Dissolved CO2 is dissolved CO2 for our purposes, and the controlling factors are temperature, pressure, and time. You can only affect one of these, and that is time. Agitating the liquid exposes more of the liquid to the gas, thus making the CO2 mix into solution more rapidly. Shaking the beer doesn't do anything more than help speed the process along. Don't believe anyone that tells you they don't shake because it affects the beer. The important factors are temperature and pressure. Use the standard chart to find the volumes of CO2 you want, and get going! Also, all carbonation using CO2 under pressure is force carbonation, regardless of the speed you perform it at.
http://www.homebrew.com/pdfs/CO2chart.pdf
Use the carbonation chart at the link above, or use the same chart available in many places around the web. At the bottom of this page are more links for carbonation that might help. Don't make this tougher than it is, and don't try to re-invent the wheel, just follow the process and learn the rules to be happy!
The best way of carbonating your beer is to set the pressure and leave the beer alone in the fridge for a few weeks. That solves two issues. The first is nice even carbonation, and the more important one is proper conditioning. So many people don't let the beer condition properly and are in a hurry to carbonate and drink it. Both carbonation and conditioning can happen at the same time in the fridge ot kegerator, so patience is the best method, and it is nearly foolproof. (OK, it is only fool-resistant, they make better fools every day).
I just don't see why people have a problem with carbonating by the numbers, regardless of shaking (rapid force carb) or not (regular force carb).
As for the main question "how much CO2 is in my beer?" The answer is still simple by using the chart. For a given pressure at temperature, you have given volumes of CO2, with variations not really measurable by human taste or feel. If you are carbonating your beer by a proper method where you know the temp and pressure, you already know how much CO2 is in solution. If you make a "bleed-off gauge" or whatever you might call it (NB part #K088), you can measure the pressure, but that is not really ever needed because the proper pressure is what your regulator should be set at for serving. If you are just setting your regulator to some arbitrary number and letting the beer sit until it "seems right" you deserve whatever happens.
After doing this for a long time now, I have a decent grip on rapidly force carbonating my brew. Before I do any racking, I chill the vessel/fermenter for a few days whether it be primary or secondary, to make sure the yeast drops out as much as possible, then I'm racking cold clear beer into the keg to start with and don't need to chill the beer much if any before carbonation. If you can't chill your fermenter, no worries, just get the beer in the keg cold before carbonating. Once I get the beer into the keg, I start with setting the regulator to about 30psi for the first shaking segment, connect the CO2 line to the GAS port, and then lay the keg on its side and roll back and forth for ~3 minutes. I then disconnect the gas line and continue shaking/rolling for another few minutes to let the CO2 dissolve into the beer. This shaking without the CO2 connected drops the pressure inside the keg down to where I can drop my regulator pressure for the next segment and reconnect the CO2 without getting a flow of beer back into the CO2 line when I lay the keg back over again (yes that can happen, get clear CO2 lines to be able to see, and shake disconnected for as long as you shook with the gas connected and you won't have a problem). I then stand the keg up, drop the pressure on the regulator to 20psi and connect it again, and then slowly lay the keg back over with the CO2 connection on the lower side so I can hear the bubbles of CO2 going into the keg. I shake/roll until I hear the flow of bubbles slow down significantly. This is the indicator to disconnect the gas again, and shake for a few more minutes to again let the gas go into solution before connecting the gas at the serving pressure as determined by the chart. At this point it is time to set the regulator to the "finished" or "serving" pressure, and connect the CO2 once again and roll/shake until I don't hear any more flow of CO2 into the beer. Then it goes into the kegerator and is just about perfect for serving after some settling time.
This method is nothing new, and yields very accurate and trouble-free rapid carbonation. I've never over-carbed doing this because the high-pressure segments are quite short, and you have an audible reference to let you know when the pressure is reaching equilibrium at the 20psi segment. I'll be glad to show anyone how to perform this method if you are in the
We also assume at this point that you have a balanced serving system. If you do not have a balanced system, and are doing strange things to serve your beer, that is a whole other posting to be made.You should be able to set your regulator at the same pressure as you carbed your beer for, and serve. If not, fix it. Skip the tricks and do it right, and thank us later.
If you ever meet someone who tells you to just set the regulator at some higher pressure and walk away for a few days until it seems right, kick him for the rest of us because that causes more problems and more redundant postings than anything else I've ever seen.
http://www.homebrew.com/articles/article12018101.shtml
http://sdcollins.home.mindspring.com/ForceCarbonation.html
