Working principle of portable combustible gas detector
Combustible gas detectors are detectors installed and used in industrial and civil buildings that respond to single or multiple combustible gas concentrations. There are two types of catalytic flammable gas detectors and semiconductor flammable gas detectors that are most used in daily life.
Restaurants, guesthouses, home production rooms and other places that use gas, natural gas, and liquefied petroleum gas mainly use semiconductor-type flammable gas detectors; industrial places that emit flammable gas and flammable steam mainly use catalytic-type flammable gas detectors.
The catalytic combustible gas detector uses the resistance change of the refractory metal platinum wire to measure the concentration of combustible gas. When the combustible gas enters the detector, it will cause an oxidation reaction (flameless combustion) on the surface of the platinum wire, and the heat generated will increase the temperature of the platinum wire, and the resistivity of the platinum wire will change. When the temperature of the platinum wire changes, the resistivity of the platinum wire changes, and the detected data also changes.
The semiconductor-type flammable gas detector uses the change of semiconductor surface resistance to measure the concentration of flammable gas. The semiconductor combustible gas detector uses a gas-sensitive semiconductor element with high sensitivity. When it encounters combustible gas in the working state, the resistance of the semiconductor will drop, 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-adjustment potentiometer to form a detection bridge. The bridge uses platinum wire as the carrier catalytic element. After electrification, the temperature of the platinum wire rises to the working temperature, and the air reaches the surface of the element by 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, due to the catalysis to produce flameless combustion, the temperature of the detection element rises, and the resistance of the platinum wire increases. , so that the bridge is out of balance, so that there is a voltage signal output, the magnitude of this voltage is proportional to the concentration of flammable gas, the signal is amplified, converted from analog to digital, and the concentration of flammable gas is displayed through the liquid display.
Electrochemical gas detectors are gas detectors using electrochemical sensors. Since many gases are electrochemically active, they can be electrochemically oxidized or reduced, and the current generated by this reaction is proportional to the concentration of the gas that reacts. , so the composition and concentration of the gas can be detected through this type of reaction.
