Combustible gas detector use and maintenance
1. 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 flammable gas detectors that are used most frequently in daily life: catalytic flammable gas detectors and semiconductor flammable 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.
2. The catalytic combustible gas detector uses the resistance change of the refractory metal platinum wire to measure the combustible gas concentration. 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.
3. 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.
4. 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. , 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. The principle of the detection part is that when the concentration of the measured flammable gas 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, control sound, In the 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 there is electromagnetic interference, the detection signal will be affected, and data deviation will occur; if there is a collision or vibration that causes the equipment to break, the detection will fail; if the environment is too humid or the equipment enters water, it may also be damaged. Cause a short circuit in the flammable gas detector, or a change in the line resistance value, resulting in a detection failure.
