How does a portable combustible gas detector work?
Combustible gas detectors are detectors installed and used in industrial and civil buildings that respond to single or multiple combustible gas concentrations. The two types that are most commonly used daily are catalytic flammable gas detectors and semiconductor flammable gas detectors.
Semiconductor-type flammable gas detectors are mainly used in restaurants, hotels, home studios and other places that use gas, natural gas, and liquefied gas; industrial places that emit flammable gases and combustible steam mainly use catalytic-type flammable gas detectors.
The catalytic combustible gas detector uses the resistance change of the refractory metal platinum wire after heating to measure the concentration of combustible gas. 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 resistivity of the platinum wire changes. Therefore, when encountering factors such as high temperature, When the temperature of the platinum wire changes, the resistivity of the platinum wire changes, and the detected data will also change.
Semiconductor combustible gas detectors use changes in semiconductor surface resistance to measure combustible gas concentrations. Semiconductor flammable gas detectors use gas-sensitive semiconductor components with high sensitivity. When it encounters combustible gases in its working state, the semiconductor resistance drops, and the drop value has a corresponding relationship with the concentration of combustible gases.
The flammable 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-adjusting potentiometer to form a detection bridge. The bridge uses platinum wire as a carrier to catalyze the element. After power is applied, the temperature of the platinum wire rises to the operating temperature, and the air reaches the surface of the element through natural diffusion or other methods.
When there is no flammable gas in the air, the output of the bridge is zero; when the air contains flammable gas and diffuses to the detection element, flameless combustion occurs due to catalysis, which increases the temperature of the detection element and increases the resistance of the platinum wire. , causing the bridge circuit to lose balance, thereby outputting a voltage signal. The magnitude of this voltage is proportional to the concentration of flammable gas. The signal is amplified, analog-to-digital converted, and the concentration of flammable gas is displayed through the liquid display.
Electrochemical gas detectors are gas detectors that use electrochemical sensors. Since many gases are electrochemically active and can be electrochemically oxidized or reduced, the current generated by this reaction is proportional to the concentration of the reacted gas. , so the composition and concentration of the gas can be detected through this type of reaction.
