Why the Grade of CO2 Gas you are Using is Important

One of the things we love to do at CO2Meter is talk about the new applications customers have shared with us by phone or email. We always say “now we have heard it all”, and then, someone calls with a new application.

The one question we rarely hear from customers but that is hyper-critical to success is “what food, beverage, or medical grade CO2 should I be using”. That’s right – there are different grades or “purities” of CO2 that are produced and used.

Does Beverage Grade CO2 Matter?

Specialty gases have become key components for almost every industry, including beverage, restaurant, scientific, incubation, agriculture, safety and others. The grade or "purity" of the gases can be influenced by elements such as oxygen, moisture content, total hydrocarbons, nitrogen, and carbon monoxide - to name a few.

In the U.S. specifically, beverage grade CO2 will almost always be at least 99.90% pure; many other molecules can compromise the other 0.10% , including water, oxygen, and hydrocarbons such as benzene, acetaldehyde, and other molecules. 

CO2 purity for beverage grade gases is now also mandated by the Food and Drug Administration. The FDA regulations allows for the other .09% of the gas to be made up of other hydrocarbons.

When you take a look at food grade gases, their are specific standards and regulations in terms of a minimum purity criteria for gases when incorporated into food additives. One example can be found by the European Commission (EC) who states a minimum purity criteria for food grade gases such as CO2, N2 and O2.  Each having to adhere to a number code and must be of high purity.  

Food grade CO2 is not meant for human consumption. For that, you should use Beverage Grade, which is more pure than Medical Grade. Both major soft drink companies have Beverage Grade as their minimum guideline. Food Grade CO2 is recognized more as a "dirty gas" that isn't tested for several carcinogens.

Here are a few other helpful hints to ensure you are gaining the highest grade CO2 when looking at beverage application:

• For carbonated beverages, specify and use either ISBT Purity Grade (“beverage grade”) CO2 or Food-Grade CO2.
• Suppliers should provide a certificate of analysis (COA) upon delivery of CO2 to document that the actual lot meets the required purity specifications.
• Periodically audit the quality management practices of your CO2 supplier and request that they verify their quality through an independent ISO-certified lab.
• Ask your supplier what proportion of their CO2 supply derives from ethanol production, petrochemical production, or other sources (this may allow you to assess supply risk).
• Ask your supplier what steps they are taking to ensure that beverage grade CO2 quality and quantity requirements will be met in the event of supplier feedstock source changes.

Then ask yourself these simple questions:

1. Do you know what grade gas you are receiving from your gas supplier? 
2. Have you ever thought to ask them?
3. IS your gas supplier providing you with a certificate of purity?

What is Medical Grade CO2 used for?

When it comes to using medical grade carbon dioxide these applications typically encompass hospitals, scientific research, or laboratory discoveries. For instance, medical grade CO2 is critical when insufflating patients during invasive surgeries like laparoscopy, arthroscopy, endoscopy, or cryotherapy. 

Table: CO2 Purity Grades

This table lists CO2 purity in descending order.

The biggest difference between the grades are the amounts and kinds of impurities that are allowable in the CO2.  

As you ascend the list the amount of impurities like ammonia, benzene, oxygen, carbon monoxide, and others allowed to be in specific grades of gas are lessened. While nobody wants to ingest benzene or ammonia those hydrocarbons are far more dangerous when working with lasers than with lagers.

For example, in laser applications the impact of the speed and the quality of the laser cut is extremely dependent upon the quality and purity of the gas. Impure oxygen can have a huge impact on the final product produced by the laser cut. The two main gases which need to be incorporated are oxygen and nitrogen, with purities of 99.95% stated to increase the speed and productivity. 

Industrial applications like welding utilize 99.5% pure CO2. In welding, higher purity CO2 produces better welds because the process is heating less impurities in the process. Those impurities have been found to produce less stable welds.

If you are unsure of your gas quality or call your suppliers analysis in to question you can contact an outside laboratory for third party testing services. You can contact www.airbornelabs.com as an example.

Also consider testing the water in your process as well. Brewers and vintners are keenly aware that water purity is just as important to end quality as the gas that they are using in your process. In fact, hydrocarbons like benzene are more likely to appear in the water in your process then in the gas you are using.          

If you are interested in further details about beverage gas and its chemical composition please visit the International Society of Beverage Technologist, which CO2Meter, Inc. is a member of, at www.bevtech.org.

Gases have become such an integral part of many industries and applications, and understanding the importance of gas purity, trace-ability in its use, and specific regulation/standards is crucial.