The causes of gas accidents are: (1) lack of gas safety knowledge, such as not wearing a gas mask to rescue after an accident, which leads to the expansion of the accident, or not wearing a gas mask when working in a gas-filled area. (2) Gas equipment leaks gas. (3) There are hidden dangers in the equipment, the effective height of the water seal is not enough, the height of the radiation pipe is not enough, and the gas treatment explosion-proof fan. (4) The gas treatment is not thorough, and the gas source is not firmly cut off. If the blind plate is not blocked, the air supply can only be cut off through the blinds. (5) The superior substation or automatic control electrical equipment has an accident and suddenly loses power. (6) Unskilled operation technology, misoperation, or ignorance of operation technology. (7) After gas treatment, tar, naphthalene and other deposits in gas equipment spontaneously ignite or explode in case of fire. (8) The blind plate has no grounding wire, the steam pipeline at the job site is not insulated (or the insulation layer falls off), and the blind plate and spreader rub against the pipeline. 2. Gas poisoning and its prevention. The gas contains a lot of toxic gases, such as carbon monoxide, hydrogen sulfide, benzene, phenol and ammonia. Blast furnace gas and producer gas contain a lot of carbon monoxide. After being inhaled into human body, carbon monoxide combines with heme in blood, which makes blood lose its oxygen transmission ability and causes central nervous system disorder. Mild people have headache, dizziness, tinnitus, nausea and vomiting, while severe people don't listen to instructions, will disorder, foaming at the mouth, incontinence and so on. Severe coma or even death. Natural gas contains a lot of methane, which is non-toxic, but when the content is high, the oxygen content is relatively reduced. When the methane content in the air reaches more than 10%, the reaction of human body is weakness, dizziness, and then loss of consciousness until death. In order to prevent gas poisoning, we must strictly abide by the relevant provisions of the gas safety regulations. First of all: (1) Check the tightness of gas equipment frequently to prevent gas leakage. Alarm devices should be set at the parts where gas equipment is easy to leak. If leakage is found, it should be handled in time. If you find the equipment emitting gas or working with gas, you should wear a gas mask. (2) The newly-built or overhauled equipment shall be tested for strength and leakage, and can be put into production only after passing the test. (3) When working in gas equipment, the carbon monoxide content and allowable working time shall comply with the provisions in Table 26.3. Table 26.3 CO content and allowable working hours CO content mg/m3 Continuous working hours 30 National Health Work Standard 50 shall not exceed 1 hour 100, and half an hour 200 shall not exceed 15 ~ 20 minutes (4) The gas source shall be cut off reliably, such as blocking the blind plate and setting water seal. The blind plate should be tested, and the water seal valve cannot be used as a separate cut-off device. The water seal in the gas system should be kept at a certain height, and overflow should be kept frequently in production. The effective height of water seal C is calculated as 1000mm water column indoors and 500mm water column outdoors. (5) When cleaning and repairing gas equipment, the residual gas must be treated and can only be carried out after passing the test. For workplaces in gas areas, the content of carbon monoxide in the air should be analyzed frequently, and if it exceeds the hygienic standard stipulated by the state, the reasons should be checked and analyzed and handled. (6) The gas area should be marked with "gas danger area". When a gas poisoning accident occurs, it shall immediately notify the gas rescue station for rescue and treatment. 3. Gas fire, explosion and its prevention. Gas is a combustible gas. When the gas is mixed with air, the combustible gas in the gas reacts strongly with oxygen in the air, from slow oxidation to ignition temperature, from slow oxidation to instantaneous violent oxidation, that is, it reaches the explosion stage. If a gas fire occurs in a closed container, it will cause a severe explosion accident and be very destructive because of its rapid combustion and sudden expansion. Measures to prevent gas from igniting and exploding: (1) Prevent gas and air from mixing into explosion proportion, control the oxygen content not to reach the explosion limit, and prevent fire sources, sparks or hot objects from contacting with it. Gas pipelines and gas pipelines must have reliable cutting devices, and it is not allowed to cut off only by valves. When the blast furnace gas pipeline is driven, it is necessary to open the radiation pipe at one end and the manhole at the other end, and use the blower for forced ventilation. The coke oven gas pipeline needs to be removed by steam, or steam is introduced first and then ventilated by blower. (2) When the gas discharge is stopped, no open flame is allowed within 40 meters around the discharge pipe. After the gas pipeline equipment is stopped, it must be handled immediately according to the specified requirements, and hot work can be carried out only after it is qualified. Blast furnace gas and producer gas can be detected by pigeons or other detection and alarm devices, and coke oven gas and natural gas can be detected by explosion test or carbon monoxide content analysis. (3) When hot work is carried out on the gas pipeline, the positive pressure in the pipeline must be kept not less than 50 mm water column. When the pressure is less than 50 mm water column, the power supply of the welding machine should be cut off immediately. (4) When using gas, it must be ignited under normal pressure. When igniting, gas must be supplied after ignition, and the flue door and oven door should be opened. (5) In case of gas explosion accident, immediately notify the user to stop fire fighting, cut off the gas source, close the valve or water seal, and block the blind flange. Use steam or natural ventilation to treat the residual gas to prevent it from exploding again. When the gas pipeline catches fire locally, the fire site can be blocked with yellow mud. If the cracks are too big to be blocked with yellow mud, emergency measures should be taken to inform the relevant units to stop using gas, and then fire fighting and treatment measures should be taken. Recommended gas detection equipment: