Portable gas detector working principle
Background:
Portable gas detector is a kind of instrument that can quickly detect the gas concentration in the environment in the field. It can be used in industry, environmental protection, health, military and other fields. This paper introduces the classification, working principle, application scenario and development trend of portable gas detector.
Classification of portable gas detector
Portable gas detector can be divided into various types according to the detection principle, detection gas type, detection method, sensor type and so on.
Catalytic combustion type gas detector: This detector mainly uses catalytic combustion type sensor, can detect toxic and harmful gases, such as carbon monoxide, hydrogen sulfide, methane, etc.
Electrochemical gas detector: This detector mainly uses electrochemical sensor, can detect a variety of gases, such as oxygen, carbon dioxide, nitric oxide and so on.
Semiconductor gas detector: This detector mainly uses semiconductor sensor, can detect toxic gas, flammable gas and so on.
Optical gas detector: This detector mainly uses optical sensors, can detect toxic gas, combustible gas, oxygen and so on.
Adsorbent type gas detector: This detector mainly uses adsorbent type sensor, can detect a variety of toxic and harmful gases, such as hydrogen sulfide, methane, nitrous oxide, etc.
Portable gas detector working principle
The portable gas detector works by converting the gas concentration into an electrical output based on the response characteristics of the gas sensor. Gas sensor is the core component of portable gas detector. Its different types and structures lead to different detection principles.
1. Catalytic combustion type gas detector: This detector mainly uses catalytic combustion type sensor. The sensor is composed of non-selective infrared absorption pool, current-carrying electrode, electronic control circuit, electronic module and sensing element. When poisonous and harmful gases enter the sensor, the gas molecules react with the catalyst on the surface of the sensor element, and the heat generated makes the resistance value of the sensor element change. The electronic control circuit converts the resistance value change into electrical signal, so as to realize the gas detection.
2. Electrochemical gas detector: This detector mainly uses electrochemical sensor, sensor by working electrode, reference electrode, protection electrode, shell, etc. When the toxic and harmful gas enters the sensor, the gas molecules adsorb or desorption on the electrode surface, changing the electrode potential, which causes the change of the resistance value of the sensor element, the electronic control circuit converts the change of the resistance value into electrical signal, so as to realize the gas detection.
3. Semiconductor gas detector: This detector mainly uses semiconductor sensor, sensor by P type semiconductor, N type semiconductor, metal electrode, isolation layer, reaction gas contact layer, heating control circuit and so on. When the toxic and harmful gas enters the sensor, the gas molecules adsorb or desorption on the surface of the metal electrode, changing the voltage of the semiconductor wafer, which causes the change of the resistance value of the sensor element, and the electronic control circuit converts the change of the resistance value into electrical signal, so as to realize the gas detection.