Wouter
Well-Known Member
If the capacity to absorb gasses increases why do you think it will not just take up some of the gasses in the FV.
If the capacity to absorb gasses increases why do you think it will not just take up some of the gasses in the FV.
A typical headspace above the beer in a 25 litre FV is about 3 litres. If its all CO2 thats about 6g. Only a small amount of this will dissolve, since although the top layers of beer get re-saturated with CO2 as the temperature falls, this creates a barrier to further CO2 disssolving. That said if you kept the beer at low temperature for weeks more CO2 would get dissolved since other factors come into play. And assuming the FV is completely leakproof, as more CO2 dissolves a vacuum will be pulled on the FV. I have certainly never noticed that happening. Finally 6g CO2 is equivalent to about 12g priming sugar which in the overall scheme of things ain't very muchI have no idea but hope some one else can let us know.
Thanks Terry, that is very helpful. Feeling more confident with priming volume levels now.A typical headspace above the beer in a 25 litre FV is about 3 litres. If its all CO2 thats about 6g. Only a small amount of this will dissolve, since although the top layers of beer get re-saturated with CO2 as the temperature falls, this creates a barrier to further CO2 disssolving. That said if you kept the beer at low temperature for weeks more CO2 would get dissolved since other factors come into play. And assuming the FV is completely leakproof, as more CO2 dissolves a vacuum will be pulled on the FV. I have certainly never noticed that happening. Finally 6g CO2 is equivalent to about 12g priming sugar which in the overall scheme of things ain't very much
Temperature of Beer used for computing dissolved CO2:
The beer you are about to package already contains some CO2 since it is a naturally occurring byproduct of fermentation. The amount is temperature dependent. The temperature to enter is usually the fermentation temperature of the beer, but might also be the current temperature of the beer. If the fermentation temperature and the current beer temperature are the same life is simple.
However, if the beer was cold crashed, or put through a diacetyl rest, or the temperature changed for some other reason... you will need to use your judgment to decide which temperature is most representative. During cold crashing, some of the CO2 in the head space will go back into the beer. If you cold crashed for a very long time this may represent a significant increase in dissolved CO2. There is a lot of online debate about this and the internet is thin on concrete answers backed by research. We are open to improving the calculator so please let us know of any sources that clarify this point.
The equation this calculator uses to compute the amount of dissolved CO2:
CO2 In Beer = 3.0378 - (0.050062 * temp) + (0.00026555 * temp^2)
Carbon dioxide (CO2) is a gas produced as a byproduct of fermentation. Although we generally add more CO2 for drinking our beer via priming sugar or by force carbonating, there is CO2 present in the fermenter after fermentation. Temperature is important in this, as liquids "hold" more CO2 when cooler, and release more when the liquid is warmer. The equilibrium in the fermenter under airlock therefore is pressure and temperature dependent. Warming the beer in the fermenter will then make the airlock bubble, as a sign of CO2 being released.
Relevant extract below...To quote the info on the Brewer's Friend priming calculator: https://www.brewersfriend.com/beer-priming-calculator/
A typical headspace above the beer in a 25 litre FV is about 3 litres. If its all CO2 thats about 6g. Only a small amount of this will dissolve, since although the top layers of beer get re-saturated with CO2 as the temperature falls, this creates a barrier to further CO2 disssolving. That said if you kept the beer at low temperature for weeks more CO2 would get dissolved since other factors come into play. And assuming the FV is completely leakproof, as more CO2 dissolves a vacuum will be pulled on the FV. I have certainly never noticed that happening. Finally 6g CO2 is equivalent to about 12g priming sugar which in the overall scheme of things ain't very much
Further discussion about what happens to a few grams of CO2 in the headspace isn't worth the bother in my view. You have made you views clear as have I, so let's just chill and agree to differ.Honestly, I really don't know. From this post I take that you completely seal of the vessel when you cold crash? No air lock on it?
I have no idea how long it would take for any gas to diffuse into the young beer to saturate it completely. My field is chemistry and I am not well versed into such dynamics.
But I do think this is a little too complex to just assume these things. You might not care for your process, but you can't be completely sure that what you say is true without an explanation with a basis in either experimental data or just Flux physics.
For instance, why do you think that CO2 diffuses so slow through beer that only the top layers are saturated? I am completely unsure about these rates. I spend the last half hour trying to browse some articles about this, and I am still unsure.
Further discussion about what happens to a few grams of CO2 in the headspace isn't worth the bother in my view. You have made you views clear as have I, so let's just chill and agree to differ.
Seem that it's a bit of both if these numbers are correct. I always end up with a bit of Starsan in the beer during the chill to cold crash. It doesn't bother me at all and works out far less than gets left as residue in the Starsan-rinsed bottles when bottling. Foam everywhere on bottling day for me.I just remembered my sisters husband saying once when he cold crashed a brew to 1c it got a load of starsan in the beer sucked up through the blow off tube, would this have been because the beer absorbed the CO2 or just from it contracting at the lower temp?
Hi!
My mother often says, "You want to know the far end of a fart."
I think that's what we are doing here - academic but pointless to most homebrewers.
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