Amount Of Bulk Priming Sugar For A Regular 23l Run

[Screwtop]

yeah i do know a little bit about this as im actually trained as a hydraulics and pneumatics tech.

Good, will be interested to hear your take on this.

We ferment some beer maybe with a closed fermenter and airlock, or maybe not. The fermentation temp has been 10C, we can calculate from a table the Co2 in solution at that temp. Then we reduce temp to 1C for cc'ing. The volume of the liquid reduces slightly, if the fermenter was left open during fermentation, or if the beer is racked to another vessel prior to cc'ing there will be no pressure in the vessel. If the temp is dropped in a closed fermenter with some head pressure (depending upon the ability of the seals and airlock fitted to the fermenting vessel). Allowing for a slight reduction in volume due to the lower temperature, where does the increase in pressure come from to increase Co2 in solution in the beer at the lower temperature??

Screwy

 

[manticle]

My last question is - if I leave my finished brew in secondary for a week before cold conditioning, will the co2 blanket remain or not (normal plastic fermenter with glad wrap, glad wrap and lid or lid and airlock - I use all three depending on whatever is at hand).

Cheers

 

[barls]

ok vessel contracts in relation to the drop in temp so the volume wont decrease a great deal but will stay in ratio to the vessel. the head pressure stays the same as its regulated by the airlock.
so we have a decrease in vessel size which could contribute to the increase in pressure then you also have the fact that beer has a high percentage of water and water being one of the few liquids that expands when it approaches freezing and boiling.
both of these factors can lead to a minor increase in pressure but its mainly the fact that as the liquid lowers in temp the solubility of co2 increases therefore needing less pressure to defuse into the liquid.
wow i almost need a beer after that.
does this make sense.

 

[Florian]

but you can see why i say its the current temp rather than the highest reached.
say you have two beers. both reach say 22 in fermenting. at this point they have the same level of dissolved co2 you then rack both in to two separate but the same size secondry/ lagering vessel. the co2 is reduced at this point but still close.
you take one and put it at 2 degrees and the other at room temp.
you leave them for 3 weeks the one thats been in the fridge will have a higher dissolved co2 level than the one that hasnt.
this needs to be taken in to account as with some styles it could mean the difference between hitting the right carb and completely overshooting it.

This is exactly how I see it as well, the one in the fridge has more C02 as it hasn't lost the C02 due to a temperature rise like the other one. But the question now is: What happens if you suddenly put the beer which has been outside in the fridge? If I understood you correctly, you say that it absorbs C02 and has eventually the same amount than the beer that has been in the fridge the whole time. Whereas I say, once it's lost it's lost and will not get back in to the beer just by itself (without pressure applied) just by lowering the temperature.

Just reading your example again, just to clarify: In your example are you transferring 3/4 through fermentation, just after the gross of C02 production has stopped, or after a few days, so there has been plenty of time for the C02 to escape at 22 degrees as no more is produced in the beer? second option would negate my statement completely.

Anyway, just thinking this would be much easier to discuss this verbally...

Manticle, I don't believe that the C02 layer disappears just by itself. In my understanding it would stay indefinately, if it does not get blown away or 'manually removed' otherwise. As it is heavier than air, it will just sit in a bucket until someone pushes the bucket over or fills water to the brim and it therefore can flow out of the bucket.

 

[manticle]

The reason I say that is because upon buying some glass demijohns for sour beers I was told that the co2 blanket would disappear completely after about 3 weeks (following ferment) and therefore I should reduce headspace in ageing vessels to 0. It certainly wouldn't hang around forever - it may be heavier than air but it pops out of the airlock ok, squeezes out past the glad wrap and certainly makes its way out of a beer glass and bottle if given the opportunity.

 

[Hatchy]

I bulk prime everything with 140g of dex (give or take a couple of grams), I didn't know there was so much involved. I've never had bottle bombs or flat beer with 140g.

 

[Screwtop]

ok vessel contracts in relation to the drop in temp so the volume wont decrease a great deal but will stay in ratio to the vessel. the head pressure stays the same as its regulated by the airlock.
so we have a decrease in vessel size which could contribute to the increase in pressure then you also have the fact that beer has a high percentage of water and water being one of the few liquids that expands when it approaches freezing and boiling.
both of these factors can lead to a minor increase in pressure but its mainly the fact that as the liquid lowers in temp the solubility of co2 increases therefore needing less pressure to defuse into the liquid.
wow i almost need a beer after that.
does this make sense.

No............. Because fermenting vessels can be plastic, metal or glass, and will not contract or expand at the same rate, or anywhere the same rate as the gas/liquid inside. Also from memory the solubility of Co2 in water is around 1.75 times "volume for volume" at 0 deg at one atmosphere of pressure and 1 atmosphere is equal to about 100 Kilopascals. I don't believe that we would ever have a situation where there was either enough pressure or a volume of 1:1 in the headspace of our fermentation vessels to achieve a significant variation in volumes of Co2 other than what existed prior to chilling of the wort. As we know, reducing temperature will not drive Co2 out of solution, therfore it should remain at the same level, but does not, the soluability increases, but only due to less volume of liquid at the lower temperature unless there is an increase in pressure at the gas/liquid interface. Unless driven off by agitation, a decrease in pressure or an increase in temperature soluability should remain stable.

So soluability will change with a drop in the temperature of the beer but without a significant increase in pressure the amount of soluable Co2 in the beer will remain the same. Heating of the beer will be required to above the point where soluability will be affected and Co2 is driven out of solution again.

My 2c

Screwy

 

[Yeastie Beastie]

I have been using THIS CHART for a while now with no dramas at all.