The foam sprayed by chemical foam extinguisher is chemical foam. The difference between chemical foam and air foam is that the gas contained in chemical foam is carbon dioxide gas; And that gas contain in the air foam is air. There are two kinds of chemical foam extinguisher: portable and cart.
The foam sprayed by chemical foam extinguisher is chemical foam. The difference between chemical foam and air foam is that the gas contained in chemical foam is carbon dioxide gas; And the gas contained in the air foam is air. There are two kinds of chemical foam extinguisher: portable and cart.
A) Portable chemical foam extinguisher
The portable chemical foam extinguisher consists of a cylinder, a cylinder cover, a nozzle and a bottle liner. Usually, the bottle is filled with aluminum sulfate solution, and the cylinder is filled with sodium bicarbonate solution. When the fire extinguisher is inverted, the two solutions mix, resulting in a chemical reaction and spraying foam. In the process of foam spraying, the fire extinguisher should always be in an inverted vertical state, and cannot be placed horizontally or vertically, otherwise the spraying will be interrupted. If the fire of combustible solid materials is extinguished, the nozzle should aim at the most violent crack; If the oil fire in the container is put out, foam should be sprayed on the container wall to make the foam flow down the wall; If the flowing oil fire is put out, the operator should stand in the upwind direction and try to reduce the angle between the foam jet and the ground, so that the foam will gradually cover the whole oil surface from near to far.
H) Maintenance and inspection of foam extinguisher.
For the maintenance of fire extinguishers, the following points should be noted:
(1) The storage temperature should be between-8 and 45℃.
(2) The location of the fire extinguisher should be easy to access, and at the same time, it should be cool, dry and ventilated to prevent the fire extinguisher from corrosion or rust.
(3) Always check whether the nozzle of the fire extinguisher is blocked. If it is blocked, it should be unblocked in time.
(4) Always check whether there is rust or damage on the fire extinguisher, and whether the surface paint falls off, and repair it in time if it falls off slightly; If there is obvious corrosion, it should be sent to the professional maintenance department for inspection.
⑤ Conduct regular inspection once every six months. The inspection contents are as follows:
Remove the cylinder head, and check whether the filter screen is firmly installed, whether the filter screen is blocked, whether the sealing rubber gasket of the cylinder head is damaged, and whether there is dislocation during assembly.
Cart fire extinguisher, check whether the sealing ring of the bottle mouth is corroded, whether the spray gun, spray hose and safety valve are blocked, and whether the wheels on the frame are flexible and reliable.
6. For chemical foam extinguisher, chemicals should be checked once a year.
Use of foam extinguisher 2 Foam fire extinguishing agent is an effective flammable liquid fire extinguishing agent. It mainly produces a condensed foam floating layer on the liquid surface, which plays the role of suffocation and cooling.
1. Classified by mixing ratio
According to the mixing ratio of foam liquid and water, foam extinguishing agents can be divided into 1.5%, 3% and 6% types.
2. Classification by foaming multiple
According to its foaming multiple, foam extinguishing agents can be divided into three categories: low-multiple foam extinguishing agents, medium-multiple foam extinguishing agents and high-multiple foam extinguishing agents. The foaming multiple of low-expansion foam extinguishing agent is generally 20 times.
The foaming multiple of medium-multiple foam extinguishing agent is between 20 and 200 times, and that of high-multiple foam extinguishing agent is generally between 200 ~ 1000 times.
3. Classification according to usage characteristics
Foam extinguishing agents can be divided into Class A foam extinguishing agents and Class B foam extinguishing agents according to their use places and characteristics, and Class B foam extinguishing agents can be divided into water-insoluble foam extinguishing agents (such as protein foam extinguishing agents, fluoroprotein foam extinguishing agents, and? Light water? Foam extinguishing agent) and anti-soluble foam extinguishing agent (gel anti-soluble foam extinguishing agent, water film anti-soluble foam extinguishing agent, fluorine protein anti-soluble foam extinguishing agent, film-forming fluorine protein anti-soluble foam extinguishing agent, medium multiple anti-soluble foam extinguishing agent).
4. According to the matrix classification of synthetic foam
Foam extinguishing agent can be divided into protein foam extinguishing agent and synthetic foam extinguishing agent. Protein foam fire extinguishing agents mainly include ordinary protein foam fire extinguishing agents, fluoroprotein foam fire extinguishing agents, film-forming fluoroprotein foam fire extinguishing agents, and anti-dissolution and anti-dissolution foam fire extinguishing agents. Synthetic foam fire extinguishing agents mainly include high multiple foam fire extinguishing agents, high, medium and low multiple universal foam fire extinguishing agents, water film-forming foam fire extinguishing agents, water-soluble film-forming fire extinguishing agents and Class A fire fighting foams.
Ordinary foam extinguishing agent
A, chemical foam extinguishing agent
1. Composition and function
Aluminum sulfate and sodium bicarbonate are still used as foaming agents, and fluorocarbon surfactants and hydrocarbon surfactants are added as synergists.
Step 2 perform
It has the characteristics of low viscosity, good fluidity and self-sealing ability, high fire extinguishing efficiency and so on. Its fire extinguishing efficiency is 2 ~ 3 times that of the same amount of yp chemical foam extinguishing agent. Moreover, all synthetic raw materials are used, which is not easy to deteriorate and has a long shelf life.
Fire extinguishing principle
When in use, the aqueous solution of acidic agent and alkaline agent is mixed as much as possible, and the carbon dioxide generated by the reaction, on the one hand, forms a large number of fine foams in the solution; At the same time, the pressure in the fire extinguisher rises rapidly, and the generated foam is sprayed from the nozzle. Colloidal aluminum hydroxide generated by the reaction is distributed on the foam film, which makes the foam have certain viscosity and easy to attach to the combustion products, thus enhancing the thermal stability of the foam. The fluorocarbon surfactant in the preparation will reduce the surface tension and critical micelle concentration of the fire extinguishing agent solution, and it is easy to form bubbles. At the same time, the diffusion coefficient of the solution can be positive, forming a water film on the surface of the water-insoluble flammable liquid; Hydrocarbon surfactants can stabilize foam and play a certain auxiliary role in film formation.
5. Storage method
The oral and external preparations must be packaged separately, and the minimum packaging unit is the dosage required for each fire extinguisher. All of them are packed in polyethylene or PVC plastic bags, and then packed in cartons or wooden cases respectively. Moisture and exposure should be avoided during transportation.
Chemical foam extinguishing agent should be stored in a cool place. In a dry warehouse; Internal and external preparations should be stacked separately, and the stacking should not be too high.
6. Validity period
After the chemical foaming agent is prepared, it is put into a fire extinguisher, and the validity period is one year.
The foam of chemical foam fire extinguishing agent is produced by the chemical reaction of aqueous solutions of two chemicals. Because of its poor fire extinguishing effect, strong corrosiveness, short shelf life and harmful to human body and environment, it has been stopped for many years in China.
Second, the air foam extinguishing agent
The foam of air foam fire extinguishing agent is produced by stirring. According to its foaming multiple, it can be divided into three types: low multiple foam, medium multiple foam and high multiple foam. According to the types and uses of foaming agents, low expansion foam fire extinguishing agents can be divided into five categories: protein foam, fluoroprotein foam, water film foam, soluble foam and synthetic foam fire extinguishing agents.
1. protein foam extinguishing agent
Protein foam extinguishing agent is the most basic kind of foam. It is divided into animal protein and plant protein. Its main components are water and hydrolyzed protein, and appropriate additives such as stabilizer, antifreeze, slow-release agent, preservative and viscosity control agent are added. It is a dark brown viscous liquid with the smell of natural protein decomposition. The foam solution also contains a certain amount of inorganic salts, such as sodium chloride and ferrous sulfate. Usually stored in packaging barrels or storage tanks, it is mixed with pressurized water flow in a ratio of 6: 94 or 3: 97 through a proportional mixer to form a mixed liquid. When the mixed liquid flows through the foam pipe gun or foam generator, air is sucked in, and after mechanical stirring, foam is generated and sprayed into the combustion area to put out the fire.
1922, Jennings of American Standard Oil Company injected animal glue and ferrous sulfate on the surface of gasoline to prevent gasoline from evaporating and catching fire, which was the earliest use of protein foam to put out the fire in the world. Later, Wiesenbaum and Sperma found that protein's water decomposition products were the best foam extinguishing agents. They regard protein water decomposition product and sulfuric acid sub-aqueous solution as two kinds of aqueous solutions respectively. When in use, they mix them together, inhale air and stir them into foam. Later, they added ferrous sulfate to the hydrolysate of protein and used it as a thickener to develop the current protein foam. Their concentration of 5% is mixed with fresh water and seawater to produce 8 times of foam, which can stay on the surface of oil stably. Stama company in Hamburg, Germany, is still selling this foam liquid.
(1) fire extinguishing principle
The specific gravity of air foam produced by it is light (generally 0. 1 ~ 0. 5) It has good fluidity, strong flame resistance, is not easy to disperse, and can quickly form a covering layer on the surface of water-insoluble liquid to quickly extinguish the fire. Because protein foam can also adhere to the vertical plane, it can also put out the fire of general solid substances. At present, protein foam is mainly used to put out oil fires.
(2) Features
The advantages of protein foam are readily available raw materials, simple production process, low cost, good foam stability, low requirements for water quality and good storage performance. However, compared with other foams, the foam has poor fluidity and low oil pollution resistance, so it can not be used for underwater spray fire extinguishing, nor can it be used in conjunction with dry powder fire extinguishing agent (its foam is quickly destroyed after contact with dry powder), and it is mainly used to put out oil fires.
(3) Scope of application
It is mainly used to put out fires of flammable and combustible liquids that are generally insoluble in water, and can also be used to put out fires of combustible solid substances. Because of its good thermal stability and covering performance, it is also widely used to put out fires in oil storage tanks or spray foam into unlit oil tanks to prevent radiant heat from igniting nearby burning oil tanks. When using protein foam to rescue the fire of crude oil and heavy oil storage tanks, attention should be paid to the possibility of oil foam boiling or splashing.
2. Fluoroprotein foam extinguishing agent
1965, the national foam company of the United States developed fluoroprotein foam, and the commodity was aer-o-foamxl. Fluoroprotein foam has good fluidity and is not easy to defoam when it is polluted by oil, so it can be used in the form of underwater spray. Then Britain's national foam company, Angus company and ici company also made fluoroprotein foam liquid, which was sold in the market as fp-70. In Europe and America, after the advent of fluoroprotein foam, it quickly replaced protein foam as the mainstream fire extinguishing agent to protect large oil tanks.
(1) component
Add it to protein foam? 620 1? Prefabricated liquid can be used as fluoroprotein foam extinguishing agent. ?
620 1? Prefabricated liquid, also known as fcs solution, is made of? 620 1? Aqueous solution of fluorocarbon surfactant, isopropanol and water with the mass ratio of 3: 3: 4.
? The weight percentages of 620 1 fluorocarbon surfactant in 6% and 3% fluoroprotein foam liquid are 0.33% and 0.66% respectively. Therefore, the content of 620 1 fluorocarbon surfactant in the two fluoroprotein foams produced according to the prescribed mixing ratio is 0.0 196%(wt%).
(2) Fire extinguishing principle and foam characteristics
The fire extinguishing principle is basically the same as that of protein foam. However, due to the effect of fluorocarbon surfactant, the properties of its aqueous solution and foam have changed significantly, thus improving the fire extinguishing efficiency.
① The surface tension and interfacial tension of the aqueous solution are obviously reduced: the experiment shows that the surface tension dimension of the aqueous solution prepared by mixing protein foam solution and water according to the specified mixing ratio is 46? 10-5n/cm, and the aqueous solution of fluoroprotein foam fire extinguishing agent prepared according to the specified mixing ratio is in? The surface tension is 620 1, the obs content is 0.0 15% and only 2 1? About 10-5n/cm. Besides,? 620 1? Obs can also reduce the interfacial tension between fire extinguishing agent aqueous solution and oil. The decrease of surface tension and interfacial tension means that the energy required to produce foam is relatively reduced.
② Foam is easy to flow: the critical shear stress of foam is directly related to the fluidity of foam. The smaller the shear stress, the better the fluidity of foam. The critical shear stress of protein foam is 200? About10-5n/cm; The critical shear stress of fluoroprotein foam is only 100.
? About 10-5n/cm. Therefore, the fluidity of fluoroprotein foam is much better than that of protein foam. Fluoroprotein foam can quickly cover the oil surface with a thin foam layer when extinguishing fire, and the foam is firm and not easy to be destroyed; Even if it is broken, it can heal itself quickly because of its good liquidity and strong self-healing ability.
(3) Foam has a strong oil repellent ability: during fire extinguishing, due to the impact between foam injection and oil surface, part of foam often dives into the oil and carries a certain amount of oil to the oil surface. When protein foam contains a certain amount of oil, it can burn freely, so it cannot be used for underwater spraying. When using fluoroprotein foam to extinguish fire, because the fluorocarbon chain in fluorocarbon surfactant molecules is hydrophobic and oleophobic, a water film can be formed at the interface between foam and oil, and oil droplets are wrapped in the foam, which prevents the evaporation of oil and reduces the flammability of oil-containing foam. The experiment shows that protein foam is flammable when the gasoline content reaches more than 2%, and can burn freely when it reaches 8.5%. However, the gasoline content in fluoroprotein foam needs to be as high as 23% or more to burn freely.
④ Good compatibility with dry powder: protein foam cannot be combined with general dry powder.
Because the moisture-proof agent (such as magnesium stearate) used in dry powder has a great destructive effect on foam, once the two contact, the foam will be destroyed and disappear quickly, so protein foam can only be used with special powder. Fluoroprotein foam has the ability to resist the destruction of dry powder because of the function of fluorocarbon surfactant. When the protein foam contains 0.0 1% of 620 1 or obs, it has obvious resistance to dry powder destruction; What time? 620 1? Or when the obs content reaches 0.0 15 ~ 0.02%. It has a good combination with dry powder. Therefore, fluoroprotein foam fire extinguishing agent can be used in combination with various dry powders, and all of them can achieve good fire extinguishing effect. Dry powder extinguishing agent has fast fire extinguishing speed and can extinguish fire quickly; Foam covers the oil surface to prevent re-ignition. Combine the two and give full play to their respective strengths. You can put out the fire quickly.
(4) Scope of application
Like protein foam fire extinguishing agent, it is mainly used to extinguish all kinds of water-insoluble flammable and combustible liquids and some combustible solid fires. It is widely used for fire fighting in large storage tanks (underwater spraying), bulk warehouses, transportation transit devices, production and processing devices, oil terminals, airplanes and other places. Its use method and storage requirements are the same as those of protein foam.
3. Water film foam extinguishing agent
Water foam was invented in America. In 1946-1952, Twiss Mann of the U.S. Naval Technology Institute found that fluorine-containing surfactants have both water repellency and oil repellency. In this research, fluorine surfactant was used as fire extinguishing agent, and a combined system with dry powder fire extinguishing agent was developed. The aqueous solution of fluorine-containing surfactant precipitated from this foam forms a thin film on the oil surface and floats on it, thus inhibiting steam generation and preventing re-ignition after fire fighting. Because it forms a light water-based film on the surface of oil, the US Navy calls it light water foam, and the patent number is 1964.
(1) component
It consists of fluorocarbon surfactant, hydrocarbon surfactant and additives (foam stabilizer, antifreeze, cosolvent, thickener, etc.). ) and water. Mainly fluorocarbon surfactant, accounting for1~ 5%; It can be a mixture of one or more surfactants. Its hydrophilic group can be cation or anion, amphoteric or nonionic, and anion is the most commonly used. The water film foam fire extinguishing agent also contains 0. 1 ~ 0.5 of polyethylene oxide to improve the anti-re-ignition ability and self-sealing ability of the foam.
The content of fluorine-free surfactant used in water-formed foam extinguishing agent is 0.0 1 ~ 0.5%. It can not only enhance the foaming multiple and stability of foam, but also reduce the interfacial tension between water-formed foam aqueous solution and oil, enhance the affinity with oil, and contribute to the formation and diffusion of water film, so that some fluorocarbon surfactants that cannot form diffusion films can also form films better and form solid water-containing films.
The solvents in water-formed foam are ethylene glycol butyl ether, diethylene glycol butyl ether, etc. And the dosage is 5-40%. They can solubilize all components, enhance foam performance, appropriately reduce the freezing point of foam solution, and contribute to the formation of foam.
(2) Fire extinguishing principle
When fighting the fire of petroleum products, foam plays a leading role, relying on the dual role of foam and water film.
① Fire extinguishing function of foam: due to the effect of fluorocarbon surfactant and other additives in water film foam, it has a lower critical shear stress (its critical shear stress is only 60? About 10-5n/cm), when the foam is sprayed on the oil surface, it spreads quickly on the oil surface because of its excellent fluidity, and with the action of water film, the fire is quickly extinguished.
(2) the fire extinguishing function of water film; The characteristic of water-borne foam is that it can form a thin water film on the surface of oil, which is the result of the interaction between fluorocarbon surfactant and fluorine-free surfactant.
This kind of water film can isolate oil from air, prevent oil and gas from evaporating, and is more conducive to foam flow and accelerate fire fighting. However, water film alone cannot effectively extinguish the fire. In fact, the fire extinguishing function of water foam is that when the foam is sprayed on the burning oil surface, the foam will spread on the oil surface, forming a water film on the oil surface, inhibiting the evaporation of oil products, isolating them from the air, and making the foam quickly flow to the area that is not directly sprayed, thus further extinguishing the fire.
4. Insoluble foam extinguishing agent
Water-soluble flammable liquids, such as alcohols, esters, ethers, aldehydes, organic acids, amines, etc., because of their strong molecular polarity, can absorb a large amount of water in the foam, so that the foam will be destroyed quickly and can not play a fire extinguishing role, so protein foam, fluoroprotein foam and? Light water? Foam is used to put out this liquid fire, but soluble foam must be used to put out the fire.
The main types of anti-soluble foam fire extinguishing agents are as follows: ① Metal soap anti-soluble fire extinguishing agents made of hydrolyzed protein and organic metal salts of fatty acids such as zinc, cadmium and aluminum have been eliminated at present; (2) A polymer anti-soluble foam extinguishing agent made of hydrolyzed protein or synthetic surfactant as foaming agent and natural polymer compounds such as alginate; (3) thixotropic anti-soluble foam fire extinguishing agent made of fluorocarbon surfactant and polysaccharide; (4) Fluoroprotein-type anti-soluble foam extinguishing agent made of protein foam liquid, special fluorocarbon surfactant and various metal salts; ⑤ Insoluble foam extinguishing agent based on silicone surfactant.
Fire extinguishing principle: when the stock solution is diluted with water, no precipitation will occur, and the mixed solution is transparent and homogeneous. As soon as the foam touches the surface of water-soluble solvent, it reacts immediately, taking away the moisture in the foam layer and forming a uniform and viscous film, which is insoluble in water and solvent. Thereby effectively preventing the water-soluble solvent from damaging the foam and improving the stability and durability of the foam. When putting out a fire, foam quickly covers the liquid surface or adheres to the solid surface of combustion products, forming a tight covering layer, thus isolating the air and extinguishing the fire.
Application: Anti-soluble foam is mainly used to preserve ethanol, methanol and acetone. Fire of common water-soluble flammable liquids such as ethyl acetate. It should not be used to put out fires of organic liquids, such as aldehydes, ethers, organic acids and amines with low boiling points. Although it can also put out general oil and solid fires, it is generally not used because of its high price.
Usage characteristics; The fire extinguishing agent is rich in raw materials, simple in manufacturing process, low in price, low in foam corrosiveness, long in validity period, premixed with water, and unlimited in conveying distance of mixed liquid. It can be used for ordinary foam fire extinguishing equipment, as well as fixed, semi-fixed or mobile fire extinguishing systems. When in use, it is still necessary to install a foam buffer device.
Fire extinguishing principle: When putting out a fire, foam can form a gel layer containing bubbles on the surface of polar solvents, which can effectively prevent the destruction of polar solvents, thus achieving the purpose of covering the fire site.
Usage: general fire extinguishing equipment can be used and can be premixed; If the U-shaped nozzle is used, the foam will flow in along the container wall at a distance of 40 cm from the liquid level, and the effect is the best. In practical use, the mixing ratio of 9% and 6% can achieve good fire extinguishing effect.
Scope of application: This soluble foam extinguishing agent is mainly used to extinguish fires in polar solvents such as methanol, ethanol, ether and acetone.
5. High expansion foam extinguishing agent
In the 1960s, high multiple foam and its application technology developed rapidly in Britain, America, Sweden, Japan and other countries. It uses synthetic surfactant as the base material, and can emit 500 ~ 1000 times of foam through a high-magnification foam generator, and quickly fills the protected area and space with a large amount of foam.
Isolate the oxygen (air) needed for combustion and put out the fire. In addition, the high multiple has the function of cooling and preventing heat conduction in the fire. Since 1970s, China has successively developed a series of high-rate foam products, such as fresh water type, seawater type, smoke-resistant and temperature-resistant type, and developed corresponding fixed fire extinguishing systems for above-ground and underground buildings, gradually realizing the standardization and serialization of application technology.
(1) component
Generally, it consists of foaming agent, fixing agent, solvent, antifreeze, hard water softener and additives.
(2) Main performance indicators
Its appearance should be homogeneous liquid, no obvious toxicity and biodegradable; Its use temperature range is -5 ~-40℃ for common type,-10 ~ 40℃ for cold-resistant type and -20 ~ 40℃ for ultra-cold-resistant type.
(3) Fire extinguishing principle
The aqueous solution of high-expansion foam fire extinguishing agent is produced by high-expansion foam generator, and its foaming multiple is as high as 200 ~ 1000 times. The bubble diameter is generally above 10 mm. Due to its large volume expansion and a large amount of foam generated by the high multiple foam generator (the large foam can generate more than 1000m3 within 1min), the foam can quickly fill the ignition space, cover the combustion products and isolate the combustion products from the air. After the foam is heated, a lot of water vapor absorbs a lot of heat, which makes the temperature in the combustion zone drop sharply, dilutes the oxygen content in the air, prevents heat conduction, convection and heat radiation in the fire, and prevents the fire from spreading. Therefore, the high multiple foam fire extinguishing technology has the characteristics of small supply intensity of mixed liquid, large supply of foam, rapid fire extinguishing, safety and reliability, less water damage and simple on-site treatment after fire extinguishing.
(4) Scope of application
It is mainly suitable for extinguishing water-insoluble flammable and combustible liquid fires and general solid material fires (such as the fire in which oil tanks flow to fire dikes or the fire in which rotating machinery leaks combustible liquid). ), as well as warehouses, hangars, basements, underground tunnels, mines, ships and other limited space fires. When the storage tank of cryogenic liquid such as liquefied natural gas leaks, high expansion foam can also be used to prevent steam volatilization and fire.
Because of its low specific gravity and good fluidity, it can be transported to a certain height or a far place to put out the fire under the action of foam-producing airflow through appropriate pipelines.
When the oil tank is on fire, the lift of the rising air above the oil tank is very large, but the specific gravity of foam is very small, so it is impossible to put out the oil tank fire with high multiple foam extinguishing agent. But for a small amount of water-soluble flammable liquid fire stored indoors, sometimes it can be put out by total flooding.
When using high expansion foam to extinguish fire, attention should be paid to prevent the gas entering the high expansion foam generator from containing combustion gas, smoke and acid gas, so as not to destroy the foam.
(5) storage
In the process of transportation and storage, other types of fire extinguishing agents shall not be mixed, and should be placed in a cool and dry place to prevent sun exposure; The storage environment temperature should be within the specified range, and after two years of storage, a comprehensive quality inspection should be carried out, and its performance index should not be lower than the requirements of the specified standards.
According to the national standard: gb 15308-2006 foam extinguisher, the validity period of protein foam fire extinguishing agent and fluoroprotein foam fire extinguishing agent is 2 years, but under good preservation conditions, the validity period can be up to 3 years. According to national regulations, the validity period of water-based foam extinguishing agent is 8 years, but the longest validity period can reach 10- 15 years under good storage conditions. According to the national regulations, the validity period of anti-soluble foam extinguishing agent is 2 years, but the longest validity period can reach 3 years under good storage conditions. The validity period of high-expansion foam extinguishing agent stipulated by the state is 3 years;