Gas detection system is a sensor device used to detect the presence of harmful gases in the air. These safety devices are often accompanied by an automated alarm that alerts the people in the area of gas leakage, thus enabling them to leave the area of gas leakage.
The discovery of the harmful impact of some gases on human and animal health raised the need of creating a gas detection system. The coal miners in the early 19s and 20s were known to bring canary birds down in the tunnel to detect the presence of carbon dioxide or carbon monoxide. The bird would stop singing with a rise in the number of harmful gases and would die soon. This alerted the miners to evacuate the mine as soon as possible.
Sir Humphry Davy of England invented the first-ever industrial gas detector in the year 1815 to detect the presence of Methane in coal mines. It had an oil flame adjusted to a particular height in the fresh air and a glass sleeve with a mesh frame arrestor to prevent any ignition. The flames got raised or low on the presence of Methane or in low oxygen.
The first gas detecting device was invented by Dr. Oliver Johnson (founder of Johnson-Williams Instruments 1928 in Palo Alto) under deep research to control explosions in fuel storage tanks. Since then, JW- instruments have invented varied ranges of gas detecting devices.
There is a varied range of gas detectors on the basis of their working mechanism, as mentioned below:
-Electrochemical: These gas detectors work by diffusion of gases through a porous membrane to an electrode where it is either chemically oxidized. The value of current generated is calculated by the amount of gas oxidized at the electrode. This gives exact details of the concentration of gas. It is mainly used in sectors like gas turbines, chemical plants, underground gas storage facilities, etc.
-Catalytic Beads: These sensors are used to detect the presence of explosive gases with concentrations between the lower explosion limit (LEL) and upper explosion limit (UEL). It works on the principle of the Wheatstone bridge where a rise in temperature due to catalytic combustion by oxidized compounds causes voltage deflection. The rise in concentrations of harmful gases is detected by this fluctuation in sensor voltage.
-Photoionization: A high-photon-energy UV lamp is used in these detectors to ionize chemicals in the sampled gas. The low-value ionization energy of the compound than that of a photon lamp causes the ejection of an electron. The value of current obtained is directly proportional to the concentration of gases present outside the lamp. It is mainly used for industrial safety and environmental safety.
-Infrared Imaging: These sensors work on the principle of spectral changes in the atmosphere. All the compounds in gases that come in the infrared imaging range are detected as well as the source of gas is also identified.
-Semi-Conductors: The chemical reaction between the gas and metal oxide semiconductor detects the presence of gas. The metal oxide used is generally tin dioxide. It is used for the detection of carbon monoxide, sulfur dioxide, hydrogen sulfide, and ammonia in the environment.
There are a variety of gas detectors that are used in households to detect any leakage in natural gas cylinders, pipelines butane tanks, or any other combustible gas.
