Carbon DIoxide, CO2, or Super-Gas?

American Welding & Gas, Inc. is a trusted supplier of carbon dioxide to Indianapolis and surrounding areas.

The majority of people outside the industrial gas industry know carbon dioxide, CO2, as the gas used to carbonate 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

In the early 1600’s, Jan Baptista von Helmont, a Finnish scientist, discovered CO2 as the gas that resulted from burning wood. In the mid 1700’s a chemist in England, Joseph Priestly, found that mixing water and CO2 being expended from a fermentation process created sparkling water which changed the taste of water and initiated the start of the soft drink industry.

One of the properties of the gas that was unconvered was its ability to be easily liquefied. The result was that CO2 became the first commercial industrial gas to be supplied as a packaged gas. Eventually, after learning more about the gas, CO2 became the only gas sold and employed in all three of its phases – gas, liquid and solid.


For those involved in the gas industry, CO2 is most commonly associated as a refrigerant in the food and beverage industry and as a shielding gas in welding. There are also additional unique properties of CO2 that contribute to its versatility .

The prime 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 has the ability to adjust the pH in some cases where the pH is a relevant 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 requires 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 approximately around 800 psig depending on the surrounding temperature. This means that any process using liquid CO2 should be under pressure. Workers in the oil industry are aware that CO2 takes the place of water in enhanced oil recovery (EOR) where the liquid is combined with sand or sand like substance (proppant) and pumped down an oil well to recover oil that is stuck between rock layers. EOR is a blanket term to describe different applications but the most common is fracking. In fracking 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 used in place of water, CO2’s natural expansion of volume from liquid to gas increases the size of the fissure and leads to the recovery of more oil.

It is not commonly known that liquid CO2 is also applied in dry cleaning. In a special high pressure washer, liquid CO2 is combined with a stain remover. The clothes are then washed regularly applying 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 to be recycled 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 attained adjusting the pressure and temperature; this is called the supercritical state. The supercritical state of CO2 can be produced in a specially designed processor. The fluid phase of supercritical CO2 is an exceptional solvent and is used to extract fragrances and color from flowers and plants. This method calls for unique tools and equipment and is executed under high pressure.


Solid CO2 or dry ice is utilized applied in many different ways as a coolant. When liquid CO2 is sent through a high pressure line and discharged through special nozzles, it immediately becomes 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 for long road transportation.

Extremely small pieces of dry ice are (about the size of a grain of rice) employed as an abrasive to remove coatings from surfaces without hurting the surface itself by blasting the rice size pellets through a blasting lance. This is prevalent in the aircraft industry where the airplane’s bodies need to remain unharmed and not be damaged from sand blasting. An additional benefit is that the removed coating does not require separating from the abrasive as the pellets sublimate to CO2 gas leading to a cleanup that is quite easy.

Referring to CO2 as a super-gas may be debatable, but it is without a doubt the most versatile gas available in the industrial gas market.

To learn more about how you can get carbon dioxide in Indianapolis for any of your specialty gas operations, call American Welding & Gas, Inc. at or at

John Segura, PE

About the Author

John Segura is a licensed Professional Engineer and a well-rounded executive in the industrial gas business. He has worked for over 30 years with both domestic and international experience handling operations, marketing, and sales. Segura has led teams of engineers and technicians as an R & D manager for major gas companies. His work directed him to lead 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.