Converting Volumes of carbonation to other units

[jason.koehler]

There seems to be a black hole in the vastness of the internet when it comes to that common term brewers use for carbonation levels in beer (or soda for that matter) - volumes of carbonation. Strange enough, there isn't even a Wikipedia entry on it...

For some foreign customs reasons, I need to convert volumes of carbonation to either kilopascals (kpa), or to kilograms of square force (kgf/cm2) at 20 degrees C - if this is even possible.

My memory is that one volume of carbonation is 1 liter of co2 in 1 liter of liquid at 1 atmosphere at 20 degrees - given that it is already metric, it doesn't seem like it would be such a chore to find a calculator, but I have totally struck out after about an hour's searching.


Any ideas?

[TL Services]

Bizarre...but my only guess is that, as the units you're being asked for are pressure, then the data would be the partial pressure equivalent of whatever level of dissolved CO2 you have.

Anyway, you should be able to use standard solubility tables as a 'reverse look-up', eg. at 20 deg C:

1.0 bar (absolute) CO2 partial pressure = 0.862 v/v
1.5 bar (absolute) CO2 partial pressure = 1.293 v/v
2.0 bar (absolute) CO2 partial pressure = 1.725 v/v
2.5 bar (absolute) CO2 partial pressure = 2.156 v/v

Having just played with these numbers, they give a conversion factor of 1.159, ie. multiply the v/v figure by 1.159 to give partial pressure (in bar) at 20 deg C.

Now, since 1 bar = 100kPa, that changes the factor to 115.9, to give partial pressure on kPa.

Hope that helps!

[dick murton]

Strange indeed. My guess is that they are concerned about pressures exceeding safety limits of the kegs / bottles or whatever final package you are using, perhaps particularly in relation to the temperature or external pressure (if flying the stuff) during transport. Perhaps they are worried about the packages blowing up / leaking. But in this case, I would have thought they would have wanted guarantees about the package strength.

[jason.koehler]

Thanks TL, I think I can work with that.

Dick, since 97% of beer sold in Japan is made by Japanese big breweries, they are concerned about minor brands and imports not being recognized as 'beer' by consumers, and perhaps open the can unaware that it is under carbonation. They require minor brands to show they are carbonated when they have over 49 kilopascals of pressure. It is really just for labeling purposes.

Cheers!

[dick murton]

Thanks. I often thought Japan was slightly weird at times, but hey, isn't every country?

[TL Services]

By my reckoning that's anything above 0.4 v/v has to be labelled..!

[TGTimm]

Look at a metric system Pressure/Temperature chart for CO2. Go to the row for 20 deg. C. Follow the row until you find your carb level in V/V (a dimensionless number, doesn't matter ASE or metric). Look at the top of that column and you have your pressure.

[dpcook]

I was told by a champagne producer that the 12 grams of CO2 per liter is equal to 6 bar at 20C. 3.92 grams of CO2 per liter is roughly 2 volumes of CO2.