Introduction of working principle of portable combustible gas detector
Combustible gas detector is a detector which is installed and used in industrial and civil buildings and responds to the concentration of single or multiple combustible gases. The catalytic combustible gas detector and semiconductor combustible gas detector are the most commonly used in daily life.
Semiconductor combustible gas detectors are mainly used in restaurants, hotels, family workshops and other places where gas, natural gas and liquefied gas are used; Catalytic combustible gas detectors are mainly used in industrial places where combustible gases and vapors are emitted.
Catalytic combustible gas detector is to measure the concentration of combustible gas by using the resistance change of refractory metal platinum wire after heating. When combustible gas enters the detector, it causes oxidation reaction (flameless combustion) on the surface of platinum wire, and the heat generated by it increases the temperature of platinum wire, while the resistivity of platinum wire changes. Therefore, when encountering high temperature and other factors, the temperature of platinum wire changes, while the resistivity of platinum wire changes, and the detected data also changes.
The semi-conductor combustible gas detector uses the change of semiconductor surface resistance to measure the concentration of combustible gas. The gas-sensitive semiconductor element with high sensitivity used in semiconductor combustible gas detector, when it encounters combustible gas in working state, the semiconductor resistance drops, and the drop value has a corresponding relationship with the concentration of combustible gas.
The combustible gas detector consists of two parts: detection and detection. The principle of the detection part is that the sensor of the instrument uses a detection element, a fixed resistor and a zero-setting potentiometer to form a detection bridge. The bridge uses platinum wire as the carrier catalytic element. After being electrified, the temperature of the platinum wire rises to the working temperature, and air reaches the surface of the element by natural diffusion or other means.
When there is no combustible gas in the air, the output of the bridge is zero; When combustible gas is contained in the air and diffused to the detection element, flameless combustion is generated due to catalysis, so that the temperature of the detection element is increased, the resistance of the platinum wire is increased, and the bridge is out of balance, thus a voltage signal is output, and the voltage signal is proportional to the concentration of combustible gas. The signal is amplified and converted to analog and digital, and the concentration of combustible gas is displayed by the liquid display.
Electrochemical gas detector is a gas detector using electrochemical sensors. Because many combustible gases have electrochemical activity and can be electrochemically oxidized or reduced, and the current generated by this reaction is proportional to the concentration of the gas that reacts, the composition and concentration of the gas can be detected through this kind of reaction.
