What are the principles of foam fire extinguishers?

In addition to the two reactants, some blowing agents are added to the fire extinguisher.

The principle of foam fire extinguisher fire extinguishing is that when extinguishing the fire, a large amount of carbon dioxide and foam can be sprayed, which can adhere to the combustibles, so that the combustibles are isolated from the air to achieve the purpose of extinguishing the fire.

Foam fire extinguishers are divided into: portable foam fire extinguishers, cart foam fire extinguishers and air foam fire extinguishers. Foam fire extinguishers should be stored in a dry, cool, ventilated and convenient place, not close to high temperature or places that may be exposed to the sun to prevent carbonic acid decomposition and failure; In winter, anti-freezing measures should be taken to prevent freezing; And the dust should be wiped frequently, and the nozzle should be dredged to keep it unobstructed.

The foam fire extinguisher is filled with liquid carbon dioxide. Carbon dioxide cannot spontaneously combustible or support combustion, and it is heavier than air, and it presses on the burning object together with the foam, absorbing a large amount of heat, and the temperature of the burning object drops sharply, so the fire is quickly extinguished.

The sprayed foam, they can adhere to the combustibles, isolate the combustibles from the air, and at the same time reduce the temperature, destroy the combustion conditions, and achieve the purpose of extinguishing the fire.

Foam fire extinguisher principle used in junior high school:

na2co3 + 2hcl = 2nacl + h2o + co2↑

High School (Actual) Foam Fire Extinguisher Principle:

The foam fire extinguisher is filled with saturated aluminum sulfate solution and sodium bicarbonate solution, and sodium carbonate solution cannot be used. They are packed in different containers, each with the following chemical equation for hydrolysis:

al2(so4)3+6h2o﹤=﹥2al(oh)3+3h2so4

nahco3+h2o﹤=﹥naoh+h2co3

When the two solutions are mixed, the following reaction occurs, 2NaOH + H2SO4 = Na2SO4 + 2H2O

Due to the above reaction, the hydrolysis of Al3+ and HCO3- tends to be completed, and a large amount of H2CO3 is generated and then decomposed into water and CO2, so that the pressure in the fire extinguisher increases, and the generated products are sprayed out together, covering the ignition substance to extinguish the flame. The total chemical equation is:

al2(so4)3+6nahco3=3na2so4+2al(oh)3↓+ 6co2↑

Homes or cars will be equipped with fire extinguishers, once a fire occurs, fire extinguishers can play a great role, so we need to understand the principle of foam fire extinguishers and how to use fire extinguishing, so that they can be better used.

1. What is the principle of foam fire extinguisher?

1. The reason why the foam fire extinguisher can extinguish the fire is mainly because there is a large amount of carbon dioxide inside, and a lot of foam will be produced, which can cover the fire and block the air.

2. Foam fire extinguishers are more suitable for extinguishing fires caused by wood, cotton, linen, etc., including fires caused by oil or grease. If there is a fire in the kitchen, because there are some appliances or there is some flammable liquid, this foam fire extinguisher can be used.

2. How to use foam fire extinguishers correctly.

1. You need to lift the handle on the foam fire extinguisher, and then you need to pull out the safety bolt on it, you will find that there is a small iron ring on it, and drag it.

2. Then aim it at the flame, generally speaking, the distance should reach about 5 meters, and you can stand upwind to spray the fire until the fire is extinguished.

3. Types of fire extinguishers.

1. Portable foam fire extinguisher, generally speaking, this foam fire extinguisher can extinguish fires caused by oil or other substances. When using, you only need to hold its iron ring, and then pull out the safety bolt, and then you can aim at the fire source to extinguish the fire.

2. Portable carbon dioxide fire extinguisher, this fire extinguisher can be used for fires caused by electronic equipment or electrical appliances, it has two ways, one is the hand wheel type, and the other is the duckbill type.

3. Dry powder fire extinguisher, if it is oil or electrical equipment, it can also be used for fire. The method of use is also relatively simple, you need to open the safety plug, and then hold its nozzle and aim it at the fire source to extinguish it.

The above content is about the principle of foam fire extinguishers and how to use foam fire extinguishers correctly, what other types of fire extinguishers are on the market, we can choose to buy according to our needs.

The principle equation of foam fire extinguisher: Al2(SO4)3+6NaHCO3==3Na2SO4+2AL(OH)3 +6CO2.

When the foam fire extinguisher extinguishes the fire, it can spray a large amount of carbon dioxide and foam, which can adhere to the combustibles, so that the combustibles are isolated from the air to achieve the purpose of extinguishing the fire. It can be used to extinguish fire extinguishing caused by the burning of wood, cotton cloth, etc. Foam is often used on top of Class B fires and can also be used in Class A fires.

Usually foam extinguishing agent is water added to the foaming agent so that the foam can float on top of the burning liquid and isolate the fire and the burning surface.

Foam fire extinguisherThe chemical reaction occurs by mixing the acidic solution and the alkaline solution in the cylinder, and the generated foam is pressed out of the nozzle and sprayed out for fire extinguishing. In addition to being used to extinguish general solid matter fires, it can also extinguish combustible liquid fires such as oil, but it cannot extinguish fires caused by live equipment (except for the use of special nozzles) and organic solvents such as alcohols, ketones, esters, ethers and other alcohols (except for anti-solvent foam fire extinguishing agents). There are three types of foam fire extinguishers: MP type portable type, MPZ type portable boat type and MPT type cart type.

The principle is to use foam (CO2) to spray onto the surface of the combustible material to isolate the air, so that the combustible material lacks oxygen and extinguishes the fire.

The chemical equation is expressed as:

Step 1: 3Na2CO3 + Al2(SO4)3 = 3Na2SO4 + Al2(CO3)3

Step 2: Al2(CO3)3+6H2O=2Al(OH)3+3H2O+3CO2