Carbon dioxide, also known as CO2, is a colorless, odorless, non-flammable and slightly acidic liquefied gas. It is sold commercially worldwide under pressure in steel cylinders or bottles called tanks. CO2 tanks can be used for a variety of things. Most popular uses include carbonated beverages, beer making, paintball guns, medical-grade usage, metal fabrication applications, catering, and fire extinguishing. CO2 tanks need to be hydro-tested every five years, and the test d