Treatment and self-help in case of fire

Learning to use fire is an important symbol of entering the civilized world. The following is the basic knowledge of fire protection that I have compiled. Welcome to reading.

Basic knowledge of fire-classification of fire

According to the national standard GB4968-86 "Fire Classification", fires are divided into four categories: A, B, C and D.

1, Class A fire refers to solid material fire. This kind of substance often has the nature of organic matter, and it can produce glowing embers when burning. Such as wood. Cotton, wool, hemp, paper and other types of fires.

2. Class B fire refers to liquid fire and fusible solid matter fire extinguishing. Such as gasoline, kerosene, crude oil, methanol, ether, aldehyde, ketone and other water-soluble liquids and meltable asphalt, paraffin, natural oil and other fires.

3. Class C fire refers to gas fires such as gas, natural gas, methane, ethane, propane, hydrogen fire and liquefied petroleum gas fire.

4. Class D fire refers to metal fire: such as potassium, sodium, magnesium, titanium, lithium, zirconium, aluminum-magnesium alloy and other fires.

In addition, there are electrical fires, which refer to fires in which charged objects burn.

Second, the characteristics of the fire

1. There are many factors of fire. Modern buildings have complex functions, frequent people flow, inconvenient management, and fire hazards are difficult to find; Indoor decoration requires high requirements and there are many flammable items; At the same time, there are many fire sources, such as the torch fire in the kitchen and maintenance pipelines and equipment, the afterglow of cigarette butts, improper use of various electrical equipment, etc., which can all cause fires. 1985 Harbin White Swan Hotel, a foreign guest's cigarette butt caught fire on the carpet, causing a fire. The foreign guest was approved and published in the newspaper at that time. A single spark ignited a forest fire; A missile attacked China's embassy in Yugoslavia, and a plane leveled American skyscrapers.

2. The higher the building, the stronger the wind. There are many vertical passages in high-rise buildings, such as elevator shafts, pipeline shafts, ventilation shafts, cable shafts, garbage slides, escalators and stairwells. Due to air convection, the horizontal diffusion velocity of smoke in fire is 0.5 ~ 0.8 m/s, while the vertical velocity can reach 3 ~ 4 m/s, which rises by 65438+ in half a minute. With the supplement of fresh air, the fire spread faster. For example, a plumber in Shenyang was repairing welded pipes in the bathroom at that time, which caused a fire, and the fire rose to the top of the building along the pipes. Therefore, high-rise buildings should be provided with refuge floors and the top floors should be leveled so that helicopters can stop for fire rescue.

3. It is difficult to evacuate and it is easy to cause casualties. Stairs are the main passage for evacuation, so it is difficult to evacuate when there are many people. Moreover, the smoke spreads quickly and contains harmful gases such as carbon monoxide, which will suffocate and faint in the smoke, causing heavy casualties and increasing the difficulty of fire fighting. Therefore, public buildings and corridor-style residential buildings need at least two safety exits or safety stairs.

4. Difficulties in the battle. At present, due to the limited capacity of fire-fighting equipment in China, it is difficult to put out fires from the outside in buildings over 24 meters. With the help of city fire engines, multi-storey buildings can be put out. The main building of a high-rise building is in the center, surrounded by a podium. Fire engines can't get close to high-rise buildings, and they also need to work in an environment with strong thermal radiation and dense smoke, which increases the difficulty of fire fighting and extinguishing. Therefore, high-rise buildings should give priority to self-rescue, and fire exits must be set around high-rise buildings. Example: 197 1 Seoul 22nd floor cafe, an oil refinery exploded next to it, causing the cafe to catch fire. There is a self-help fire extinguishing system in the cafe, but there is no complete alarm device. The water pump didn't start in time, and the sprinkler system didn't work. At that time, 40 fire engines were dispatched and 500 firefighters put out the fire. The fire burned for 6 hours and 1 168 died.

Three? Basic conditions of fire combustion

Fire is combustion, and combustion is a chemical reflection of exothermic luminescence. Where combustion occurs, there must be both necessary and sufficient conditions for combustion.

1. There are three necessary conditions for combustion, namely combustion, combustion-supporting and temperature.

1) Combustible Any substance that can react violently with oxygen or other oxidants in the air can be called combustible. There are many kinds of combustible materials, which can be divided into gas combustible materials, liquid combustible materials and solid combustible materials according to their physical states. Such as wood, paper, gasoline, acetylene, metal sodium, potassium and so on.

2) Oxidant (oxygen promoter) Any substance that can help and support combustion, that is, the substance that can undergo oxidation reaction with combustible substances, is called combustion-supporting substance. Such as air, oxygen, chlorine, potassium bromochlorate, potassium permanganate, sodium peroxide, etc.

3) Temperature (ignition source) Ignition source refers to the energy that supplies combustible substances to react with oxygen or combustion improver. The most common are naked flame, red hot body, Mars and electric spark.

The so-called open flame. Open flame is the most common and intense ignition source, such as matches and cigarette butts will cause fires; The temperature of an open flame is about 700? Between 2000 and 2000, any combustible substance can be ignited.

The so-called red-hot body. Refers to an object with high temperature due to heat storage under the action of high temperature or current factors. Such as red-hot iron and metal equipment. The speed at which a red-hot object ignites a combustible substance mainly depends on the nature and state of the substance.

When iron and iron or iron and stone collide strongly, Mars will produce sparks. Although the energy of Mars is small, its temperature is very high, about 1200℃, and it can also ignite flammable solid substances such as cotton, cloth, hay and chaff.

Arc and electric spark are sparks released by discharge between two poles or arc produced by breakdown, which can cause flammable gas, liquid vapor and solid substances to catch fire, and are relatively dangerous ignition sources.

2. Sufficient conditions for combustion include: in some cases, although the three necessary conditions for combustion are met, combustion may not necessarily occur. This requires the concentration of combustible materials (when the content of H2 in the air reaches 4% ~ 75%, it will ignite or even explode) and provide sufficient oxygen, otherwise the combustion will not continue. The table below shows the minimum oxygen content for burning certain substances.

Basic measures of fire prevention

According to the basic conditions of combustion, all fire prevention measures are to prevent the three conditions of combustion from combining at the same time, so fire prevention measures are considered from these aspects.

1, control combustible materials to replace flammable combustible materials with flame retardant or incombustible materials; Replace wood structure with cement or concrete structure; Replacing combustible materials with fire retardant coatings to improve the fire resistance limit; Strengthen ventilation in places where combustible gas or steam is emitted to prevent the accumulation and formation of explosive mixtures; Close the angle valve on the container containing flammable gas or combustible gas to prevent leakage.

2. Isolation of combustion-supporting materials The production equipment used to produce explosive chemicals should be sealed to prevent contact with air to form flammable mixtures; For example: ① Stored in a chemical warehouse that is flammable and explosive in contact with water, and water is strictly prohibited (because the reaction K+H2O=KOH+H2? ), once the fire is on fire, dry sand or dry powder should be used to extinguish the fire or buried, so that the combustible material is cut off and suffocated by oxygen, and it is forbidden to extinguish the fire with water or foam; (2) In the warehouse of oil refinery, foam fire extinguishing system is often used to isolate the air to prevent cooling explosion.

Eliminating the fire source is the first sign of fire, so we will nip it in the bud. No fire source is allowed in warehouses, oil depots and gas stations, and integral explosion-proof electrical equipment is installed in explosive dangerous places.

4. Prevent the fire from spreading In order to prevent the fire from spreading, fire exits, firewalls and fire safety doors should be set between building partitions. Fire? Spacing; Divide fire zones in a large area, separate them with shutter doors, and install flame arresters on combustible gas pipelines; Plastic pipes are flammable, and once they catch fire, the flame from the lower layer will spread to the upper layer along the pipes, so a fire stop ring is set on the pipes under the floor.

Five basic principles of fire fighting

The basic principle of fire fighting can be divided into four aspects: cooling, suffocation, isolation and chemical inhibition. The first three kinds of fire extinguishing actions belong to physical processes; Chemical inhibition is a chemical process.

1, the ignition point of cooling fire extinguishing is the condition of continuous combustion of combustible materials, so for general combustible solids, cool to below the ignition point; For flammable liquids, when they cool below the flash point, the combustion reaction will stop. Water is used to put out fires of general solid substances, mainly through cooling. Water can absorb a lot of heat and change from liquid to gas, which makes the temperature of combustion products drop rapidly, so water is the main fire extinguishing agent, which is economical and affordable. There are not many side effects. For flammable liquids, water cannot be used to extinguish the fire, and foam is usually used to extinguish the fire.

2. Asphyxiating fire depends on oxygen, as long as the concentration of oxygen in the surrounding air? 15% may burn, so reducing the oxygen concentration can put out the fire, such as closing the holes with wet quilts and wet canvas, closing doors and windows to prevent fresh air from entering, or suffocating the fire with portable CO2 or pipeline fire extinguishers.

3. Isolation and fire extinguishing will isolate combustible materials from flame and oxygen, and the combustion reaction will automatically terminate; Such as transferring combustible materials, closing relevant valves and cutting off the passage of combustible gas and combustible liquid. In addition, fire extinguishers are used to isolate fuel from oxygen and heat. Generally, foam extinguisher is used to cover the surface of combustion body or solid with foam to separate combustible materials from flame and air. Seal doors and windows to prevent flame and hot air from spreading through the holes.

4. Chemical suppression fire extinguishing produces substances that inhibit combustion through chemical reactions. The combustion of combustible materials is a chain reaction of free radicals. Hydrocarbons are activated in the combustion process to produce a chain reaction of free radicals H, OH and O. Halogenated fire extinguishing agents can effectively inhibit the generation of free radicals, interrupt the combustion reaction or reduce free radicals, and achieve the purpose of fire extinguishing. However, halogenated fire extinguishing agents will destroy the atmospheric ozone layer. Therefore, halogenated extinguishing agents should be used as little as possible. Dry powder fire extinguishing agent also belongs to chemical suppression fire extinguishing, and the fire extinguishing effect is very good. Halogenated fire extinguishing agent can extinguish equipment, so can dry powder fire extinguishing agent, but dry powder fire extinguishing agent is easy to pollute the environment and destroy equipment. Therefore, dry powder extinguishing agent should not be used in precision instruments.

Several ways of heat transfer

The process of fire is accompanied by the process of heat transfer, and there are three ways of heat transfer, namely heat conduction, heat convection and heat radiation.

1, the process of heat transfer from high temperature to low temperature through substances in direct contact is called heat transfer. The main factors affecting heat conduction are temperature difference, thermal conductivity, thickness and cross-sectional area of heat-conducting objects. Solid matter is a strong thermal conductor, followed by liquid and gas.

2. Thermal Convection The phenomenon that heat is transferred from one place to another in space through a flowing medium is called thermal convection. The direction of thermal convection is that hot fluid flows upward and cold fluid flows downward. So the flame always spreads upward and burns. The main factors affecting thermal convection are temperature difference, area and height of ventilation holes and height of ventilation holes. Thermal convection is the main way of heat transfer. It is the most important factor affecting the development of early fire. For example, the greater the temperature difference, the faster the thermal convection, and the larger the area of ventilation holes, the faster the thermal convection.

3. The phenomenon that thermal radiation transfers heat in the form of electromagnetic waves is called thermal radiation. The main feature of thermal radiation is that any substance (solid, liquid, gas) can radiate heat in the form of electromagnetic waves, and can also absorb the heat radiated by other substances. At the same time, thermal radiation does not need any medium, and can also be radiated through vacuum. The heat of thermal radiation is proportional to the fourth power of flame temperature. Therefore, when combustion is in the development stage, thermal radiation becomes the main form of heat transfer.

Prevention of Fire Accidents In order to prevent fire accidents and ensure the fire safety of schools, students should conscientiously study and consciously abide by the Fire Protection Law of People's Republic of China (PRC), fire protection laws and regulations formulated by governments at all levels and public security fire departments, and various safety management regulations of schools. In classrooms, laboratories, research rooms and workshops, the above safety management regulations, operating procedures and various systems shall be strictly observed. When using equipment and instruments, carefully check whether the power supply, pipeline, fire source and auxiliary instruments and equipment are abnormal, whether they are properly placed and whether the operation and use process is clear. Only after all the preparatory work is completed can we carry out experiments or other operations. For experiments or internships involving the use of flammable and explosive dangerous goods, more attention should be paid to fire safety, and indoor air circulation must be maintained to prevent the gas emitted by flammable and explosive substances from reaching explosive concentration in the air. The experimental practice place should be equipped with sufficient fire-fighting equipment, and be familiar with its placement and use. When leaving the experimental practice site, the power supply, fire source, gas source and water source should be turned off. According to the system requirements, clean up sundries and garbage, and put away all the items. The passage of the experimental practice place should be kept clear, and articles should not be piled up in the doorway, corridor, aisle and other passages.

In the dormitory, students should strictly abide by the dormitory safety management regulations and do not pull wires indiscriminately; Do not use high-power appliances such as electric stoves and rice cookers; Do not add circuit fuses at will; Open flame lighting shall not be used in the dormitory; Do not bring inflammable and explosive dangerous goods into the dormitory; If unsafe phenomena are found, they should be reported to managers or relevant departments in time and eliminated as soon as possible; Take good care of the fire-fighting facilities and equipment in the dormitory. Don't move or use it for other purposes at will, and master the correct use of fire fighting equipment. Non-fire facilities must be approved by the school security department. When there is no one in the room, turn off the electrical appliances and power switch; It is forbidden to burn things in the dormitory.

Treatment and self-help in case of fire. In case of fire, alarm and fire extinguishing should be carried out simultaneously. When there is only one person in the fire scene, you should call for help and put out the fire. If the fire is in the early stage and the burning area is small, you are sure to put it out, and you should take the fastest and most effective way to put it out immediately. Because if you don't put out the fire at this time, but call the police, it will turn a small fire into a big fire because of the delay of time, forming a fire that is difficult to put out. If you find a fire, the fire is so strong that it is difficult for you to put it out, you should call the police immediately. What is the alarm number of the public security fire department? 1 19? When calling the police, you should calmly, clearly and briefly explain the fire location (residential street, unit, building name, etc.). ), burning substances, fire situation, etc. At the same time, you should tell the alarm desk your name and contact number so that you can contact at any time. After the alarm is completed, people should be sent to wait at the school gate or street intersection to guide the fire truck to quickly reach the fire scene to extinguish the fire. Looking for fire at school, besides fighting? 1 19? In addition to the alarm call, you should also report to the duty room of the school security office (if there is a fire in the school, you can also report directly to the duty room of the security office).

Pay attention to cut off the power supply and gas source that causes the fire; When putting out the fire, inflammable and explosive dangerous goods near the fire site should be transferred, and those that cannot be transferred should try to cool down.

When there is a fire, if you are trapped by the fire, keep your head calm and don't panic. Choose the best self-help plan according to the fire, buy time and get out of the danger zone. There are several ways to save yourself:

1. Don't waste precious escape time on dressing and finding money after the fire. Quickly choose the channel opposite the fire source to get out of danger. When escaping from the fire, if you encounter smoke, you should try to lower your body or crawl, and never walk upright to avoid being suffocated by smoke. The clothes are on fire. Don't panic. Roll on the ground quickly to put out the fire.

2. If the stairs are on fire, but the fire is not very fierce, you can put on clothes or soak the sheets in the water and rush down the stairs. If the fire at the stairway is fierce, you can use a rope or tear the sheets into strips to connect them, hang one end on a solid door, window or other heavy object, and then slide down along the rope or cloth. Don't escape from the fire by elevator. Prevent the elevator circuit from being damaged by fire and trapped in the elevator.

3. If all escape routes are cut off, you should retreat indoors and take smoke prevention and fire prevention measures. Close the doors and windows, sprinkle water to delay the spread of the fire, and cover your nose and mouth with multiple layers of wet towels for personal protection. At the same time, throw small things outdoors, and you can send out a distress signal with a flashlight at night. However, if the fireworks are a serious threat and life-threatening, and the floor is only two or three stories, when you are forced to jump off a building, you can first throw some soft items such as quilts on the ground, and then slide down the window sill with your hands, which can minimize the jumping height, ensure that your feet land first, and reduce craniocerebral injury and visceral injury.

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