I. Fire and its Harm Fire refers to the disaster caused by burning out of control in time or space. The so-called combustion is an exothermic reaction between combustible and oxidant, which is usually accompanied by flame, luminescence and smoke. Combustion must have three conditions: combustible, combustion-supporting material and ignition source, all of which are indispensable. Sometimes, in a certain range, although all three conditions exist, because there is no combination and no interaction, there will be no burning phenomenon. If any condition of combustion is cut off, the fire will go out. Fire safety is not everything, but there is nothing without safety. The majority of graduate students must fully understand the fire and its harmfulness, improve their awareness of safety precautions, earnestly strengthen the study of fire protection knowledge, and improve their self-prevention and self-help ability. Only in this way can we effectively prevent and reduce fire hazards and create a safe learning and living environment. Second, the development law of fires People have proved in practice that most fires are from small to large, from weak to strong, and gradually become fires. The formation process of fire is generally divided into four stages: initial stage, growth stage, violence stage and decline stage, among which the first three stages are the key to fire hazards. (a) the initial stage of the fire. Generally, when solid combustible materials burn, the fire source area is not large, the flame is not high, the flue gas velocity is not fast, the radiation heat is not strong, and the fire develops slowly around. The length of this period varies with the structure and space of the building. In this case, only a small amount of manpower and simple fire extinguishing tools are needed to put out the fire. (2) Fire growth stage. If the fire in the initial stage is not found or extinguished, with the extension of combustion time, the combustion intensity increases, the temperature rises gradually, the combustion area is gradually filled with smoke, and the surrounding combustible materials are heated rapidly. At this time, the gas convection is enhanced, the combustion speed is accelerated, and the combustion area is rapidly expanded, which will form a big flame in an instant. In this case, it is necessary to have certain manpower and fire-fighting equipment to put out the fire in time and effectively. (? Three? )? The intense stage of the fire. With the extension of combustion time, the combustion speed is accelerated, the combustion area is rapidly expanded, the combustion temperature rises sharply, and the continuous temperature reaches? 600? Degree arrived? 800? The radiation heat is the strongest, the gas convection reaches the highest speed, and the heat release and combustion products of combustion substances reach the highest value. At this time, building materials and structures are damaged, deformed or collapsed. The length and temperature of this period depend on the fire resistance rating of the building. In this case, it is necessary to organize more fire fighting forces and spend a long time to control and put out the fire. (? Four? )? Fire fading stage. After intense combustion, the fire decreased, the indoor temperature decreased, the smoke dissipated, and the fire gradually subsided. ? Third, the causes of college fires (? One? )? Careless use of an open flame can cause a fire. For example, lighting candles, lighting mosquito-repellent incense, smoking, using liquefied gas and burning garbage. (? Two? )? Electrical fire. For example, illegal use of electricity and improper use of electrical appliances. ? (? Three? )? Violation of laboratory operating procedures. ? Fourth, how to prevent fires The key to preventing fires is to do a good job in fire prevention. Teachers and students should conscientiously implement fire laws and regulations, consciously abide by fire safety management regulations, and prevent fires.