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Author Topic: Can carboy jiggling cancel suckback during cold crashing?  (Read 3323 times)

Offline Robert

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Re: Can carboy jiggling cancel suckback during cold crashing?
« Reply #30 on: February 09, 2019, 10:52:28 am »
But in a fixed container, your volume remains constant.  If you are talking the gas only, the density of the gas will increase, but its volume will remain at the 2 gallons of head space that you started with.

In a carboy open to the atmosphere the pressure remains constant. As the CO2 gas in the headspace cools it shrinks, and air is drawn in to keep the headspace volume filled at atmospheric pressure. The volume of air drawn in is equal to the volume shrinkage of the CO2 at constant pressure, about 500 ml.
It has occurred to me before that there may be another mechanism at work:  increased solubility of CO2 in beer as the temperature drops.  As temperature drips and CO2 goes into solution, this further reduces the volume of CO2 entering the headspace, accelerating reduction  of pressure and drawing more air in.  Richard, maybe your jiggling idea could neatly offset this.
Rob Stein
Akron, Ohio

I'd rather have questions I can't answer than answers I can't question.

Offline Richard

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Re: Can carboy jiggling cancel suckback during cold crashing?
« Reply #31 on: February 09, 2019, 06:00:01 pm »
I agree that the increased solubility of CO2 will add to the suckback effect, but I have no idea how to calculate that.

In terms of when to attach a balloon, fermentation of 20 liters of 1.060 beer with 75% attenuation produces about 450 liters of CO2, so collecting 0.5 - 1 liter would mean just catching a tiny percentage at the very tail end of fermentation.
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Offline Robert

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Re: Can carboy jiggling cancel suckback during cold crashing?
« Reply #32 on: February 09, 2019, 06:21:41 pm »
I think the calculating has got you as far as it will go.  You'll have to develop this technique by good old trial and error.   But I bet it will be a workable system.
Rob Stein
Akron, Ohio

I'd rather have questions I can't answer than answers I can't question.