We are currently carbonating sodas to a CO2 volume of close to 4 in grundy tanks that are rated to 30 psi....and soon we plan to be working with much larger tanks (40 barrel) which are only rated for 15 psi. My question is whether we can achieve our high carbonation level by going to 15 psi in the tank, and then bumping in up the rest of the way with an in-line system. Any input is greatly appreciated!!
The key to dissolving CO2 is to keep the liquid cold. Have a look at the Meheen Manufacturing web site (www.Meheen-manufacturing.com I think). They have a temperature / CO2 solubility chart there. Personally I would go for in line carbonation, but your receiving tank will have to be capable of holding this amount of CO2 in solution. Decide yourself from the charts what you need, allowing say 5 psi on top of the minimum required. And of course make sure the soda stays cold.
btw - are you sure you mean 4 volumes ? - it strikes me as incredibly high. I would have thought you would have difficulty serving this in a glass.
Not sure of you set up, but normally use a mixing tank for your extract and then through a small high pressure tank which adds the water and CO2 before bottling. This is by far, I found, the easiest way for soft drink production on larger scales.