We are well aware of the fact that oxygen is abundantly present in the air. Fire can be defined as a process of chemical combining substances with oxygen. Fire can produce bright light, heat, smoke, and burning. Sometimes Fire can be used for our benefit, like cooking, changing the temperature from low to high in cold places, etc, but the fire can cause hazards if it gets out of control.
The hazards may result in irreparable loss, involving the deaths of human beings. So, to save ourselves, others, and our environment from fire hazards, we must know about the fire types, to cope up the emergency situations.
There are three thongs that give rise to fire:
Oxygen is readily available in the air. As we human beings use oxygen to inhale similarly fire uses oxygen to expand.
The substances or the materials that catch fire are known as the fuel of fire. Paper, wood, plastic, metals, and a lot of other things are the fuel for the fire.
- Heat (ignition source):
We cannot burn a stove without burning a match stick. From this example we can clearly understand that there must be a source of ignition, resulting in fire.
These three things must be present to produce fire and if we want to control the fire, we can remove any one of them to avoid damages.
Types/classes of fire:
Now we are clearly familiar that what can happen if a fire incident takes place and how important it is to extinguish the fire. Extinguishing the fire becomes easy when we are familiar with the fuel of fire, due to this reason the fire is categorized into different classes. Mainly the fuel of fire is the basis of putting fire in classes. The fuel may be a liquid, solid, or gas.
Different types of fire extinguishers exist. The reason for classifying the fire is, to choose the right type of fire extinguishers that will work efficiently and effectively for extinguishing that fire. All fire extinguishers are not suitable for all types of fire. Let suppose if electric wires catch fire, we cannot use water-type fire extinguishers. Let us have a detailed look at types/classes of fire.
Class A fire:
When a solid material like paper, wood, or any cloth catches fire, it is a class A type of fire. These materials do not ignite on their own they always catch fire because of a flame from any other object.
Suitable fire extinguishers for class A fire:
Water fire extinguishers, foam, fire extinguishers, ABC dry chemical fire extinguishers, and wet chemical fire extinguishers should be used to extinguish such fire.
Class B fire:
The fire falls in the category of Class B if a liquid, like petrol, paint, or oil catches fire.
Suitable fire extinguishers for Class B fire:
Class C fire:
If the flammable gases like propane and butane catch fire, the fire belongs to Class C fire.
Suitable fire extinguishers for Class C fire:
We should use Dry powder fire extinguisher to extinguish this fire.
Class D fire:
If the fire burns any flammable metal, the fire is called a Class C type fire. Calcium, phosphorous, and many others are flammable metals.
Suitable fire extinguishers for Class D fire:
The dry special powder fire extinguisher will extinguish the Class C fire.
We have already mentioned that fire is classified according to the fuel. Electricity is not a fuel for the fire, it is a source of ignition that can cause a fire but it is not fuel for a fire, therefore, there is no Class E fire i.e. Class E is skipped.
Suitable fire extinguishers for electrical fire:
CO2 and dry powder type fire extinguishers are used for extinguishing an electrical fire.
Class F fire:
If cooking oils and fats catch fire, the fire is Class F fire.
Suitable fire extinguishers for Class F fire:
The wet chemical fire extinguisher is used to beat out the Class F fire.
Methods used by fire extinguishers to extinguish the fire:
Actually, fire extinguishers use different methods to extinguish the fire. We have already studied the fire triangle in the above section. If we remove either oxygen, fuel, or heat the fire will be extinguished. Different types of fire extinguishers are used to extinguish different types of fire by using three methods. Those methods are mentioned below:
One way to extinguish a fire is to eliminate the heat from the fire triangle this process or method is called “cooling”. Water fire extinguisher works on this mechanism to cut off class A fire.
As we human beings need food to eat, fire needs fuel to burn and expand. If we take out these fuels that are causing the fire to expand, the fire will be extinguished and the situation will be under control. Some fire extinguishers are designed on this mechanism to control the fire.
Oxygen is required to burn a fire and it is always present in the environment. So, if a fire incident takes place and we cut off the supply of oxygen from the environment to the fuel the fire will be extinguished. For example, when we cover a burning thing with a blanket, the oxygen supply to the fuel will be cut off and the fire will be eliminated. Some fire extinguishers work on this principle.