Carbon DIoxide, CO2, or Super-Gas?

A-OX Welding Supply is a trusted supplier of carbon dioxide to Sioux Falls and surrounding areas.

The majority of people not affiliated with the industrial gas industry are familiar with carbon dioxide, CO2, as the bubbles in certain beverages and as the chemical in fire extinguishers. CO2 is used in more forms than any other gas in the industrial gas market making it one of the most versatile products sold

Brief History

At the start of the 1600’s, CO2 was discovered as the product of wood burning by a Finnish scientist named Jan Baptista von Helmont. In the mid 1700’s a chemist in England, Joseph Priestly, discovered that the combination of water and CO2 being dispensed from a fermentation process generated sparkling water which altered the water’s taste and was the driving force behind the start of the soft drink industry.

One of the attributes of the gas that was unconvered was how easily it could be liquefied. This resulted in it becoming the first commercial industrial gas to be offered as a packaged gas. Eventually, after learning more about the gas, CO2 became the only gas offered and used in all three of its phases – gas, liquid and solid.


For those involved in the gas industry, CO2 is most commonly associated with the food and beverage industry for its use as a refrigerant or as a shielding gas in welding. CO2 also has other attributes that contribute to its uniqueness .

The prime example is when after making contact with water, CO2 forms carbonic acid. Although it is a weak acid, it is an acid nonetheless and can be used to regulate the pH in certain applications where the pH is a relevant system parameter. This is the case in some industries such as paper production, textiles, and water treatment processes. An additional benefit is that carbonic acid is not stored as an acid (such as sulfuric or hydrochloric acids). As mentioned, the CO2 needs water to create the acid so it remains CO2 until needed and is not considered hazardous like other acids.


CO2 is stored as a liquid regardless of the container. The pressure in an uninsulated CO2 cylinder is usually around 800 psig depending on the atmospheric temperature. This means that any process using liquid CO2 should be under pressure. Employees in the oil industry are aware that CO2 takes the place of water in enhanced oil recovery (EOR) where the liquid is mixed with sand or sand like substance (proppant) and pumped down an oil well to recover oil that has been trapped between layers of rock. EOR is a general term that can apply to a variety of procedures but the most frequent is fracking. In fracking man made fissures are used to pump the propant into rocks that are rich in oil. This leads to the fracture of the rock and the subsequent release of the oil inside of it. When CO2 is used instead of water, its natural expansion of volume from liquid to gas makes the fissure larger and helps recover additional oil.

Many people are not aware that liquid CO2 is also used to dry clean clothing. In a certain high pressure washer, liquid CO2 is mixed with a stain remover. The laundry is then cleaned in a normal fashion using turbulence to clean the wash. When the cycle is finished, the dirt, grime and stain remover are separated from the liquid CO2. The liquid CO2 is then removed for reuse and the clean clothes are removed and has remained dry since there was no water utilized in the process.

Every chemical (element or compound) has a state in which the three phases (gas, liquid and solid) have the same qualities and is reached through modification of temperature and pressure; this is referred to as the supercritical state. The supercritical state of CO2 can be generated in a uniquely designed processor. The fluid phase of supercritical CO2 is an exceptional solvent and is used to extract fragrances and color from flowers and plants. The process is, of course, performed under high pressure and requires highly specialized equipment.


Solid CO2 or dry ice is used as a coolant in several ways and forms. When liquid CO2 is transported through a high pressure line and passed through special nozzles, it instantly becomes CO2 snow and is applied in food refrigeration and freezing. Dry ice pellets can be used in plae of regular ice in cases that hold perishables for long over-the-road transport.

Very small cuts of dry ice are (about the size of a grain of rice) utilized as an abrasive to rid surfaces of coatings without harming the surface itself by blasting the rice size pellets through a blasting lance. This is prominent in the aircraft industry where the airplane’s bodies need to remain unharmed and not be damaged from sand blasting. Another advantage is that the removed coating does not have to be separated from the abrasive as the pellets sublimate to CO2 gas leading to a cleanup that is quite easy.

Calling CO2 a super-gas may be controversial, but it is certainly the most versatile gas available in the industrial gas market.

For more information on how you can get carbon dioxide in Sioux Falls for any of your specialty gas operations, call A-OX Welding Supply at 605-336-1125 or at

John Segura, PE

About the Author

John Segura is a licensed Professional Engineer and a well-rounded executive in the industrial gas world. He has been in the industry for over 30 years and is experienced in marketing, sales, and operations at both domestic and international levels. Segura has well-rounded experience leading teams of engineers and technicians from his years as an R&D manager for large gas companies. His work caused his eventual leadership of the marketing efforts of technology worldwide industrial gas suppliers. He still remains in the industry but now as a consultant on the business specializing in operations, applications and marketing.