Introduction to the working principle of the combustible gas detector
A combustible gas detector is a detector installed and used in industrial and civil buildings to respond to single or multiple combustible gas concentrations.
There are two types of combustible gas detectors that are often used in daily use: catalytic combustible gas detectors and semiconductor combustible gas detectors.
Restaurants, hotels, family workshops and other places that use gas, natural gas, liquefied gas mainly use semiconductor-type combustible gas detectors, and industrial places that emit combustible gas and combustible gas mainly use catalytic combustible gas detectors.
The semiconductor combustible gas detector uses the change of the surface resistance of the semiconductor to determine the concentration of combustible gas.
The semiconductor combustible gas detector adopts gas-sensitive semiconductor components with higher sensitivity. When it encounters a flammable gas while it is working, the resistance of the semiconductor drops by a value corresponding to the concentration of the flammable gas.
The combustible gas detector consists of two parts: detection and detection, with detection and detection functions.
The principle of the detection part of the combustible gas detector is that the sensor of the instrument uses a detection element, a fixed resistance and a zero-adjusting potentiometer to form a detection bridge.
The bridge circuit uses platinum wire as the carrier catalytic element. After energization, the platinum wire temperature rises to the operating temperature, and the air reaches the surface of the element by natural diffusion or other means.
When there is no flammable gas in the air, the output of the bridge circuit is zero. When the combustible gas contained in the air diffuses into the detection element, flameless combustion occurs due to the catalytic action, the temperature of the detection element increases, the resistance of the platinum wire increases, and the bridge circuit is unbalanced;
There is a voltage signal output, the magnitude of the voltage is proportional to the concentration of the combustible gas, the signal is amplified, the analog-to-digital conversion is performed, and the concentration of the combustible gas is displayed on the liquid crystal display.
The principle of the detection part is to amplify the output voltage of the bridge and the circuit to detect the set voltage when the concentration of the combustible gas to be measured exceeds the limit value;
The square wave generator outputs a group of square wave signals through the voltage comparator to control the sound and light detection circuit, the buzzer emits continuous sound, the light-emitting diode flashes, and the detection signal is issued.
From the principle of the combustible gas detector, it can be seen that if electromagnetic interference occurs, the detected signal will be affected, and data deviation will occur;
If the equipment is damaged due to collision or vibration, the test will fail; if the environment is too humid or the equipment is flooded, it may also cause a short circuit of the combustible gas detector, or the line resistance changes, and the test fails.
