Carbon DIoxide, CO2, or Super-Gas?

Weldstar Specialty Gases is a trusted supplier of carbon dioxide to Northern Illinois and surrounding areas.

Most people outside the industrial gas industry recognize carbon dioxide, CO2, as the bubbles in soda and as the chemical in fire extinguishers. But CO2 is utilized in so many different forms that it is actually one of the most versatile gases available

Brief History

CO2 was discovered in the early 1600’s as the off gas of burning wood by Jan Baptista von Helmont, a scientist in Finland. In the mid 1700’s a chemist in England, Joseph Priestly, discovered sparkling water through the process of combining water and CO2 dissipated from a fermentation process which changed the taste of water and initiated the start of the soft drink industry.

One of the characteristics of the gas that was unconvered was it’s simple liquefaction process. This led to CO2 being the first commercial industrial gas to be sold as a packaged gas. As more knowledge about CO2 was discovered the only gas offered and utlizied 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. Other characteristics make it unique as well .

The best example is when CO2 creates carbonic acid after coming into contact with water. Although it is not a very powerful acid, it is an acid nonetheless and can be used to adjust the pH in certain applications where the pH is an important system parameter. This is evident in different 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. The outcome of this is that any application using liquid CO2 should be under pressure. Employees in the oil industry are aware can compensate for water in enhanced oil recovery (EOR) where the liquid is put in a blend with sand or sand like substance (proppant) and sent down an oil well to recover oil that has been trapped between layers of rock. EOR is a wide-ranging term that can refer to several different processes but the most common is fracking. Here the proppant is forced into the oil rich rock through man made fissures. As a result, the rock fractures and the trapped oil is released. When using CO2 as an alternative to water, its natural expansion of volume from liquid to gas helps enlarge the fissure and recover an additional amount of oil.

It is not commonly known that liquid CO2 is also used to dry clean clothing. In a special high pressure washer, liquid CO2 is combined with a stain remover. The laundry is then cleaned in a normal fashion using turbulence to clean the wash. When the cycle is completed, the dirt, grime and stain remover are separated from the liquid CO2. The liquid CO2 is then extracted to be used again 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 properties and is achieved through proper adjustment of temperature and pressure; this is known as the supercritical state. The supercritical state of CO2 can be generated in a uniquely designed processor. Because it is an excellent solvent, CO2 in its fluid phase is used to extract fragrances and color from flowers and plants. This process requires specific equipment and is carried out under high pressure.


Solid CO2 or dry ice is utilized applied in many different ways as a coolant. When liquid CO2 is transported through a high pressure line and released using special nozzles, it instantly transforms into CO2 snow and is used in the refrigeration or freezing of food. Dry ice pellets can be used in plae of regular ice in bins that hold perishables on long trips via roadways.

Very small cuts of dry ice are (about the size of a grain of rice) utilized as an abrasive to eliminate coating on surfaces without harming the surface itself by blasting the rice size pellets through a blasting lance. This is popular in the aircraft industry where an airplane’s body has to maintain its integrity and cannot tolerate any damage that would occur with sand blasting. This is also advantageous because is that there is no need to separate the removed coating 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 without a doubt the most versatile gas available in the industrial gas market.

To learn more about how you can be supplied with carbon dioxide in Northern Illinois for any of your specialty gas operations, call Weldstar Specialty Gases at 708-627-1007 or at

John Segura, PE

About the Author

John Segura is a licensed Professional Engineer and an experienced executive in the industrial gas world. He has over 30 years of experience covering sales, marketing and operations both domestic and international. Segura has been a leader to several teams of technicians and engineers through his work as an R&D manager for dominant gas companies. His work directed him to lead the marketing efforts of technology worldwide industrial gas suppliers. He now consults to the industry on the business specializing in operations, applications and marketing.