FYI, i work in this industry. There are two main types of CO2, "Beverage Grade" and then everything else. The difference between the two is that beverage grade CO2 has less TRS, and HC, gasses in it, such as H2S, CS2 ect... Basically stinky gasses that make your soda smell like farts. Anyway, almost all CO2 that is used is beverage grade CO2. The stuff that isn't beverage grade gets turned into Dry Ice. Most plants that have CO2 as a byproduct run it through a lot of filtering processes to make it nice and clean "beverage grade". Most Welding CO2 is Beverage Grade as places that make CO2 always try to make the best stuff they can. Only if something breaks or doesn't work correctly do they have non-beverage grade CO2.