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	FORUM ON BEER, HOMEBREWING, AND RELATED ISSUES
		Digest Janitor: pbabcock at hbd.org


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Contents:
  Re: Carbonation saturation (Fred L Johnson)
  Carbonation ("A.J deLange")
  German Brewing between 1850 and 1900 (Kai Troester)


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Date: Thu, 5 Mar 2009 07:30:04 -0500
From: Fred L Johnson <FLJohnson52 at nc.rr.com>
Subject: Re: Carbonation saturation

I think Joe wants to carbonate his beer by pumping in a known VOLUME  
of CO2 into his tank and waiting for it to dissolve into the beer so  
that at equilibrium he has achieved the desired amount of CO2 in his  
beer at the storage temperature. I love this idea and would like to  
give it a shot on paper.

I hesitate to post this to the Digest, as I don't quite trust my  
reasoning and knowledge. But here goes anyway.  I just remember that  
God loves me even if I'm dead wrong.

Joe: I think you meant to say that you wanted to achieve 2.5 volumes  
(not atmospheres) of CO2 in your beer. That means for every gallon of  
beer you want to achieve 2.5 gallons of CO2 dissolved in the beer. So  
if you can measure the volume of CO2 you push into the tank, then the  
volume you need to put in will depend on the volume of beer in the  
tank and the amount of headspace in the tank. It would be a simple  
answer if the tank were completely filled with beer, but then you  
wouldn't be able to quickly push the volume of CO2 you need into the  
beer, as it takes time for the CO2 to dissolve in the beer. So you  
are stuck with pushing CO2 into the headspace and waiting for it to  
dissolve into the beer. If you can actually measure the volume of CO2  
that you push into the tank, then the total volume needed will depend  
on the volume of beer, the volume of headspace, and the temperature.

I think I know where you are going with this. You would like to put  
all the CO2 you need into the tank at the end of the day so that when  
it has equilibrated between the headspace and the beer the next  
morning, the beer will have the 2.5 volumes of CO2 dissolved in it. I  
love this idea, but as you said, you are limited to 15 psi of  
pressure, which precludes you from putting enough CO2 into the  
headspace to fully carbonate the beer, assuming most of the tank is  
filled with beer rather than headspace. I haven't done the math, but  
I think you could do this with a tank that has much more headspace.

The final pressure at equilibrium at 34 degrees F will be about 14.7  
psi using the calculator I made for you for your tank (depending on  
the volume of beer you put in the tank), so I think that means the  
volume of CO2 you would need to put in (after purging the headspace)  
is on the order of 14.7 x the volume of the headspace plus 2.5 times  
the volume of the beer. For example (not your specific tank), for a  
tank of 1000 gallons of beer and 100 gallons of headspace that would  
be (100 gal * 14.7) + (1000 gal * 2.5) = 3970 gallons (15,026 liters)  
of CO2. That much volume of CO2 confined to the head space initially  
would produce a pressure of 39.7 psi if my reasoning and math are  
correct. That pressure would gradually drop until equilibrium is  
achieved at 14.7 psi at 34 degrees F and your beer would have 2.5  
volumes of CO2 in it.

I'm sure many will correct me if I've missed something.

Fred L Johnson
Apex, North Carolina, USA



Return to table of contents


Date: Thu, 5 Mar 2009 09:01:10 -0500
From: "A.J deLange" <ajdel at cox.net>
Subject: Carbonation

I think you probably mean you want 2.5 volumes of CO2 as that's a sort  
of nominal number but it depends on the style - Irish stouts, for  
example, should be closer to 1.2 volumes and wheat beers 3 or more. If  
you really do mean atmospheres then it is a simple matter of  
subtracting 1, multiplying by 14.7 (i.e. (2.5 - 1)*14.7 = 22.05),  
setting your CO2 regulator to that value and either waiting or  
shaking. When everything equilibrates the partial pressure of CO2 in  
the beer will be 2.5 atmospheres absolute (1.5 gauge). The amount of  
CO2 dissolved under these conditions will depend on the temperature.  
The formula V=3.2694 + .076221*P - 0.042274*T gives the number of  
volumes (as released to the atmosphere at sea level on a standard day)  
dissolved as a function of the gauge pressure (in psi) and Fahrenheit  
temperature. V = 3.4821 + 0.14562*P - 0.07437*T - 6.6194e-05 *P*P -  
0.0012952*P*T + 0.00053484*T*T gives a more accurate result but given  
the accuracy of most CO2 gauges it probably isn't necessary to do the  
extra math. Of course, if you put it in a spreadsheet, the spreadsheet  
does the math, not you, and you might as well have the better result.  
These formulas represent fits to the ASBC table (from the MOAs) and  
you can, of course, also consult those (there's a copy attached to my  
cooler door). The approximations are valid from 32 to 60F and 5 to 30  
psig.

In the more usual approach the brewer would decide that he wants, e.g.  
2.5 volumes and wants to serve the beer at say 40 F. He then goes to  
the ASBC table or plugs numbers into the formula until he finds the  
pressure (about 12 psig) that gives 2.5 volumes at 40 F. To illustrate  
a little further suppose this same brewer plans to lager/condition  
this beer at 34 F. He will then want to know what pressure to set for  
2.5 volumes at the lower temperature. The tables or formula show this  
to be 9 psig so his plan would be to put it in ruh storage at 34 with  
the regulator set to 9 and then when he moves it to his serving fridge  
at 40F raise the pressure to 12.

A.J.




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Date: Thu, 05 Mar 2009 10:39:44 -0500
From: Kai Troester <kai at braukaiser.com>
Subject: German Brewing between 1850 and 1900

Last year, when browsing Google Books I came across a number of old
German books that contained a surprisingly detailed description of the
brewing process and I was fascinated reading about how they brewed
beer in the latter half of the 19th century and what they knew about
it and what they didn't. Earlier that year I also visited Germany and
took a number of pictures in two brewing museums in Bavaria.

I then realized that a commented translation of excerpts from one of
the books augmented with these pictures and various diagrams and
tables from other book would make a great article for braukaiser.com.
After working on it for a few weeks I'm finally done:

German Brewing between 1850 and 1900
* Part I: Malting and Wort Production [1]
* Part II: Fermentation and Beer [2]

Grab a beer and get ready to learn about brewing back then, get amused
by what they didn't know and how much different these beers must have
been (especially when they had cats in the malthouse).

Kai

Links (remove the line breaks in the links. HBD doesn't like lines  
longer than 80 characters):
- ------
[1]
http://braukaiser.com/wiki/index.php?
title=German_Brewing_between_1850_and_1900_:_Malting_and_Wort_Production
[2]
http://braukaiser.com/wiki/index.php?
title=German_Brewing_between_1850_and_1900:_Fermentation_and_Beer




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