(Two questions in one topic, but they're both involving test/measurement techniques)
Is there an inexpensive way to measure the volumes of CO2 in a particular beverage? One of the things I use my CO2 tank for is recharging sodas that have gone flat, and I'd like to bring the drinks back to their original carbonation level. I've turned up several places online citing 3.7 volumes for most sodas, but there have been a few claiming that the average is 5+! It also wouldn't hurt if I try to replicate a particular beer.
Secondly, I'm wondering how I could measure the flow resistance in my particular setup. Certainly the charts in sources like the Draft Beer Manual give good ballpark figures, but with so many variables involved there's something to be said for testing and getting the actual numbers. Whether it's beer or soda, getting the balance right is important.
Examples or ideas for DIY solutions are fine, too; I'm no engineer, but I'm plenty comfortable at the hardware store.