Hello, everyone.
I am starting my path to kegging here the next week or so, and my buddy’s mom works for coke, and got us corny kegs for 6 bucks a piece filled with soda. We also got a 20lb C02 tank for 90 bucks filled, and when I ever take it back I get 70 bucks back. 
My question is if I want to tap the soda along with the beer what should the psi be at for the soda and the beer? I don’t have a problem Tossing the soda. But, I thought it would be really cool to have soda on tap too.
Thanks in advance.
I would set your regulator for whatever pressure you want for the beer you are dispensing, and see how that works for the soda. I’m guessing the soda will be a bit flat, but you don’t want your beer to be too fizzy.
You would have to run a couple of regulators in series and set the one on the tank to as high as needed for the pop, and the subsequent one fir the beer
The soda in the keg is already carbed. Atleast that is what the tag says.
I thought the cornies just held carbonated water and then mixed with the syrup at the fountain?
Anyway, regardless if it’s carbonated or not, you’ll have to maintain adequate pressure in the headspace or the pop will go flat eventually. Same as beer.
http://www.homebrewtalk.com/f95/volumes ... eer-75042/
3.5-4 volumes is the number I have read over time. That is around 25-30psi (depending on temp).
If you are serving both soda and beer, a dual regulator is best. You could get by with disconnecting the QD’s and upping/lowering the pressure. But what a pain.
These premix kegs are typically carbonated to 3.7/4 volumes. So just like a commercial keg that has been carbonated at the brewery to lets say 2.5 volumes means you will need to do some calculations and adjustments to match the precarbonated volume of CO2 and amount of line needed to create the proper resistance for these volumes to get steady flow of liquid and no foam.
So lets say you can hold a refrigerator at 40F and the resulting liquid(soda for this example) in the keg is at 38f. Then to dispense and match pressures you would need 25 PSI at the regulator to attain 3.77 volumes of CO2 to push and match the soda in the keg.
Now dispensing is the biggest issue. With a foot, 10 feet or 15 feet of 3/16th line you will have foam. When first setting up my premix soda years ago I used 25 feet of line and it still was not enough I found it was going to require about 40ft. I finally found the answer to perfect pours, it turned out to be epoxy mixing nozzles that create artificial resistance. In my case I found 10ft of 3/16th beer line and 2 nozzles in the out tube of the cornie resulted in perfect pours with no out gassing or foam problems.
viewtopic.php?f=3&t=106276#p938913So what you would do with a keg that is carbonated is to relieve the back pressure in the keg(and have no gas supplied to the keg of course), remove the out post, quick drop two of the epoxy inserts into the tube itself and then reattach the post and attach the gas to prevent any further loss of CO2 from the mixture. It will all come back to equilibrium within a day etc… This step if done needs to be done quickly, So get the post just open a crack so it is finger tight and then release the gas, unscrew the post, drop them in reattach the post. If you daly between releasing the gas and unscrewing the post you will be sprayed with soda because you let the tank build up pressure.
Your system will vary from mine so take all this as a YRMV post whereas you may need 2 nozzles in the dip tube and 15 ft still, Or three nozzles and 5ft etc… But for any ole regular kegorator setup 2 nozzles and 10 ft should work. But maybe start with 15-20ft and 2 nozzles and you can cut back if the pour is slow etc… instead of needing more now.
Edit* +1 as stated above you will need a dual gauge regulator. One to dispense soda at 25PSI(ish) and one to dispense beer at 10PSI(ish) all is temperature and line length related when determining pressure to use for either. I for example dispense my beer/soda at 38f so I used 25(soda) w/ line explained above and 12(beer) w/ 10ft of line.
