‍Carbon dioxide (CO2) is a nonflammable, colorless, odorless gas. It is found in air at concentration of about 0.03%. Carbon dioxide may exist simultaneously as a solid, liquid, and gas at a temperature of -56.6˚C and a pressure of 60.4 psig. At a temperature of -79˚C and atmospheric pressure, carbon dioxide solidifies forming “dry ice” at density of 97.4 pounds per cubic foot. Because of its low concentration in the atmosphere, air is not a suitable feedstock for carbon dioxide production. Rather, CO2 is obtained from by-product streams from various manufacturing processes. Bulk quantities of carbon dioxide are usually stored and shipped as liquid under elevated pressure and refrigeration.

Blanketing and purging of tanks and reactors. It is also used as shielding gas in the arc welding process. It is the source of the bubbles in soft drinks and other carbonated beverages. It is used to fill certain types of fire extinguishers that rely on its inert properties, densities, and low temperature when released from high-pressure storage.In addition to its “inert” properties, carbon dioxide, as dry ice, is used to freeze a variety of foods.