A carbon dioxide recorder (or CO₂ recorder) is a machine that can record the level of

carbon dioxide Carbon dioxide is a chemical compound with the chemical formula . It is made up of molecules that each have one carbon atom covalent bond, covalently double bonded to two oxygen atoms. It is found in a gas state at room temperature and at norma ...

at different times. It is more sophisticated than a carbon dioxide detector which only has to indicate the presence of carbon dioxide. There are three main types of carbon dioxide recorder: chemical, physical, and electrical.

Mechanism

Chemical

The chemical carbon dioxide recorder, sucks the gas through a chemical that absorbs carbon dioxide. They include the Simmance combustion recorder; Hays automatic CO₂ recorder, and electroflo CO₂ recorder. The Arndt carbon dioxide recorder used a

potassium hydroxide Potassium hydroxide is an inorganic compound with the formula K OH, and is commonly called caustic potash. Along with sodium hydroxide (NaOH), KOH is a prototypical strong base. It has many industrial and niche applications, most of which utili ...

solution to absorb carbon dioxide. The Uehling recorder uses the chemical,

sodium hydroxide Sodium hydroxide, also known as lye and caustic soda, is an inorganic compound with the formula . It is a white solid ionic compound consisting of sodium cations and hydroxide anions . Sodium hydroxide is a highly corrosive base (chemistry), ...

to absorb the carbon dioxide, and measures the change in volume of the gas.

Physical

The physical carbon dioxide recorder, includes Webster CO₂ recorder. The Remarex carbon dioxide recorder uses vanes spinning in the gas under test and the air.

Electrical

Electrical recorders use a thermal conductivity method, where the resistance of a heated wire is measured.

Form

Carbon dioxide recorders can be handheld, or wall mount. They can have an audible or light indicator alarm if level is too high. Units can also measure

humidity Humidity is the concentration of water vapor present in the air. Water vapor, the gaseous state of water, is generally invisible to the human eye. Humidity indicates the likelihood for precipitation (meteorology), precipitation, dew, or fog t ...

and temperature.

Application

Carbon dioxide recorders have been used in schools and hospitals to determine whether enough fresh air is being circulated. A carbon dioxide recorder can be used to measure the composition of flue gas to check if combustion is at its most efficient. In agriculture, they can be used to measure levels of carbon dioxide in greenhouses, where the levels are deliberately elevated.

References

{{Reflist Gas sensors Carbon dioxide