperse it and negate the density difference.

[GuingesRock]

Where's the gas doctor (GasMD30) when he's needed. The solubility of CO2 in beer is much greater as the beer cools. Maybe the head space was all CO2 and most of it dissolved into the beer as it became cooler. Air on the other hand, which is mostly N2, is very much less soluble. Nitrogen takes very high pressures and very low temperatures to dissolve in beer.

[mcgster]

If the airspace was completely co2 it would dissolve in the gas until the partial pressure equilibrates as the temperature goes down less pressure is required to dissolve a given amount of co2 in water however as the temperature decreases so does the pressure! I'm not sure which one would win out in this matter but given that the contraction of gas due to the decrease in temperature is so significant its likely that its the major factor! When you look at the numbers on how much volume the contraction of gas alone it could easily account for this!

Once i empty out my fermenters i'm going to try so i can see first hand though.. i'm curious