Help with gas

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homers brew

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Afternoon all,

How is the rate of gas absorption in a liquid calculated, or is this knowledge usually gained empirically?

What I want to do is to gas up my beer in a corny, drop it down to 0 degrees-ish and use a CPBF, but wondered how I know when the correct amount of co2 has been absorbed.

Also, is it better to carbonate at lower temps if i am going to be dropping the temp to bottle anyway?

All the best.
 
I was also thinking along the lines of caronating at high pressure (30psi plus .... I hear you scream...buckets of foam) but, with knowledge of the rates of change of gas transfer, stepping down to the correct pressure at the right time. Leaving to settle for a shorter while than originally would be required to get the steady state carbonation correct, i.e. correct vols of carbonation for taste.

Thus speeding up the carbonation process.
 
First off the important thing is to decide just how much carbonation you want in the beer. I know (from carbonating water) that 30psi applied to a corny with 15L of water in it at 18C and shaken from side to side 100 times will give me a similar level of carbonation to Coke and lemonade . . . Just a tad too much for beer. . . . Dropping down to 20 psi and repeating the 100 shakes 3 times gives me a level similar to bottled lager . . . still too much for my tastes . . . 10 psi and repeating the 100 shakes, 10 times, gives me the carbonation I like in bottles beers.

I use a carbonation chart to calculate what pressure to set to give me the level of fizz I want (*), set that and then shake 100 times several times over the period of a few hours. once I have achieved that, I turn the gas off and chill to near zero, then bottle using my Beer Gun and a very low pressure on the keg (2.5 psi).

(*) Brewers Contact has a carbonation chart on the back page this issue :whistle: . . . . I have a spreadsheet that I use to generate the the chart . . . I can pass the formulae on to whoever if someone wants to write a php calculator (EB I'm looking at you :D).

Edit: Oh Go On then the formula is
Code:
Pressure = -16.6999 - (0.0101059*T) + (0.00116512*(T*T)) + (0.173354*(T*V)) + (4.24267*V) - (0.0684226*(V*V))

Where T = Temperature (in Fahrenheit)
      V = Desired carbonation in Volumes

The Published values (US unfortunately so I think they are ~ 0.5 Vol too high) for typical levels of CO2 in beer are

Low Carbonated Ales  eg English Bitters = 1.75 Vols Of CO2
Highly Carbonated Ales eg Lagers = 2.25 Vols Of CO2
Very Highly Carbonated ales eg Wheat Beers, Belgian Ales = 2.75 Vols CO2
 
Cheers Aleman,

I assumed shaking was not ideal.

And I must declare my interest here as I'm looking into force carbonating at 5+bbl lengths, so shaking is not necessarily the easiest option. Although the 'plan' is more in the viability/ development stage at the moment and on a part time basis. I suppose this is my 'coming out' - i'm married with kids by the way, so no, not that way.

If anyone knows where some 5-10 bbl shiney (just tanks, pumps, HE, etc, not full brewery, and certainly not at some of the silly ebay prices) can be found at the right price let me know.

It's not really the steady state solution, but the gas transfer dynamics I was after, thus giving me the rate of carbonation. So to calculate if I could carbonate quicker by 1) raising/lowering the temp, 2) raising the pressure initially, 3) A mixture of the two, or 4) increasing the surface area of the beer, then this would be great. But I would need to know by how much this affects the rate of carbonation so as to not 'overshoot' the carbonation level required too much and have to wait for it to come out of solution.

However, if I recirc through a pump to agitate, mmmmm?

Do I need to change my allegiance to p-b or somesuch if I register a brewery. :)
 
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