Carbon DIoxide, CO2, or Super-Gas?

Fresno Oxygen & Welding Supplies/Barnes Welding Supply is a trusted supplier of carbon dioxide to Fresno and surrounding areas.

Most people outside the industrial gas industry recognize carbon dioxide, CO2, as the bubbles in soft drinks 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

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 that the combination of water and CO2 being dispensed from a fermentation process generated sparkling water which changed the taste of water and initiated the start of the soft drink industry.

One of the attributes of the gas that was found was its ability to be easily liquefied. This led to CO2 being 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 utlizied in all three of its phases – gas, liquid and solid.


Most of us in the industry associate CO2 with welding as a shielding gas and as a refrigerant in the food industry. There are also additional unique properties of CO2 that contribute to its versatility .

The best example is when CO2 creates carbonic acid after coming into contact with water. Although it is not the strongest acid, it is an acid nonetheless and is employed to modify 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 needs water to generate 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 atmospheric temperature. The result is that any process using liquid CO2 must be under pressure. Workers in the oil industry are aware of CO2 replacing water in enhanced oil recovery (EOR) where the liquid is combined with sand or sand like substance (proppant) and propelled through an oil well to recover oil that is stuck between rock layers. EOR is a blanket term to describe different applications but the most frequent is fracking. Here a propant is pushed into rocks rich with oil with the use of man-made devices. 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 increases the size of the fissure and leads to the recovery of more 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 applying turbulence to clean the wash. When the cycle is done, the dirt, grime and stain remover are separated from the liquid CO2. The liquid CO2 is then removed to be used again and the laundry is removed clean and dry since no water was used.

Every chemical (element or compound) has a state in which the three phases (gas, liquid and solid) have the same attributes and is reached through modification of temperature and pressure; this is referred to as the supercritical state. The supercritical state of CO2 can be created in a specifically designed processor. When in its fluid phase, CO2 is a great solvent and is utilized in the extracting of 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 applied in a wide variety of methods as a coolant. When liquid CO2 is moved through a high pressure line and discharged through special nozzles, it right away becomes CO2 snow and utilized to refrigerate and freeze food. Dry ice pellets act as a replacement for regular ice in tubs that hold perishables on long trips via roadways.

Very small cuts of dry ice are (about the size of a grain of rice) used as an abrasive to remove coatings from surfaces without harming the surface itself by shooting the rice size pellets through a blasting lance. This is popular 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 resulting in a simple cleanup.

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

To learn more about how you can obtain carbon dioxide in Fresno for any of your specialty gas operations, call Fresno Oxygen & Welding Supplies/Barnes Welding Supply at 559-341-4456 or at

John Segura, PE

About the Author

John Segura is a licensed Professional Engineer and a seasoned executive in the industrial gas world. He has worked for over 30 years with both domestic and international experience handling operations, marketing, and sales. 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 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.