The core of portable gas detectors lies in their precise sensor technology, which achieves accurate detection of specific gases through different principles.

Electrochemical sensors: For gases such as oxygen, carbon monoxide, hydrogen sulfide, etc., electrochemical sensors are commonly used. Taking carbon monoxide detection as an example, the sensor contains an electrolyte and two electrodes (working electrode and counter electrode) inside. When carbon monoxide gas enters the sensor through the breathable membrane, oxidation reaction occurs on the surface of the working electrode, resulting in electron transfer and the formation of a current signal related to carbon monoxide concentration. By accurately measuring and calibrating the current, the gas concentration can be determined. This type of sensor has high selectivity and sensitivity for specific gases, and can detect gas concentrations as low as a few ppm (parts per million). It is widely used for monitoring toxic and harmful gas leaks, such as preventing the risk of carbon monoxide poisoning in industrial environments.

Catalytic combustion sensor: mainly used to detect combustible gases such as methane, propane, etc. The principle is based on the combustion characteristics of gas under the action of a catalyst, and the sensor consists of a Wheatstone bridge and an active catalyst element. When combustible gases come into contact with the catalyst surface, flameless combustion occurs, releasing heat that raises the temperature of the sensor, causing a change in resistance and an imbalance in the bridge, resulting in a voltage signal that is processed to correspond to the gas concentration. For example, in the petroleum and petrochemical industry, portable gas detectors use this principle to monitor combustible gas leaks in real time, ensuring operational safety. Once the gas concentration exceeds the standard, they quickly alert personnel to evacuate and take emergency measures.

Semiconductor sensor: The characteristic of resistance change caused by the adsorption of gas by semiconductor materials. When the measured gas molecules adsorb on the semiconductor surface, it causes a change in the surface carrier concentration, which in turn changes the resistance. The gas concentration can be calculated by detecting the change in resistance.

Infrared sensor: works based on the absorption characteristics of different gases towards specific wavelengths of infrared light. The light source emits infrared light, which is received by the detector after passing through the gas chamber. Due to the absorption of specific wavelengths of infrared light by the gas, the transmitted light intensity decreases. The gas concentration is determined by analyzing the changes in light intensity. Infrared sensors have good stability and long lifespan, and can detect various gases such as carbon dioxide and methane. They can detect the concentration of carbon dioxide in poorly ventilated spaces to evaluate air quality, or play an important role in monitoring harmful gases such as ammonia and sulfur dioxide in agricultural greenhouses to promote crop growth.

Precautions for using portable gas detectors:

1. Daily maintenance: Regularly clean the instrument to keep it dry and clean; Regularly inspect and replace the built-in filter element; When not in use for a long time, it should be turned off and stored in a dry, dust-free, and suitable temperature environment.

2. Operating standards: Avoid instrument collisions, drops, and severe vibrations to prevent damage to sensors; Waterproof and dustproof, preventing moisture and impurities from entering the instrument; Strictly follow the instructions to avoid accidental operation.

3. Environmental requirements: Pay attention to the influence of environmental factors such as temperature, humidity, and wind direction on the test results, and avoid using under special environmental conditions; When used in high temperature and high humidity environments, filter and dehumidify first.

4. Calibration and maintenance: Regularly calibrate and maintain the instrument to ensure the accuracy of the test results; Sensors should be used within their validity period and replaced promptly after expiration.

5. Safety precautions: When using the instrument, appropriate protective equipment should be worn, and relevant safety standards and operating procedures should be followed; Before entering the dangerous area, the human body should first release static electricity.

6. Troubleshooting: When the instrument malfunctions, it is strictly prohibited to disassemble and repair it without authorization. Professional personnel should be responsible for maintenance.