What is the main role of water in extinguishing fires?

1. Cooling effect.

The heat capacity of the water.

Compared with the heat of vaporization, water can capture a large amount of heat from the burning substance, reducing the temperature of the burning substance. Water encounters an increase in the temperature of the burning substance and is converted into water vapor.

When water vaporizes, it can absorb a particularly large amount of heat, so the water sprayed on the surface of the burning substance can make the temperature of the surface of the burning substance drop rapidly, play a role in cooling and cooling, and is conducive to extinguishing the fire.

2. Asphyxiation.

Water vaporization is formed into water vapor, which prevents the air from entering the combustion zone and reduces the oxygen content in the air in the combustion zone, which promotes combustion and extinguishes. When water comes into contact with the flame, the water droplets are converted into water vapor, which increases dramatically in size, and the water vapor dilutes the combustible gas.

and the concentration of combustible air in the combustion zone.

3. Emulsification.

When the water droplets meet the heavy oil, an emulsion layer will be formed on the surface of the oil, reducing the evaporation rate of the oil and gas and causing the combustion to stop.

Combustion requires the coexistence of three elements: combustibles such as fuel, combustibles such as oxygen, and temperature to reach the ignition point [1].

So: water can't react with oxygen, so it can't be burned, it's not a fuel.

Water splashed on a fire reduces the contact area between the fire source and the air, resulting in a lack of combustibles, just as sand can extinguish a fire.

Water can cool down: When water evaporates, it absorbs heat, and the temperature of the fuel can be kept below the ignition point (the main principle of firefighters using fire hoses to extinguish fires is to lower the temperature of the fire source to make it lower than the ignition point).

The above three points are only for flames that can be doused with water. There are situations where water cannot be used to extinguish fires, and the use of water will only promote combustion.

Water may not be able to extinguish liquid (Class B) fires, depending on the polarity of the liquid burning molecules. Water can extinguish fires from polar fuels (e.g. alcohol), but when used on non-polar fuels (e.g. fuel oil), it spreads out and makes them more uncontrollable.

Cooling. The extinguishing effect of water spray is due to the combined effect of liquid phase heat absorption (cooling), vapor phase inerting and droplet momentum. The effect of liquid-phase cooling on the surface of the fuel is usually most pronounced.

The principle of water fire extinguishing is to reduce the ambient temperature of the fire source and isolate the air.

Because water evaporation absorbs a lot of heat, and the temperature of water is stable at 100 degrees when it boils, the ignition point of many burning objects is higher than 100 degrees, since the temperature is kept at 100 degrees, then below the ignition point of the object, the object stops burning.

In addition, most objects need to be combined with oxygen in the air to continue burning, and the water covers the surface of the object, and the object and oxygen cannot be contacted, so the combustion stops.

Some objects, such as magnesium metal, can continue to burn in the presence of water, gasoline and diesel are less dense than water and are not soluble in water, and will float on the surface of the water after watering, and will continue to burn if it does not have the effect of isolating oxygen, so it is also necessary to extinguish the fire with water according to the actual situation.

The core principle of water being able to extinguish fires is to use the physical and chemical properties of water to stop combustion. First of all, the physical properties of water are manifested in the fact that it can reduce the temperature of the burning object, thereby slowing down or stopping the spread of the flame, but this is only a superficial phenomenon. Secondly, water also plays a role in chemical reactions, using the "thermal stability" in the chemical reaction of the sakino to inhibit the generation of flames.

Specifically, the physical action of water is to hinder the growth of a fire by absorbing and diffusing heat. When water is sprayed on a fire scene, it can absorb the heat released by the surrounding burning objects, carry the heat away and equilibrate the temperature. In this way, the ignition source and the surrounding material cannot reach the temperature required for combustion, and the combustion cannot continue.

As a result, water can physically slow down or eliminate the development of fire.

In addition, water also plays a role in chemical reactions. When water evaporates, it needs to absorb a lot of energy, and the evaporation of water can kill the source of ignition. Water dilutes the oxygen in the air around the flame, which not only slows down the combustion, but also makes it difficult for the burning object to release incomplete combustion gases, such as carbon monoxide.

At the same time, the oxygen molecules in the water and the hydrogen and hydrocarbons in the ignition source can react to form weak ionic bonds, which inhibits the expansion of the fire to a certain extent.

Therefore, water fire extinguishing is a complex process that involves both physical phenomena and chemical reactions. In addition to the above two ways, water also has other functions, such as the alkalinity of sodium carbonate aqueous solution can also inhibit acid fire, but it is all around the principle of slowing down the fire, eliminating thinking and other auxiliary slowing down combustion.

In short, the core of the principle that water can extinguish fires is to stop the spread of flames by controlling temperature, diluting oxygen in the air, and inhibiting the chemical reaction of fire. It involves both physical and chemical aspects, and is a very effective and common way to extinguish fires. <>

What does the water need to rely on to extinguish the fire, and what does the main ship Zheng rely on for leakage?

a.Water is heated and evaporated to produce water vapor air, which reduces the content.

b.Water absorbs a large amount of heat from combustion, reducing the temperature of the ignition to below the ignition point.

c.Water adheres to the surface of the fire, so that the combustibles do not come into contact with the air.

Correct answer: B