Ten dangerous chemicals fire fighting countermeasures

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Hazardous chemicals are prone to fires and explosions. Different kinds of chemicals and fires in different situations have different methods of fighting. If they are not properly disposed, they will not be able to save them effectively, but will further expand the disaster. In addition, since the chemicals themselves and their combustion products are mostly highly toxic and corrosive, they are highly susceptible to poisoning and burns. Therefore, fighting a dangerous chemical fire accident is an extremely important and very dangerous job.

In the actual work, the personnel engaged in the production, use, storage and transportation of chemicals should be familiar with and master the main dangerous characteristics of the chemicals. In the event of a fire, each employee should clearly understand their roles and responsibilities and be proficient in the fire. The corresponding rescue measures are very necessary.

In general, when fighting a chemical fire, the following points should be noted first:

★ Firefighters should not act alone;

★The entrance and exit of the accident site should always be kept clean and smooth;

★ Choose the right fire extinguishing agent and suitable fire extinguishing equipment;

★ Always consider the safety of personnel when extinguishing fires.

Fighting dangerous chemical fires must not be done blindly. The right fire extinguishing agent and appropriate fire extinguishing equipment should be selected for each type of chemical to safely control the fire. The fight against chemical fires must be carried out by a professional fire brigade. Other personnel should not act blindly. After the arrival of the professional fire brigade, they should cooperate with the rescue.

First, the general requirements for the fire of dangerous chemicals

Personnel engaged in the production, operation, storage, transportation, loading and unloading, packaging and use of hazardous chemicals, as well as personnel handling hazardous chemicals and fire-fighting and ambulance personnel, should be familiar with and master the main hazard characteristics of such articles and their corresponding fire-extinguishing method. Only by knowing yourself and knowing what to do before you can win in the fire of various dangerous chemicals. The general requirements for the fight against hazardous chemical fires are:

1. Control first, then destroy. In view of the characteristics of the fire spread and large burning area of ​​dangerous chemical fires, we will actively adopt unified command, fast system, block fire to prevent spread, focus on breakthroughs, eliminate dangerous situations, and divide firefighting tactics.

2. The rescue personnel should occupy the upper or crosswind position to avoid being poisoned by toxic and harmful gases.

3. Fire reconnaissance, fire fighting and fire evacuation personnel should take targeted self-protection measures, such as wearing protective masks and wearing special protective clothing.

4. The main areas of the burning range, the names of the burning articles and their surrounding items, the main dangerous characteristics, and the spread of the fire should be quickly identified.

5. Properly choose the most suitable fire extinguishing agent and fire extinguishing method. When the fire is large, the fire spread should be blocked first, the combustion range should be controlled, and then the fire extinguishing force should be gradually extinguished.

6. For cases where there is a possibility of explosion, rupture, splashing, etc., the need for emergency evacuation should be promptly withdrawn according to the unified evacuation signal and evacuation method (the evacuation signal should be particularly eye-catching, so that all personnel on the site can see or hear it. And often pre-drilled).

7. After the fire is extinguished, the fire-fighting unit shall protect the site, accept the accident investigation, assist the public security fire control department and the safety supervision and management department to investigate the cause of the fire, verify the fire damage, and identify the fire responsibility, without the public security supervision department and the safety supervision and administration department. The consent must not be used to clean up the scene of the fire.

Second, the basic countermeasures to save the compression or liquefied gas fire

Liquefied gases are typically stored in separate containers or piped. The following basic countermeasures should be taken in the event of a fire:

Fighting gas fires should not be blindly extinguished. In the absence of measures to prevent leaks, it is necessary to maintain stable combustion. Otherwise, the combustible gas leaks out to mix with the air, and the explosion occurs in the event of fire, and the consequences are unimaginable.

First of all, the flammable fires ignited by the fire source should be extinguished, the fire spread path should be cut off, the combustion range should be controlled, and the injured and trapped people should be rescued immediately.

If there is a pressure vessel in the fire or a pressure vessel that is threatened by the flame of radiant heat, the evacuation should be evacuated to a safe place under the cover of the water gun.

If the gas pipeline leaks fire, try to find the gas source valve. Make sure the valve is intact, close the valve and the flame will automatically go out.

When the tank or pipeline leakage valve is invalid, the gas pressure and the size and position of the leak port should be judged according to the fire potential, and the corresponding plugging materials (such as cork stopper, rubber stopper, airbag plug, adhesive, pipe bending tool, etc.) should be prepared. ).

After the plugging work is ready, effective measures can be taken to extinguish the fire. Immediately after the fire is extinguished, the plugging material should be used to stop the leak, and the misted water should be used to dilute and disperse the leaked gas. If the leak is too large, it can't be blocked at all. At this time, measures can be taken to cool the fire container and surrounding containers and combustibles, and control the fire range until the gas burns out and the flame will automatically extinguish.

The on-site commander should pay close attention to various danger signs. Once the situation deteriorates, the commander must make an accurate judgment and issue a retreat order in time.

Third, the basic countermeasures for fighting flammable liquid fires

Flammable liquids are also usually stored in different containers or delivered through pipes. Unlike gases, liquid containers have a seal, and some are open. Generally, it is atmospheric pressure, and only the liquid pressure in the reaction kettle (furnace, pot) and the conveying pipe is high. Flammable liquids have specific gravity and water solubility, which can be solved by water and ordinary foam, as well as dangerous boiling and splashing problems. Therefore, fighting a flammable liquid fire is a very difficult battle. Generally take the following basic countermeasures:

First, cut off the way the fire spreads, cool and evacuate the pressure threatened by the fire and contain closed containers and combustibles to control the combustion range. If there is liquid flow, the embankment (or the oil boom) should be used to intercept or dit the diversion. v In time to understand and master the name, specific gravity, solubility of fire liquid, and whether there is danger of poisoning, corrosion, boiling, splashing, etc., in order to take appropriate fire-fighting and protective measures.

For larger tanks or rogue fires, the area of ​​fire should be accurately judged.

★ Small area (usually less than 50 square meters) liquid fire, generally can be extinguished with misty water. It is generally more effective to extinguish the fire with foam, dry powder, carbon dioxide, halogenated alkane (1211, 1301).

★ Large-area liquid fires must be selected according to their relative density (specific gravity), water solubility and burning area, and choose the right fire extinguishing agent to save. Liquids that are light in weight and insoluble in water (such as gasoline, benzene, etc.) are often ineffective with DC water or misty water. Generally use ordinary protein foam or light water foam to extinguish the fire. Liquids that are heavier than water and insoluble in water can be saved with water when they catch fire. Foam can also be used. Extinguishing with dry powder or alkyl halide depends on the size of the combustion area and the combustion conditions. Water-soluble liquids (such as alcohols, ketones, etc.) can theoretically be diluted with water to save, but in this way the liquid flash point disappears and water must occupy a large proportion in the solution. Therefore, it is generally used to fight against soluble foam.

To save flammable liquid fires that are toxic, corrosive or highly toxic to combustion products, the rescue personnel must carry protective masks and take protective measures.

When extinguishing liquid fires such as crude oil and heavy oil that are at risk of boiling over and splashing, if conditions permit, measures such as boiling water mixing and cooling to prevent boiling and splashing may be used.

In the case of a flammable liquid pipeline or storage tank leaking fire, while the cut-off spread limits the fire to a certain range, the pipeline should be managed to find the inlet and outlet valves and closed. If the inlet and outlet valves of the pipeline are damaged or the tank leaks, the material should be quickly prepared to stop the leaking material, then effectively extinguish the flame on the ground, clear the obstacles for the leak, and finally extinguish the flame of the leak and quickly take measures to stop the leak.

Fourth, the basic countermeasures for the fire of explosives

The explosives can be fired with water, air foam (higher foam), carbon dioxide, dry powder and other extinguishing agents. The best fire extinguishing agent is water. Because water can penetrate into the interior of the explosive, a soft plastic film is formed on the crystallized surface of the explosive, which surrounds the crystal and makes it insensitive. When the explosives are on fire, the first thing is to use a large amount of water for cooling. It is forbidden to cover with sand and not with steam and acid-base foam. When the fire is in the room or in the cabin or in the cabin, the doors, windows, doors and cabins should be quickly opened, and the water should be cooled inward. The doors, windows, doors and hatches should not be closed to extinguish the fire. It is necessary to pay attention to the use of shelters, and the use of walls, low-lying areas, trunks, etc. on the fire can be used to prevent personal injury.

Because some explosives are not only toxic, but also the products of combustion are poisonous, you should pay attention to anti-virus when extinguishing fire: toxic explosives should be worn with insulated oxygen or air breathing apparatus to prevent poisoning.

Explosive items generally have special or temporary storage warehouses. Due to the explosive nature of the internal structure, such items are excited by external factors such as friction, impact, vibration, high temperature, etc., which are prone to explosions and are more dangerous to encounter open flames. In the event of a fire in an explosive article, the following basic countermeasures are generally taken:

Quickly judge and ascertain the possibility and danger of recurring explosions, seize the favorable opportunity after the explosion and before the explosion again, take all possible measures to prevent the occurrence of another explosion.

Never use sand to cover the pressure, so as not to increase the explosive power of explosives.

If there is an evacuation, personal safety does have a reliable guarantee. It should be quickly organized to evacuate the explosives around the fire area in time to form an isolation belt around it.

When smashing explosives, the water flow should be hoisted to prevent the strong water flow from directly impacting the stack, so as to avoid the collapse of the stack and cause another explosion.

Fire-fighting personnel should try to use the shelter on the scene or take a low-level water injection such as horizontal, pay attention to self-protection measures.

When the fire-fighting personnel finds that there is a risk of another explosion, they shall immediately report to the on-site command. Immediately after confirmation by the on-site command, the evacuation order shall be issued immediately.

V. Basic Countermeasures for Fighting Oxidizers and Organic Peroxide Fires

Oxidants and organic peroxides are a miscellaneous from the point of view of fire extinguishing, both solids, liquids and gases. Some oxides are not flammable by themselves, but they can catch fire or explode in the presence of combustibles or acids and bases. Some peroxides (such as dibenzoyl peroxide) can ignite and explode by themselves, and the danger is extremely large. Pay attention to personnel protection when fighting. Some oxidants and organic peroxides can be saved with water or foam, while others cannot. Some can't be saved with carbon dioxide, and almost no acid-base fire extinguishing agent can be applied. The following basic countermeasures should be taken when encountering oxidant and organic peroxide fires:

Quickly identify the name, quantity, hazard, extent of combustion, path of fire spread, fire or foam suppression of oxidants and organic peroxides and other combustion products.

When it can be used for water or foam, it should do everything possible to control the spread of the fire, so that the fire zone is isolated and the combustion range is limited.

When it is not possible to use water, foam or carbon dioxide, use dry powder or cement or dry sand to cover it.

Leakage treatment

If oxidants and organic peroxides leak during transport, they should be carefully collected or absorbed using an inert material as an absorbent, and then rinsed with plenty of water as far as possible. It is strictly forbidden to use fuels such as sawdust and waste cotton yarn as absorbing materials to avoid ignition and ignition.

The collected spillage must not be reloaded into the original package or into the intact package to avoid danger by mixing impurities. It should be treated or considered to be buried underground in a safe and viable manner for its characteristics.

2. Fire treatment

(1) When an oxidant catches fire or is caught in a fire, oxygen is released to exacerbate the fire. Even in an inert gas, the fire will still burn: whether the cargo tank, container, warehouse is sealed, or steam, carbon dioxide, and other inert gases are used. Fire fighting is ineffective; it is also ineffective if you use a small amount of water to extinguish the fire; if you use a small amount of water to extinguish the fire, it will also cause a violent reaction of the peroxide in the product. Therefore, it is necessary to use a large amount of water or flooding to extinguish the fire, which is the most effective way to control the oxidant fire.

(2) Organic peroxides may cause an explosion when they are caught in fire or caught in a fire. Therefore, these packages should be quickly removed from the fire. Personnel should be as far away as possible from the fire and use a large amount of water to extinguish the fire in a protected location. Any organic peroxide package that has been caught in a fire or exposed to high temperatures, even if the fire has been extinguished, will violently decompose at any time when the package is not completely cooled. If possible, these packages should be disposed of under the technical guidance of a professional; if this is not possible, when transporting on water, consider throwing them into the water in case of emergency.

Sixth, the basic countermeasures for the fight against poisons and corrosives

Toxic and corrosive products have certain harm to the human body. Toxic substances are mainly caused by human oral poisoning by oral or inhalation of vapour or by skin contact. Corrosives are chemical burns caused by skin contact. Some poisons and corrosives can catch fire on their own, and some do not catch fire on their own, but they can catch fire when they come into contact with other combustible materials. The following basic countermeasures should generally be taken in the event of a fire in such items:

Firefighters must wear protective clothing and wear protective masks. Professional protective clothing should be used for fires with special items. Use oxygen or gas masks whenever possible in the fight against poisons.

First limit the range of combustion. Toxic and corrosive fires can easily cause casualties. After taking protective measures, firefighters should immediately invest in the work of injured and trapped people to reduce personal injury.

When using the rescue, try to use low-pressure water or misty water to avoid splashing of poisonous products and corrosives. In the case of acid-base corrosion products, it is preferred to prepare a neutralizing agent for dilution and neutralization.

In case of leakage of poisonous or corrosive containers, measures should be taken immediately after the fire extinguishing. Corrosive products need to be sealed with anti-corrosion materials. Concentrated sulfuric acid and nitric acid can release a lot of heat when exposed to water, which will cause boiling and splashing, and special attention should be paid to protection.

1. Poisoning fire emergency measures

Because most of the organic poisons are combustible and can produce a large amount of toxic or highly toxic gases when burning, it is very important to do emergency fire fighting measures when the poisons are on fire. Under normal circumstances, if it is a liquid poison, depending on the nature of the liquid (with or without water solubility and relative density), use anti-solvent foam or mechanical foam and chemical foam to extinguish the fire, or use sand, dry powder, stone powder and other measures; It is a solid poison that catches fire. It can be rescued by water, misty water or sand, dry powder or stone powder according to its nature.

2. Emergency measures when corrosives catch fire

Corrosive products are on fire. Generally, they can be used in the form of misty water or dry sand, foam, dry powder, etc. It is not advisable to use high-pressure water to prevent splashing of acid and harming people; sulfuric acid, halides, strong alkalis, etc. When an item that produces acid smoke from water catches fire, it cannot be rescued with water. It can be saved by dry sand, foam, dry powder, etc. Fire-fighting personnel should pay attention to anti-corrosion and anti-gas, wear anti-virus masks, anti-virus glasses or gas masks, rubber raincoats and long-sleeve rubber shoes, and wear anti-corrosion gloves. When the fire is extinguished, the person should stand in the upper wind. If the poisoned person is found, he should immediately be sent to the hospital for rescue and explain the name of the drug in order to facilitate the doctor's treatment.

Seven, the basic countermeasures for the fire of radioactive materials

Radioactive items are a special class of alpha, beta, gamma rays, and neutron streams that emit invisible human eyes that can seriously damage human life and health. In order to save such items, special measures must be taken to protect against radiation.

First, send a capable person to carry a radioactive test instrument to test the amount and range of radiation (agent). Testers must take protective measures.

★ For areas where the amount of radiation (agent) exceeds 0.0387C/KG, a warning sign "Life-threatening, no entry" should be set.

★ For areas where the amount of radiation (agent) is less than 0.0387C/KG, a warning sign "Life-threatening, Do not enter" should be set.

For radioactive materials that are not damaged on the burning site, wear protective equipment under the cover of the water gun and try to evacuate. When it is impossible to evacuate, it should be cooled on the spot to prevent new damage and increase the amount of radiation.

Do not move or impact the damaged container to prevent the spread of radioactive contamination.

8. Basic countermeasures for fighting fires of flammable solids and spontaneous combustion articles

Some flammable solids and pyrophoric materials are flammable in addition to air, water and acid, and they are also poisonous. Most of their combustion products are highly toxic, such as phosphorus in metals such as red phosphorus, yellow phosphorus and calcium phosphide. The chemistry itself is very toxic, and its combustion product phosphorus pentoxide and flammable hydrogen phosphine produced by moisture are highly toxic. The phosphine gas has a garlic-like odor, when the air contains 0.01 mg/L. Inhalation can cause poisoning. Therefore, when fighting fires of flammable solids, self-igniting articles and wet flammable materials, special attention should be paid to anti-virus and anti-corrosion. Wear certain protective equipment to ensure personal safety.

Flammable solid

When flammable solids are on fire, most of them can be saved with water, especially wet explosives and solids that may cause fire or cause fire by friction, and Class C flammable solids can be saved with water. For nearby foam fire extinguishers, carbon dioxide and dry powder Fire extinguishers can also be used for emergency purposes.

Naturally reactive substances such as aliphatic azo compounds, aromatic thiohydrazide compounds, nitroso compounds and diazonium salts (such as azobisisobutyronitrile, benzenesulfonyl hydrazide, etc.) The combustion does not require the participation of oxygen in the outside air, so the suffocation method is not available when the fire is on, and it is better to use a large amount of water to cool the fire. Powder fires of metal elements such as magnesium powder, aluminum powder, titanium powder, and zirconium powder cannot be used for water or carbon dioxide. Because such substances can generate a relatively high temperature when they are on fire, high temperature can decompose water molecules or carbon dioxide molecules, causing an explosion or making the combustion more violent. For example, when magnesium metal is burned, it can produce a high temperature of 2500 ° C, which will burn magnesium. When the strip is placed in a carbon dioxide gas, the oxygen in the magnesium and carbon dioxide react to form magnesium oxide, while producing amorphous carbon. Therefore, the metal element material can not be saved by water and carbon dioxide. Since the phosphide such as tetraphosphorus trisulfide or phosphorus pentasulfide is decomposed to produce flammable and toxic hydrogen sulfide gas in the presence of water or humid air, it is not possible to save water.

2. Self-igniting items

Yellow phosphorus can be rescued by water, and it is best to immerse in water; wet cotton, oil paper, oil silk, tarpaulin, celluloid chrome crumb, etc., which have the danger of heat and spontaneous combustion, can generally be saved with water.

X. Basic methods for fighting fires in wet and flammable materials

In case of wet flammable materials, it is absolutely impossible to use water and water-containing fire extinguishing agents. Carbon dioxide, nitrogen, halogenated alkane and other non-aqueous fire extinguishing agents are also not available. Because most of the wet and flammable materials are alkali metals, alkaline earth metals and compounds of these metals, they are not only flammable when exposed to water, but also produce relatively high temperatures during combustion. Most of these substances can react with carbon dioxide at high temperatures. The halogenated alkane reacts, so it cannot be used to save the fire from flammable materials.

For example, when carbon tetrachloride is contacted with burning sodium, a carbon mist is formed immediately, which makes the combustion more violent. Nitrogen is non-combustible, non-toxic, and non-aqueous. It is ok to fight the fire of flammable flammable products. However, because nitrogen and lithium metal direct compounds form lithium nitride, nitrogen and metal calcium can form calcium nitride at 500 ° C, and can not be used. From the current research results, the best fire extinguishing agent for the fire of flammable materials It is trimethyl metaborate. Dry sand, loess, dry powder and stone powder can also be used: for potassium and sodium fires, dry salt and graphite iron powder are also effective.

However, when metal lithium is on fire, if it is saved with dry sand containing SiO2, its combustion product Li2O can react with SiO2; if it is saved with sodium carbonate or salt, its high temperature of combustion can liberate sodium carbonate and sodium chloride from lithium. More dangerous sodium. Therefore, lithium metal is on fire, and it is not possible to use sand, sodium carbonate dry powder and salt to save. In addition, since the metal ruthenium can react with graphite to form ruthenium carbide, the metal ruthenium cannot be fired with graphite.

(Source: Chemical 707)

[Editor: Chen Guofang]

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