The principle of the detection part of the combustible gas detector is that the instrument's sensor uses a detection element, a fixed resistor and a zero-point adjustment potentiometer to form a detection bridge.
The bridge uses platinum wire as the supported catalyst 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 combustible gas and diffuses to the detection element, there will be flameless combustion due to the catalysis effect, so as the temperature of the detection element increases, the resistance of the platinum wire increases, causing the bridge to lose balance, so that a voltage signal is output and the Size of this voltage proportional zThe concentration of the combustible substance is gas. Concentration of aggressive gases.
The principle of the detection part is that when the concentration of the measured combustible gas exceeds the limit value, the amplified bridge output voltage and the circuit detection voltage through the voltage comparator a square wave is generated. The device outputs a series of square wave signals to control the sound and light detection circuitry. The buzzer will emit a continuous tone and the LED will flash to emit a detection signal.
When using the combustible gas detector, we should pay attention to the following points:
1) In order to use the combustible gas detector, we need to find him first analyze the leak location of the device. Analyze the direction of leakage, pressure and other factors, at the same time draw the distribution map of their probe positions and divide accordinglynd in three classes I, II and III a the severity of the leakage.
(2) According to the density of the leaked gas and in combination with the air flow trend, a three-dimensional flow trend diagram of the leak is synthesized and an initial set point scheme is made at the downstream position of the flow.
(3) Using specific factors such as the wind direction and the airflow direction of the site, judge the direction of leakage of the combustible gas in the case of a large amount of leakage.
(4) Investigate whether the leak state of the leak location is micro-leak or jet. If it is a micro leak, the setpoint position should be closer to the leak point. If it splashes, move away from the leak. The final setpoint plan is created taking these conditions into account. In this way, it is possible to estimate the quantity and type that needs to be purchased.
(5) To OIn places with hydrogen leaks, the detector should be installed at the level above the leak.
(6) If there is a possibility of a large amount of flammable gas leaking from a place, a detection point should be set up at a distance of 10-20m in accordance with the relevant regulations. In the case of small pump rooms with discontinuous operation, attention must be paid to the possibility of escaping flammable gases and a detector must be installed at the leeward outlet.
(7) In the open environment where flammable gas diffuses and escapes, in the absence of good ventilation conditions, it is easy to bring the flammable gas content in the air to a certain level Part approaches or reaches lower explosive limit. The concentration cannot be ignored.
(8) When using a combustible gas detectorFor media with a gas density greater than air, the detector should be on levelne be installed below the leak point while at the same time paying attention to the properties of the environment. Particular attention should be paid to the establishment of safety monitoring points in places where flammable gases can accumulate.
From the principle of the combustible gas detector, it is understood that when there is electromagnetic interference, the detection signal will be affected and there will be data deviation; if there is a collision or the environment is too humid or the device enters the water, there may also be a short circuit in the combustible gas detector and a change in the line resistance value, leading to detection error.