Portable combustible gas detector operation
Combustible gas detector is a detector installed and used in industrial and civil buildings that responds to the concentration of single or multiple combustible gases. The most commonly used types in daily life are catalytic combustible gas detectors and semiconductor combustible gas detectors.
Semi conductive combustible gas detectors are mainly used in places such as restaurants, hotels, and home workshops where gas, natural gas, and liquefied gas are used; Catalytic combustible gas detectors are mainly used in industrial places that emit combustible gases and vapors.
Catalytic combustible gas detector uses the resistance change of refractory metal platinum wire after heating to determine the concentration of combustible gases. When combustible gas enters the detector, it causes oxidation reaction (flameless combustion) on the surface of the platinum wire, and the heat generated increases the temperature of the platinum wire, causing a change in its electrical resistivity. Therefore, when encountering high temperature and other factors, the temperature of the platinum wire changes, and the electrical resistivity of the platinum wire changes, resulting in a change in the detected data.
The semiconductor type combustible gas detector uses the change in surface resistance of semiconductors to determine the concentration of combustible gases. The semiconductor combustible gas detector uses gas sensitive semiconductor components with high sensitivity. When it encounters combustible gas during operation, the semiconductor resistance decreases, and the decrease value corresponds to 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 potentiometer to form a detection bridge. The bridge uses platinum wire as a carrier for catalytic elements. After being powered on, the temperature of the platinum wire rises to the working temperature, and air reaches the surface of the element through natural diffusion or other means.
When there are no flammable gases in the air, the bridge output is zero; When combustible gases are present in the air and diffuse onto the detection element, flameless combustion occurs due to catalytic action, causing the temperature of the detection element to rise and the resistance of the platinum wire to increase, causing the bridge circuit to lose balance. As a result, a voltage signal is output, which is proportional to the concentration of the combustible gas. The signal is amplified, analog-to-digital converted, and displayed on a liquid display to show the concentration of the combustible gas.
Electrochemical gas detector is a gas detector that uses electrochemical sensors. Due to the electrochemical activity of many gases, they can be electrochemically oxidized or reduced, and the current generated by this reaction is proportional to the concentration of the gas undergoing the reaction. Therefore, the composition and concentration of the gas can be detected through this type of reaction.
