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Principle of fire extinguishing methods

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Principle of fire extinguishing methods topic focuses on Four ways to extinguish a fire, Fire spreads through 3 methods, an evacuation plan and many doubts may arise regarding this topic, but we will try to focus on how to extinguish by cooling, starvation and smothering. Employees and staff must know how to start a fire and spread and extinguish it.

It is no secret that fires can become huge catastrophes for industries, humanity and nature. The damage and scope of large fires can make things look hopeless to the naked eye. A large number of causes of fires within plants such as car accidents, gas leaks, electricity, hot work and many others, are quite dangerous for plants and people who are nearby.

Of course, becoming an expert in fire fighting and extinguishing is not as simple as reading a few lines about What Methods of Fire Extinguishing Are There. That is why it is so important that someone interested in this subject can be trained in the best way to provide all their knowledge to the area. In this way, you will help with the extinguishing of fires wherever you are and will also help with the forms of prevention in your locality or your workplace.

Know the Principle of Fire extinguishing methods

Principle of fire extinguishing methods

In both starting and sustaining a fire, various elements need to be present. When any of these are removed or their intensity is decreased, the fire can be controlled and eventually extinguished. There are four of these elements, and for each of them, there is a specific method of extinguishing fires. Specifically, they are combustion, an oxidant such as air, energy and a chemical chain reaction.

Fuel, oxygen, and heat activate the energy and the chain reaction is involved in a fire. As we mentioned, if one or more of the factors are eliminated, the fire can be extinguished.

Principle of fire extinguishing methods
Principle of fire extinguishing methods

 

As we know, fire is the result of combustion, which requires a combination of fuel and oxygen, as well as an ignition source. These days different methods can be used to extinguish fires. These generally involve the removal of heat by cooling the burning material, cutting fuel or adding chemicals.

Types of fire classes

Before using any fire extinguisher, it is very important to know the type of fire and what type of extinguisher we have available. Why is it important to know this? The answer is simple: if we use the wrong extinguisher we could be in serious danger.

‍Fire classes and extinguishers
5 classes of fire based on the material are:

A. Common solids fires
B. Flammable liquids and gases fires
C. Electrical equipment fires
D. For metals fires
K. Oils and fats fires

And there are 5 classes of fire extinguishers:

  1. Water
  2. Foam Agents
  3. Carbon Dioxide (CO2)
  4. Dry Chemical Powder
  5. Wet Chemical

Four ways to extinguish a fire

Principle of fire extinguishing methods

The fire tetrahedron identifies the four components necessary for burning to occur. Extinguishing a fire is largely about depriving the fire of one or more of these factors, so extinguishing methods can be classified based on the removal of these factors. The method of fire extinguishment is by cooling, smothering, starving, or inhibiting the combustion process.

Cooling method of extinguishing fire

Principle of fire extinguishing methods

It is the most common method to extinguish a fire. This seeks the extensive use of water as a cooling agent in solid material fires. Water vapour in contact with the fire covers the fire and also cuts off the oxygen supply. Although it is highly recommended that it not be used on fires involving oil or grease since water can allow these to spread.

The first method Principle of fire extinguishing methods is cooling, which is the most common. During combustion, heat or energy is generated, and when left in the environment, it ignites other fuels. By throwing substances on the fire that absorb that energy or that cool the materials, we achieve extinction. Water sprayed or mixed with certain additives is the most effective.

 

Principle of fire extinguishing methods

This Principle of fire extinguishing methods relies on cooling the fuel to a point where it does not produce enough steam to burn, and lowering the temperature depends on the application of the flow of water. For example, if the rate at which heat is generated by combustion is less than the rate at which it is lost from the burning material, combustion will not continue.

Principle of fire extinguishing methods
Principle of fire extinguishing methods

To extinguish a fire by cooling, the rate at which thermal energy is lost from the burning material must be increased by removing some of the thermal energy. This lowers the temperature of the burning mass, which reduces the rate of heat release. Eventually, the rate at which heat is lost from the fire may be greater than the rate of heat production, and the fire will die out.

Fire extinguishing methods starvation

Principle of fire extinguishing methods

Limit fuel by removing potential fuel from the vicinity of the fire, removing the fire from the mass of combustible materials, or dividing the burning material into smaller fires that can be more easily extinguished. This Principle of fire extinguishing methods seeks to eliminate the fuel supply by disconnecting electrical energy, isolating the flow of flammable liquids or extracting solid fuels such as wood or textiles.

For the fire to stay alive, there must be some type of fuel that serves to activate the flames. The first Principle of fire extinguishing methods is to eliminate the fire. If we manage to eliminate it from the area where the fire has occurred, it will end up extinguishing as it lacks the element that was feeding it.

Principle of fire extinguishing methods

For the extinction of fires, we will proceed with the cutting of liquids and gases to the area of the fire. It is recommended to know the operation of the valves that may exist to be able to close them quickly. Also, with the elimination of solids or all those containers that have liquids or gases inside.

As clearly indicated, it is when the fuel is removed from combustion, such as when the supply valve of the system that supplies fuel gas or a fuel liquid is closed. From the point of view of fire prevention, it is important to adopt measures such as the removal of waste and cleaning of the workplace, the substitution of raw materials for less flammable ones, the dilution of mixtures or natural or forced ventilation.

Smothering (Oxygen removal)

Principle of fire extinguishing methods

This Principle of fire extinguishing methods uses various agents to cut off the oxygen supply and thereby put out the fire. Foam, contained in some fire extinguishers, can help cool and insulate the fuel surface from the air, eliminating combustion and being able to resist wind and break the current.

Oxygen is an essential element for combustion. Therefore, the existence of this in a space feeds the flames. The second fire extinguishing method consists of using non-combustible materials to limit their contact with the air. Some examples are sand, foam, fire blankets, dust, lids, etc. Another possibility is to close the doors and windows to prevent more oxygen from entering.

Principle of fire extinguishing methods

Third, fire suppression can be achieved by carbon dioxide. Being heavier than air, we manage to displace it and replace it by being projected on the base of the flames. Water spray works similarly although it is less effective.

It is when the oxygen of combustion is removed, such as when a pan is covered with burning oil, when a fire is covered with earth or when a person whose clothes are burning is covered with a blanket. In industrial environments from the point of view of prevention, it translates into carrying out certain jobs in inert atmospheres, that is, with a low proportion of oxygen.

Inhibitor

Principle of fire extinguishing methods

Inhibit the chemical chain reaction by applying extinguishing media to the fire that inhibits the chemical chain reaction at the molecular level). The chain reaction is eliminated. The free radicals of the extinguishing agent react with the free radicals of the combustion in an endothermic reaction, which absorbs heat, and stops the chain reaction.

ABC Multipurpose Powder fire extinguishers are based on this principle. From the point of view of prevention, it translates into the addition of antioxidant substances to raw materials or the use of fire-retardant fabrics.

Free radicals are responsible for the rapid progression of fuel reactions. When those are neutralized, the reaction stops, so we also stop the spread of fire. Portable powder fire extinguishers are one of the methods used based on flames. Therefore, they are mandatory in most buildings.

Fire spreads through 3 methods

Principle of fire extinguishing methods

Fire propagation is known as the development of a fire when the four conditions necessary for it to occur exist: heat, fuel, oxidant and a chain reaction. The speed of spread will depend on these factors and it is important to act in time to avoid accidents with fatal consequences.

In places such as factories, offices, hospitals, schools and shopping centres it is important to try to control the spread, the goal is to prevent a fire from reaching different areas of the building and putting the lives of many people at risk. To achieve this, it is necessary to know how fire can spread and how to avoid this phenomenon.

Fire spread by radiation

Principle of fire extinguishing methods

It is a way of propagating energy through space by waves, heating solid and liquid bodies and passing through the air without changing its temperature. In forest fires, radiation is directly linked to the length of the flames. A form of thermal energy that is transferred in the form of electromagnetic waves, heating the solids and liquids (but not gases) that it finds in its path.”

Principle of fire extinguishing methods
Principle of fire extinguishing methods

For this reason, in this type of propagation, the rays travel directly and in all directions, so there is no need for any contact between the bodies. Furthermore, the heat rays travel regardless of the material in the intervening space.

Fire spread by convection

Principle of fire extinguishing methods

 

The heat is transported by the columns of hot air that rise, due to different densities that result from the temperature gradient in the area near the fire. The connective columns combined with the wind collaborate to disperse the incandescent fuel particles that fly inside, called ashes. Ashes can cause new foci in a fire. The air provides the oxygen for combustion.

Convective propagation refers to the movement of hot gases and vapours (smoke and hot air), which have a vertical rise through stairs and elevators. The bigger and hotter fire is, the faster it will spread and “the hotter it will rise.

This type of propagation is considered the most common cause of fire development, mainly inside buildings, since the heated gases and air pass between the structures until they reach the highest level of the buildings.

Fire spread by conduction

Principle of fire extinguishing methods

When heat is transmitted through the molecules of bodies without them moving. Unlike what happens with metals that transmit heat very quickly, wood is a poor conductor, so in surface or aerial forest fires, this form of heat transmission is the one that has the least influence. In underground wildfires, conduction is the most important mode of fire spread.

In the case of propagation by conduction, Cenapred points out that it consists of the movement of heat through a material, since “all elements are conductors of heat” even if they do so on a greater or lesser scale, and are in a state solid, liquid or gas.

Conductive elements have a heat transmission capacity that varies in each type of material, for example, cement walls, despite being considered poor conductors, can be damaged when there is a strong fire.

What should be included in an evacuation plan and how to prepare it?

Principle of fire extinguishing methods

Globally, in all businesses, companies, hospitals or any other building that houses people, there needs to be an evacuation plan for possible cases of risk such as fires, floods, earthquakes or others. This type of plan is designed exclusively for emergencies and contains a series of options that can be done in case of danger.

In some countries, there is an Occupational Risk Prevention Law that obliges companies to have an emergency plan with them at all times.  This indicates and establishes what should be provided to the staff in a general and periodic manner, information and guidance on occupational risk prevention, which includes having an evacuation plan.

Principle of fire extinguishing methods

This type of plan must be prepared by specialists within the prevention, health and safety at work sector since, within this type of document, it is precisely described how to act in an emergency, where people should be positioned, what spaces are safe and what routes must be taken to access them.

Likewise, the evacuation plan needs to have multiple options attached in case the emergency exits are blocked, in addition, to accurately marking the places where the emergency control equipment can be found: fire extinguishers, gas masks, and hammers to break windows, etc.

Passive and active measures

Principle of fire extinguishing methods

However, as part of prioritizing the safety and integrity of people before a fire occurs, it is necessary to carry out exercises to avoid fire risks inside buildings: passive and active.

 

Passive measures are known as all those in which the structure is involved, that is, everything related to the prevention of damage, such as evacuation routes for the population, which must be visible. Follow the OSHA standard for prevention.

Principle of fire extinguishing methods
Principle of fire extinguishing methods

On the other hand, active measures are all those fire extinguishing systems that periodically need to be maintained so that when they are used they are in good condition to suppress the fire. Both measures are essential but a fire risk assessment they are intended to reduce the danger of fire by describing the materials that the building has.

Reduce the probability of a fire breaking out.

Principle of fire extinguishing methods

In case the fire is already in action, the flames should not be allowed to spread, it is necessary to act effectively so that the damage is as little as possible. If the fire is already in position, there is a time necessary to control it and there are the following two phases:

  1. The time to discover where the fire is coming from to sound the alarm is key to avoiding a greater disaster.
  2. The instruments to put out the fire must work at the right time.
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