Portable combustible gas detector working principle
Combustible gas detector is a detector installed and used in industrial and civil buildings that responds to single or multiple combustible gas concentrations. The two most commonly used types in daily life are catalytic combustible gas detectors and semi conductive combustible gas detectors.
Semiconductive combustible gas detectors are mainly used in places such as restaurants, hotels, and home production rooms that use gas, natural gas, and liquefied gas; Industrial sites that emit combustible gases and vapors mainly use catalytic combustible gas detectors.
A catalytic combustible gas detector uses the resistance change of a refractory platinum wire heated to measure the concentration of combustible gases. When combustible gas enters the detector, it causes an oxidation reaction (flameless combustion) on the surface of the platinum wire. The heat generated increases the temperature of the platinum wire, and the electrical resistance of the platinum wire changes. Therefore, when encountering high temperatures and other factors, the temperature of the platinum wire changes, and the electrical resistance of the platinum wire changes, and the detected data also changes.
A semi conductive combustible gas detector uses changes in semiconductor surface resistance to measure 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 is related 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 detection elements, fixed resistors, and a zero potentiometer to form a detection bridge circuit. The bridge circuit uses platinum wire as the carrier catalytic element. 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 is no combustible gas in the air, the bridge output is zero; When combustible gases are present in the air and diffuse onto the detection element, flameless combustion is generated due to catalytic action, causing the temperature of the detection element to rise and the platinum wire resistance to increase, causing the bridge circuit to lose balance. As a result, a voltage signal is output, and the magnitude of this voltage is proportional to the concentration of combustible gases. The signal is amplified, analog-to-digital converted, and displayed on a liquid display to show the concentration of combustible gases.
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 that undergoes the reaction. Therefore, the composition and concentration of the gas can be detected through such reactions.
