IR GAS DETECTOR

The infrared (IR) method of gas detection relies on the IR absorption characteristics of gases to determine their presence and concentration. IR gas detectors consist of an IR light source (transmitter) and light detector (receiver) to measure the intensity both at the absorption wavelength and a non-absorbed wavelength. If gas is present in the optical path, it will affect the intensity of light transmitted between the light source and the detector. This change in intensity provides the data for determining that a specific gas or type of gas is present. This method works only for gases that can absorb infrared radiation. Most hydrocarbon based gases absorb IR radiation at around 3.4 micrometers, which is transparent to both water and carbon dioxide vapors.Combustible IR gas detection can take one of two forms: either the point detector or the open path detector. The primary difference between point detectors and open path is the size of the IR path and its relationship to the gas/vapor sample source. The self-contained point detector has a smaller IR path than the open path detector, and is used to monitor fixed areas of space. The open path detector usually consists of a separate transmitter and receiver, which monitor much larger areas of space. Consequently, in some instances a single open path detector serves the function of multiple point detectors.