Classification of gas detectors and their respective advantages and disadvantages after classification
Date: 2014-01-16Read: 8
gas detectorMainly using gas sensors to detect the types of gases present in the environment, gas sensors are sensors used to detect the composition and content of gases.
gas detectorClassification and their respective advantages and disadvantages:
1.Gas detector - semiconductor typeIt is manufactured using the principle that the conductivity of some metal oxide semiconductor materials changes with the composition of the ambient gas at a certain temperature. For example, an alcohol sensor is prepared based on the principle that when tin dioxide encounters alcohol gas at high temperatures, its resistance will sharply decrease.
advantage：Semiconductor gas sensors can be effectively used for detecting many gases such as methane, ethane, propane, butane, alcohol, formaldehyde, carbon monoxide, carbon dioxide, ethylene, acetylene, vinyl chloride, styrene, acrylic acid, etc. Especially, this type of sensor is low-cost and suitable for the needs of civilian gas detection. The following semiconductor gas sensors are successful: methane (natural gas, biogas), alcohol, carbon monoxide (city gas), hydrogen sulfide, ammonia (including amines and hydrazine). High quality sensors can meet the needs of industrial testing. Industrial Scientific, American gas sensor
shortcoming：Poor stability and significant environmental impact; Especially, the selectivity of each sensor is not *, and the output parameters cannot be determined. Therefore, it is not suitable for places that require accurate measurement.
2.Gas detector - combustion typeThis type of sensor is prepared with a high-temperature resistant catalyst layer on the surface of a platinum resistor. At a certain temperature, combustible gases catalyze combustion on its surface. Combustion is a function of the concentration of combustible gases as the temperature of the platinum resistor increases and the resistance changes.
advantage：Catalytic combustion gas sensors selectively detect combustible gases: anything that cannot be burned has no response from the sensor. Catalytic combustion gas sensors have accurate measurement, fast response, and long lifespan. The output of sensors is directly related to the explosion hazard of the environment and is a dominant type of sensor in the field of safety detection.
shortcoming：Within the range of flammable gases, there is no selectivity. Working in a dark environment poses a risk of ignition and explosion. Most organic vapors have a toxic effect on sensors.
3.Gas detector - thermal conductivity pool typeEach gas has its own specific thermal conductivity, and when there is a significant difference in thermal conductivity between two or more gases, a thermal conductivity element can be used to distinguish the content of one component. This type of sensor has been widely used for detecting hydrogen, carbon dioxide, and high concentration methane.
This gas sensor has a narrow application range and many limiting factors.
4.Gas detector - electrochemical typeA significant portion of its flammable, toxic, and harmful gases have electrochemical activity and can be electrochemically oxidized or reduced. By utilizing these reactions, gas composition can be distinguished and gas concentration can be detected. Electrochemical gas sensors are divided into many subcategories:Original battery type gas sensorConstant potential electrolytic cell gas sensorBattery type gas sensorExtreme current gas sensor.
5.Gas detector - infraredMost gases have characteristic absorption peaks in the mid infrared region. By detecting the absorption situation of the characteristic absorption peak position, the concentration of a certain gas can be determined.
This type of sensor used to be a large analytical instrument, but in recent years, with the development of technology-based sensor industry, the volume of this sensor has decreased from a giant of 10 liters and 45 kilograms to around 2 milliliters (thumb size). The use of infrared detectors that do not require modulation of the light source enables the instrument to have no mechanical moving parts and achieve maintenance free operation. Infrared gas sensors can effectively distinguish the types of gases and accurately measure gas concentrations,Successfully used for detecting carbon dioxide and methane.