Say I have a keg of beer at around room temp. (23C/73.4F). I want 2.2 volumes of CO2 carbonation so using this calculator I figure out I need to add 25.83PSI of pressure - some time later the beer is carbonated.

To serve the beer, I decant 5 litres at a time into a mini-keg which I keep in the fridge (3C/37.4F). The same calculator says that starting from scratch, I would only need to add 7.82PSI @ 3C. But the beer is already at the correct volume of CO2, just not the right temp.

Is it as straightforward as transfer & pressurise/spund to 7.82PSI and the beer in the mini-keg will still be at 2.2 volumes of CO2? Or does the temp. difference between the kegs make a difference?

1 Answer 1


wow 25.83 PSI, that is tight.

The real world does not work like that, nor can you measure 100th of a PSI. every beverage beer, larger, ale and bitter and the differences between each home brewed batch, temperature, the length of you gas lines, beer lines and even the mood that your in can all make something taste different and perceived carbonation.

The real answer is try it and taste it and remember what you did if it was good!, is it too 'fizzy', berp the keg and turn it down / not enough carbonation, increase the pressure by 10 PSI shake the keg and try again.

I pump some of my beers to 15 psi and some to 30psi to carbonate (room temp) then in the same keg berp them to about 10 PSI and refrigerate/serve at this pressure.

As you can see from the picture, I have to serve my Russian Imperial Stout at 20 PSI just to get it out of the keg, and the Cider next to it serves between 5 to 10 PSI, I'm having foaming issues... oh the joy.

At the end of the day you need to find what works for you, your setup and your beverage, if you get too much foam when serving, then turn the serving pressure down! if it does not come out quick enough, then turn it up! simples...

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