Carbon Dioxide

Carbon dioxide is a chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom and is knows as the formula CO2. Carbon dioxide is colorless. At low concentrations, the gas is odorless. At higher concentrations it has a sharp, acidic odor.
Carbon dioxide is used by plants during photosynthesis to make sugars, which may either be consumed in respiration or used as the raw material to produce other organic compounds needed for plant growth and development.
Carbon dioxide is generated as a by-product of the combustion of fossil fuels or the burning of vegetable matter, among other chemical processes. As of March 2009, carbon dioxide in the Earth's atmosphere is at a concentration of 387 ppm by volume. Atmospheric concentrations of carbon dioxide fluctuate slightly with the change of the seasons, driven primarily by seasonal plant growth.
Carbon Dioxide Characteristics
CAS No. 124-38-9
Chemical formula CO2
Vapour density 1.53 (air = 1)
Safe Work Australia ES TWA 5,000 ppm
12,500 ppm in underground coal mines (1)
STEL 30,000 ppm
Flammable limits LEL --
UEL --
Chemical/physical properties Carbon dioxide is a colourless and odourless gas but has a faint acidic taste and, at high concentrations, can be irritating to the mucous membranes and eyes due to the formation of carbonic acid when it dissolves in water. 
Hazardous properties Carbon dioxide has a stimulatory effect on the respiratory centre in the brain, increasing the breathing rate at raised concentrations. Prolonged exposure to elevated concentrations (e.g. 10,000 ppm) also has an effect on metabolism, leading to electrolyte imbalance and acidosis (lowering of blood pH).
Symptoms of exposure to high concentrations (e.g. 50,000 ppm) are shortness of breath and headache. People working in high concentrations of CO2 (e.g. 30,000 ppm in submarines) suffer only slight effects provided the oxygen concentration is maintained at “normal” levels.(2)
Occurrence/Uses Carbon dioxide occurs naturally in the atmosphere at about 400 ppm (up from about 300 ppm 50 years ago) and is a produced during the combustion, fermentation and decay of organic (carbon containing) materials. It is also a product of animal and plant respiration. 
CO2 is also an important greenhouse gas due to its ability to absorb infrared radiation thus helping to heat the atmosphere.
Carbon dioxide gas is used to carbonate beverages, to control the pH in swimming pool water and as an additive to greenhouse atmospheres to increase plant growth. It occurs during the fermentation process in making wine and beer. In its solid form (dry ice) it is used for refrigeration purposes.
Detectors available Infra-red (NDIR) (0 – 5 % by volume)
Gas detector tube (100 ppm – 20 % by volume)
Suggested alarm levels Application dependant, but generally:
Lo: 5,000 ppm (0.5 % by volume)
Hi: 30, 000 ppm (3.0 % by volume)
Professional advice strongly recommended.
Notes (1) This ES applies ONLY to underground coal mines where CO2 emission from the coal strata occurs naturally. (Refer to for further details).
(2) In situations where CO2 can be present at elevated concentrations and O2 levels might fall below 18% by volume, it is recommended to monitor both CO2 and O2. Monitoring either gas alone may not ensure complete protection.

Air-Met offers a wide range of Carbon Dioxide detectors. Depending on the application we provide portable, fixed and applications for the bevarage industry. Contact Air-Met today for more information

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