Carbonation Calculation

[dalpets]

Hi everyone,

I want to bulk prime today and I intend to use the carbonation calculator at http://hbd.org/cgi-bin/recipator/recipator/carbonation.html.

Could someone explain the logic of why the beer temperature at bottling is factored into the calculation. After using polycar at 5*C in the secondary it's going to take a few hours ( currently 11*C) for the temp to climb to the temperature I want to bulk prime & refrigerate at for a couple of weeks. I'm thinking of 18.5*C. It seems probably not a good idea to wait too long as it will invite infection.

My point really is, if I bulk prime now at say 11*C the priming quantity recommended will be different than if I primed for storage at 18.5*C, some hours later. I'm having trouble getting my head around that.

Could someone please enlighten me.

 

[razz]

Colder temps mean the beer will absorb more gas dalpets, so to get the same amount of CO2 volumes at different temps the amounts vary.

 

[manticle]

It's a point of contention dalpets. Every time I think I've got my head around it someone suggests it's incorrect.

As far as I'm aware, the highest point the brew reaches after primary fermentation has finished is the temp you should use.

There is a bulk priming article in the wiki section that explains why. I can't promise you it's absolutely correct but I can promise you that that's essentially what I do and most of my beers turn out carbed where I want them.

 

[jonocarroll]

After fermentation the beer will have some excessive residual CO₂ dissolved in it, which is temperature dependent. If you brewed a lager at a constant 10C then it would have a certain amount of CO₂ dissolved... more than if you had brewed at 18C. If you want an exact carbonation, you need to take this residual contribution into account.

If however, you let the beer warm up for a certain length of time after it has finished fermenting, the CO₂ will come to the equilibrium for that warmer temperature (less dissolved) and you will be mainly working from the priming carbonation rather than the residual. This shift to equilibrium is why a lot of airlocks bubble after ferment is finished.

So: use the highest temperature that the beer was held at (for a reasonable time - enough to let the CO₂ come to equilibrium) in the priming calculation. If it was sufficiently warm, then it won't make much difference. If it was cold, it will.

Hope that helps.

 

[manticle]

After fermentation the beer will have some excessive residual CO₂ dissolved in it, which is temperature dependent. If you brewed a lager at a constant 10C then it would have a certain amount of CO₂ dissolved... more than if you had brewed at 18C. If you want an exact carbonation, you need to take this residual contribution into account.

If however, you let the beer warm up for a certain length of time after it has finished fermenting, the CO₂ will come to the equilibrium for that warmer temperature (less dissolved) and you will be mainly working from the priming carbonation rather than the residual. This shift to equilibrium is why a lot of airlocks bubble after ferment is finished.

So: use the highest temperature that the beer was held at (for a reasonable time - enough to let the CO₂ come to equilibrium) in the priming calculation. If it was sufficiently warm, then it won't make much difference. If it was cold, it will.

Hope that helps.

That's how I understand it too.

 

[felten]

+1 the same as manticle, it makes the most sense imo

 

[dalpets]

It's a point of contention dalpets. Every time I think I've got my head around it someone suggests it's incorrect.

As far as I'm aware, the highest point the brew reaches after primary fermentation has finished is the temp you should use.

There is a bulk priming article in the wiki section that explains why. I can't promise you it's absolutely correct but I can promise you that that's essentially what I do and most of my beers turn out carbed where I want them.

Thanks for that. I'll look it up seeing you haven't had a downside.

 

[dalpets]

After fermentation the beer will have some excessive residual CO₂ dissolved in it, which is temperature dependent. If you brewed a lager at a constant 10C then it would have a certain amount of CO₂ dissolved... more than if you had brewed at 18C. If you want an exact carbonation, you need to take this residual contribution into account.

If however, you let the beer warm up for a certain length of time after it has finished fermenting, the CO₂ will come to the equilibrium for that warmer temperature (less dissolved) and you will be mainly working from the priming carbonation rather than the residual. This shift to equilibrium is why a lot of airlocks bubble after ferment is finished.

So: use the highest temperature that the beer was held at (for a reasonable time - enough to let the CO₂ come to equilibrium) in the priming calculation. If it was sufficiently warm, then it won't make much difference. If it was cold, it will.

Hope that helps.

Thanks! I'll need to reread that a couple of times to get my head around it.

 

[bcp]

After fermentation the beer will have some excessive residual CO₂ dissolved in it, which is temperature dependent. If you brewed a lager at a constant 10C then it would have a certain amount of CO₂ dissolved... more than if you had brewed at 18C. If you want an exact carbonation, you need to take this residual contribution into account.

If however, you let the beer warm up for a certain length of time after it has finished fermenting, the CO₂ will come to the equilibrium for that warmer temperature (less dissolved) and you will be mainly working from the priming carbonation rather than the residual. This shift to equilibrium is why a lot of airlocks bubble after ferment is finished.

So: use the highest temperature that the beer was held at (for a reasonable time - enough to let the CO₂ come to equilibrium) in the priming calculation. If it was sufficiently warm, then it won't make much difference. If it was cold, it will.

Hope that helps.

To clarify...
So if my beer was fermented at 18c, and then I crash chill it for 24 hours, I should carbonate based on 18c?
If i crash chill for about a week, I should carbonate at the temperature I chilled it to if it's still at that temp at bottling?

The latter makes me really nervous of ending up with flat beer.

 

[MaltyHops]

To clarify...
So if my beer was fermented at 18c, and then I crash chill it for 24 hours, I should
carbonate based on 18c? If i crash chill for about a week, ...

In your example, I would still carbonate based on 18c ... have a look at THIS post.
The crash chilling should put a stop to significant yeast activity to produce any
more CO2 so what the level was at 18c should also be there at near zero
temps.

[Sub-total: $4]

 

[Screwtop]

To clarify...
So if my beer was fermented at 18c, and then I crash chill it for 24 hours, I should carbonate based on 18c?
If i crash chill for about a week, I should carbonate at the temperature I chilled it to if it's still at that temp at bottling?

The latter makes me really nervous of ending up with flat beer.

This is what you will find mentioned on most priming calculators.

Upon completion of fermentation, a certain amount of CO2 remains in the beer. This amount of "residual CO2" depends upon the warmest temperature reached over a reasonable period of time during fermentation.

However:

If however, you let the beer warm up for a certain length of time after it has finished fermenting, the CO₂ will come to the equilibrium for that warmer temperature (less dissolved).

So: use the highest temperature that the beer was held at (for a reasonable time - enough to let the CO₂ come to equilibrium) in the priming calculation.

This must be taken into account if the temp increased following fermentation.

Screwy

 

[pk.sax]

Whatever the temperature was at the end of active fermentation.
Beyond that, if you chill it down, it is still the end of fermentation temp (being the warmest).
If you give it a D rest in the end by raising the temp a few degrees, it is the final hottest temp you got to.

Solubility of CO2 decreases as you raise temp so it will lose carb. However, chilling it down won't really force in more CO2 unless you have a source of that hooked up. It will be absorbing air and with priming and bottling, the yeast will use that extra absorbed air up, negating the extra dissolved O2 pressure you got by chilling. Just saying that don't consider the CC temp for carbing.

Edit: beaten by a screwy