Carbon Dioxide (CO2)

Carbon dioxide (CO2) is an important gas with numerous connections to biological, atmospheric, oceanic, environmental, experimental, and industrial processes.

It exists in the earth’s atmosphere at an approximate concentration of 0.0390% by volume or 390ppm. In May 2013, atmospheric concentration reached 0.04% or 400ppm for the first time in possibly millions of years. Carbon dioxide is a greenhouse gas because it inhibits outward thermal radiation from the earth – in other words, it traps heat.

Sources of CO2 are numerous. Natural sources include volcanoes, organic matter combustion, respiration of living things, fermentation, and photosynthesis. Anthropogenic, or unnatural, sources primarily include fossil fuel burning, power generation, transportation, heating buildings & homes, and industrial processes such as iron & steel, cement, and chemical production. Deforestation also contributes to CO2 accumulation by removing a critical natural CO2 sink.


Gas Analysis

Carbon dioxide is a gas of interest in many analytical applications. Infrared detectors can be used to measure CO2 because it is an excellent absorber of infrared energy. Carbon dioxide can be measured in percent (%) and parts per million (ppm) depending on the requirements of the application.

The off-gas stream that results from steel-making applications, such as EAFs, contains carbon in the form of CO2. Some metal heat treat applications utilize CO2 as a part of the carbon-containing atmosphere. The CO2 levels can be dynamically measured in these cases and is usually present at percent levels. Measuring CO2 in these applications may be important for energy balance, end-point determination, and maintaining product hardness and quality.

Carbon dioxide is also a by-product of combustion. In combustion applications, such as boilers, furnaces, and heaters, CO2 measurement can be used with temperature and oxygen content to evaluate efficiency and burner performance. To tune a boiler for maximum efficiency and fuel savings, a portable CO2 analyzer with measurement in the in the percent range is helpful.

Carbon dioxide is also a by-product of three of the four basic bio-chemical stages of landfill gas production. Measuring CO2 and methane (CH4) in landfill gas is useful for determining the gas quality. If the produced gas is burned in an engine, the exhaust products will also contain CO2. Measuring the CO2 in the engine exhaust using a flue gas analyzer may also be useful in evaluating engine efficiency.

In the agricultural and food storage industries, CO2 plays a critical role in the growth of plants and the storage of produce. A controlled atmosphere of low oxygen and elevated CO2 is used to disinfect produce, prolong freshness, and control insect pests. Maintaining adequate CO2 levels in greenhouses will ensure proper plant growth and productivity.

The toxicity of CO2 is one reason why a reliable air quality monitor may be required in a facility. Furnaces, boilers, combustion engines, controlled atmospheres, and other processes may give off dangerous amounts of CO2. The Permissible Exposure Limit (PEL, by Time-Weighted Average as stated by OSHA) of CO2 gas is currently 5,000 ppm over 8 hrs. Therefore, an air quality monitor that can provide analysis at the ppm level is important.


Carbon dioxide is used in some fire suppression systems to extinguish fires in engine rooms, ship holds, electrical areas, dust collectors, and other areas with specific hazards. Fire testing and investigation applications may require the simultaneous analysis of CO2 at various strata in a space during a controlled fire event. A modified portable CO2 analyzer with three separate CO2 channels is available from Nova for this purpose. See this Nova blog post.

In gasification applications, CO2 is often used as an agent during the reduction phase. Carbon dioxide and water vapour are passed over a bed of hot char and are converted to CO and H2 which can be burned later as fuel gases. Measuring the CO2 in the produced gas or ‘syngas’ can help evaluate gasifier operation.

Carbon Dioxide Gas Analyzer Models

Nova has capability for CO2 measurement using the infrared methodology. Our analyzers can be supplied with a built-in sample pump or a pressure regulator to suit most applications. Portable and permanent continuous models are available. Many of the analysers shown here also measure other gases besides CO2.

Here are our carbon dioxide analyzers:

Carbon Monoxide Analyzers

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