Sensors for detecting CO, CH4, O2, H2S in coal mine handheld explosion-proof four-in-one gas detector
my country is a large coal-producing country in the world, and it is also one of the countries with the most severe situation of coal mine safety production. In the prevention and control of coal mine accidents, CH4, CO2, and CO are the main monitoring objects.
The harmful gas gushing out of coal rocks during the underground mining of coal mines is collectively called gas, and the main components of gas are hydrocarbon compounds such as CO, H2S, and CH4. In recent years, there have been many underground accidents in my country's coal mines, and the number of casualties exceeds half of all major accidents.
Common underground gas disasters mainly have three different types: gas explosion, gas explosion and gas combustion. In order to prevent accidents in coal mines, the detection of underground gas is very important.
In industrial sites, gas explosions in coal mines and employee gas poisoning accidents occur from time to time, and almost all of them happen when people are unprepared, which not only seriously threatens the safe production of various industrial sites such as petrochemical, coal mine and metallurgy, but also caused social panic.
Risks in chemical and coal mining industries mainly come from the production of toxic and harmful gases, or the leakage of industrial gases, including: carbon monoxide, carbon dioxide, methane, hydrogen sulfide, etc., as well as hypoxia and suffocation.
Among them, methane is the most harmful gas to the safety of factory facilities and personnel. Because methane is colorless, odorless, and easy to burn, its concentration often exceeds the standard without knowing it, putting workers in danger. Once a small number of fire sources appear, or even just Static sparks will directly lead to explosions. The mine-used handheld explosion-proof four-in-one gas detector is a safety detection device designed for workers to detect on-site methane concentration and discover risks in time.
In coal mine accidents, gas explosions and fires caused by gas combustion account for a large proportion, and the two often occur together. The primary cause of gas explosions is the mobilization of gas in mines. The main component of gas is methane (CH4), accounting for about 83-89%. It is a gas formed and stored in coal seams during the coal formation process. most dangerous gas.
Methane gas is colorless, tasteless, odorless, and its density is 0.7164kg/m3. When the mixture reaches a certain concentration, it will cause combustion or explosion when it encounters a high-temperature fire source. Calculated by volume, methane is explosive when the concentration is 5.3-15.0%. The accumulation of methane gas in the mine has become a serious problem that plagues the safe production of coal mines.
In my country's coal mine safety accidents, the casualties caused by gas explosions account for more than 50% of the casualties in all serious accidents, causing great harm to the national economy and the lives of citizens.
In addition, carbon monoxide poisoning is also one of the most frequent accidents in petrochemical plants. When the concentration reaches a certain level in a confined space, sparks will cause explosions, posing a serious threat to the safety of workers, especially the leakage and diffusion of industrial gas. , is the biggest safety hazard for the surrounding residents. Therefore, the detection of carbon monoxide gas leakage and the control of its concentration are the best solutions to avoid poisoning and blasting accidents.
A large amount of carbon monoxide will be produced in coal mine fires or gas and coal dust explosion accidents. And in coal mines, CO is also one of the main gases that cause gas explosions. It can be seen that both the cause of the gas explosion and the products after the gas explosion are related to CO.
CO is a colorless, tasteless, odorless, highly toxic gas with a specific gravity of 0.967, almost insoluble in water, and is inactive under normal conditions. Can explode in case of fire. CO is a highly toxic gas. When inhaled by the human body, it will cause tissue hypoxia, inhibit tissue breathing, and endanger people's health and safety.
"Coal Mine Safety Regulations" stipulates that in the ambient air of coal mines, the maximum allowable concentration of CO is 0.0024%. In addition, coal produces CO during the low-temperature oxidation stage, and the CO outflow changes steadily, which can objectively reflect the basic law of spontaneous combustion of coal. CO is also a sensitive indicator for predicting mine fires in the early stage.
The four-in-one gas detector can continuously detect the concentration of 4 gases including CH4, O2, CO, and H2S together, and can give an alarm if it exceeds the limit. The detector uses an 8-bit micro-manipulator as the control unit, and uses high-precision detection components with high sensitivity. , The response speed is fast, the screen adopts liquid crystal with wide temperature range, and the display is clear and reliable. When it is detected in the environment that the concentration of the gas to be measured reaches (or exceeds or falls below) the preset alarm value, the detector will immediately generate sound and light alarms.
The sensor for detecting CH4, O2, CO, H2S in the four-in-one gas detector, the technical engineer of Gongcai.com recommends CH4 sensor TGS6814-D01, O2 sensor O2-M2, CO sensor CO-AM, CO sensor TGS5141, H2S sensor H2S- A1.
The conventional four-in-one gas detection and alarm instrument detects four gases: hydrogen sulfide H2S, carbon monoxide CO, oxygen O2, and combustible gas Ex.
In a broad sense, a four-in-one gas detector is an instrument that can detect any four different gas concentration values at the same time, not necessarily a combination of four conventional gases such as combustible gas, oxygen, carbon monoxide, and hydrogen sulfide, just look at the literal meaning , should be all four different gases in any combination.
In a narrow sense, the understanding of the four-in-one gas detector is only for the detection of the concentration of the four conventional gases O2, H2S, CO, and Ex, rather than including all four in a broad sense. Combination of gases.
Whether it is a four-in-one gas alarm in a broad sense or a conventional four-in-one gas alarm in a narrow sense, in fact, in terms of types, it can be mainly divided into two types: fixed online type equipment and portable handheld type equipment. Great variety. The former is mainly used for continuous real-time online monitoring of the leakage of the four gases in a fixed location, while the latter is used for temporary detection or short-term measurement of the concentration of the four gases in the ambient air of a certain area.
From a professional point of view, which gases the four-in-one gas detector can detect depends mainly on the gas detection sensor built into the instrument. Since most of the four-in-one gas alarms produced by most manufacturers adopt standard modular design, gas sensors can be plug-and-play. Therefore, in fact, for the gas detected by the four-in-one gas detector, as long as the corresponding gas sensor is built in advance, and the calibration and software settings are performed, the corresponding gas concentration can be detected. To learn more about the selection of gas sensors in the four-in-one gas detector, please consult the online technical engineer of Gongcai.com.
