Water and water-based fire extinguishing agents

Water has a strong ability to absorb heat, the burning material has a significant cooling effect, water vaporization produces a large amount of water vapor, crowding and prevent air from entering the combustion area, which can reduce the content of oxygen in the combustion area. In addition, water is cheap and easy to obtain, a wide range of sources, the pollution of the environment is small. Therefore, water is used to fight fires most widely, the most versatile fire extinguishing agent.

1. The form of water and its scope of application
2. Direct flow and bloom water

Pressurized by the pump and sprayed by the DC water gun column water flow is called straight water, sprayed by the blossom water gun drop water called blossom water (blossom water droplet diameter is generally greater than 100μm). Straight flowing water and blooming water can be used to put out general solid materials such as coal, wooden items, grain, cotton, linen, rubber, paper, and other fires; can also put out the flashpoint of 120 ℃ or more, at room temperature is the semi-consolidated state of heavy oil fires.

2. Fog water

Sprayed by the spray gun, water droplets less than 100μm in diameter water flow is called fog water. With the same volume of water sprayed with fog, you can get a much larger surface area than straight water or bloom water, greatly improving the contact area of water and combustion or flame, which is conducive to the penetration of water on combustion. Therefore, fog water cooling fast, high efficiency of fire extinguishing, water damage loss is small. A large number of tiny droplets of water is also conducive to the adsorption of soot, so it can be used to fight dust fires, fibrous materials, and grain pile hoarding, and other solid combustible fires; and because the tiny droplets of fog do not contact each other, the range is close, can not be used at a distance.

3. The scope of application of different forms of water

Water jet to the burning area of the form, can be intensive jets, blooming water and spray water, water-intensive convection through the burning area, a few do not play a role, and the jet itself is not subject to the beginning of the fire and the burning material interaction, the role of water on the material is not very effective, water jets between, or jet stream, the same do not have any role in each other, neither affect the state of the gas (or combustible Gas mixed with the state of this too) nor is the gas particularly affected. When the water-intensive jet and strong combustible gas jet (at the mouth of the object, the rate of airflow is very large, gas density is also large, and the gas-dynamic pressure head is also very large) interaction, the water jet will be broken, and if the amount of broken, can break the well jet gas flow. However, under fire conditions, this process is difficult to control and difficult to adjust. Therefore, it is best not to shoot a dense stream of water at a burning gas flame. When fighting flammable and combustible liquid fires, intensive water flow to the flame also does not play any role, the waterfalls on the flammable and combustible liquid surface, its cooling effect is very poor. Because of the density of water than combustible hydrocarbon material, it can quickly sink, it cools the surface of combustible liquids is not as effective as the role of blooming water and spray water. Fight the solid combustible material fire, will be intensive water jet to the flame, but also with the aforementioned two cases, will not affect the burning area, and when the waterfalls on the surface of solid materials, its cooling effect is not very good, and therefore poor fire extinguishing effect.

But in the following cases can use intensive water flow.

① When you must lift the bottom edge of the flame fire column, that is, in order to expand the “dead zone” when. For example, the explosive explosion method or with the help of turbojet fire truck to fight fires, the need to lift the flame with intensive water flow; in order to put the fire fighting technology equipment into combat positions, in order to make the rescue and recovery operations of technical equipment into the scene, etc…

② When the fire-fighting personnel can not approach the spray well for fire-fighting operations, in order to ensure that the combat operations and auxiliary operations for fire-fighting; to protect the adjacent objects from catching fire, etc.

③ with a strong intensive water flow can put out the fire of wood stacks, because in this violent burning situation, with blooming water flow, especially spray water flow not only can not spray to the burning wood, more can not enter the flame inside. The water is evaporated in the outer zone of the flame or swept away by the strong upward flow of air and has practically no effect on the burning process.

In all other cases, the use of bloom water streams and spray water is effective both in fighting fires by the capacity method and in fighting fires on the surface of combustible materials. The surface area of the blooming water stream in contact with the flame is robust. And its flight rate is slow, so the phase effect has long, while the spray water makes the flame heat dissipation conditions more prominent.