How does a fixed SO2 gas detector work?

User:JXCTUpload time:Aug 23 2023


Sulfur dioxide (SO2) is a toxic gas that is produced by various industrial processes, such as the burning of fossil fuels and the smelting of ores. Exposure to high levels of SO2 can have detrimental effects on human health and the environment. To ensure the safety of workers and the surrounding environment, fixed SO2 gas detectors are used to continuously monitor the concentration of SO2 in the air. This article will explore the working principles of a fixed SO2 gas detector.

Working Principles:

Gas Sensing Technology: Fixed SO2 gas detectors utilize gas sensing technology to detect and measure the concentration of SO2 in the air. The most commonly used gas sensing technology for SO2 detection is electrochemical sensing. In this technology, an electrochemical cell is used as the sensing element.

Electrochemical Cell: The electrochemical cell consists of three main components: the working electrode, the counter electrode, and the reference electrode. The working electrode is made of a material that is sensitive to SO2 gas. When SO2 gas comes into contact with the working electrode, a chemical reaction occurs, causing a change in the electrical properties of the electrode.

Ionization and Oxidation: When SO2 gas contacts the working electrode, it undergoes ionization and oxidation reactions. The SO2 gas is ionized by releasing electrons, which creates a current flow in the electrochemical cell. The oxidation reaction converts SO2 gas into sulfuric acid (H2SO4) or sulfurous acid (H2SO3), depending on the specific electrochemical cell design.

Current Measurement: The current generated by the electrochemical cell is directly proportional to the concentration of SO2 gas in the air. The gas detector measures this current and converts it into a digital signal, which is then displayed on a screen or transmitted to a control system for further analysis.

Calibration and Maintenance: To ensure accurate and reliable measurements, gas detectors require regular calibration and maintenance. Calibration involves exposing the gas detector to a known concentration of SO2 gas and adjusting the sensor's response accordingly. Maintenance includes cleaning the sensor, replacing any worn-out components, and checking for any drift in the sensor's performance.

Alarm System: gas detectors are equipped with an alarm system to alert users when the concentration of SO2 gas exceeds a predefined threshold. The alarm system can consist of visual indicators, such as flashing lights or LED displays, and audible alarms, such as sirens or buzzers. Some advanced gas detectors can also transmit alarm signals to a central control system or trigger automatic shutdown procedures in the event of high SO2 gas levels.


Fixed SO2 gas detectors play a crucial role in ensuring the safety of workers and the environment by continuously monitoring the concentration of SO2 gas in the air. Through the use of electrochemical sensing technology, these detectors can accurately measure the concentration of SO2 gas and provide timely alarms in case of high levels. Regular calibration and maintenance are essential to maintain the accuracy and reliability of the gas detector. By employing gas detectors, industries can effectively mitigate the risks associated with SO2 gas exposure and ensure a safe working environment.