Conventional Detection Methods of Toxic & Hazardous Gas Detectors
There are multiple gas detection technologies available when using gas detectors to measure toxic gases. At present, however, no single technology can achieve rapid, low-cost and highly accurate measurement of specific toxic gases. Therefore, various factors need to be comprehensively considered when selecting an appropriate detection method for toxic gases.
① Colorimetric Tube Measurement Technology In addition to toxic gas alarm monitors, colorimetric tube technology is still widely adopted for testing toxic and hazardous gases in industrial and environmental protection fields. This measuring method based on chemical color reaction has the greatest advantage of making up for the limitation when no matching sensor is available for instrumental detection.
② Electrochemical Sensors Electrochemical sensors are the most common and mature technology for toxic and hazardous gas detection in portable gas detectors. They feature compact size, low power consumption, excellent linearity and repeatability, as well as relatively long service life.
③ Semiconductor Sensors The sensing elements of semiconductor sensors are made of metal oxide or metal semiconductor oxide materials. When interacting with target gases, surface adsorption or chemical reactions occur, which lead to changes in conductivity, volt-ampere characteristics or surface potential characterized by carrier movement. Such sensors can measure flammable gases at percentage concentration levels as well as toxic gases at ppm concentration levels.
④ Ionization Detectors Commercially available ionization detectors mainly include Photoionization Detectors (PID) and Flame Ionization Detectors (FID). They are the most widely used toxic gas detectors equipped on gas chromatographs. When manufactured as standalone instruments, PID and FID become the mainstream testing solutions for volatile organic compounds (VOCs).
