Introduction to the working principle of 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 combustible gas detectors that are commonly used in daily life: catalytic combustible gas detectors and semiconductor combustible gas detectors.
Restaurants, guesthouses, home workshops and other places that use gas, natural gas, and liquefied petroleum gas mainly use semiconductor-type flammable gas detectors, and industrial places that emit flammable gases and flammable vapors mainly use catalytic-type flammable gas detectors.
The semiconductor-type combustible gas detector uses the change of semiconductor surface resistance to measure the concentration of combustible 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, and has detection and detection functions.
The principle of the detection part of the flammable gas detector 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 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, flameless combustion occurs due to catalytic action, which makes the temperature of the detection element rise and the resistance of the platinum wire increases. , making the bridge unbalanced;
Therefore, a voltage signal is output, and the magnitude of this voltage is proportional to the concentration of combustible gas. The signal is amplified, converted from analog to digital, and the concentration of combustible gas is displayed through the liquid display.
The principle of the detection part is that when the measured flammable gas concentration exceeds the limit value, the amplified bridge output voltage and the circuit detection set voltage;
Through the voltage comparator, the square wave generator outputs a set of square wave signals to control the sound and light detection circuit, the buzzer produces continuous sound, and the light-emitting diode flashes to send out a detection signal.
From the principle of the flammable gas detector, it can be seen that if electromagnetic interference occurs, the detected signal will be affected, and data deviation will occur;
If there is a collision or vibration that causes the device to break the circuit, the detection will fail; if the environment is too humid or the device is flooded, it may also cause a short circuit in the flammable gas detector, or a change in the line resistance value, resulting in a detection failure.
