Tyler.W
Well-Known Member
I have started spunding at the end of fermentation to carbonate my beer. I brew 3 gallon batches, and I was using my Anvil brew bucket (4 gallon) and transferring to the serving keg (3 gallon) about 8 gravity points above expected final gravity. I am familiar with carbonation levels required to carbonate to specific volumes of CO2 at certain temperatures, and have a few apps that help with those calculations. For example, I would spund to around 28psi at 70 to mostly carbonate the beer, and then the kegerator would balance out the remaining necessary carbonation and all was well…
Then, to allow me to cold crash and remove sediment from my serving kegs I have started to ferment in 5 gallon kegs. I am following the same principals, but instead of transferring to the serving keg at 8 gravity points above target FG, I just put the spunding valve on the fermentation keg and spund there. My last beer I did that, and upon cold crashing I expected to see the keg drop from 28 to 9psi based on temperature and the volume shrinking… but it only dropped a few psi down to the low 20s. I was afraid to overcarbonate my beer, so I bled it off a bit and it seemed like things balanced out pretty well.
My main question is this: are there additional considerations I need to account for due to extra CO2 headspace in the larger keg? I am assuming the reason the psi didn’t change much was slightly due to the beer having to reabsorb some CO2, but another reason is the significantly increased pressurized CO2 in the headspace. Any input would be greatly appreciated!
Then, to allow me to cold crash and remove sediment from my serving kegs I have started to ferment in 5 gallon kegs. I am following the same principals, but instead of transferring to the serving keg at 8 gravity points above target FG, I just put the spunding valve on the fermentation keg and spund there. My last beer I did that, and upon cold crashing I expected to see the keg drop from 28 to 9psi based on temperature and the volume shrinking… but it only dropped a few psi down to the low 20s. I was afraid to overcarbonate my beer, so I bled it off a bit and it seemed like things balanced out pretty well.
My main question is this: are there additional considerations I need to account for due to extra CO2 headspace in the larger keg? I am assuming the reason the psi didn’t change much was slightly due to the beer having to reabsorb some CO2, but another reason is the significantly increased pressurized CO2 in the headspace. Any input would be greatly appreciated!
