Classes of fire is a technique of categorizing the fire into different classes concerning the kind of material and fuel for burning. With the help of this categorization, we can identify the types of an extinguishing agent which can smother that class of fire.
All the fires are not the same. Fire starts ignition when there is some kind of materials that add fuel to the fire. For extinguishing the fire firstly, we need to know the kinds of fire and then we will use the extinguishing agent which can efficiently smother the fire. Different types of procedures and materials are used for smothering a specific class of fire.
On the basis of the ability of different extinguishing agents to smother the fire we divide the fire into the following classes:
Class A fire is the most common class of fire and we all are familiar with this class of fire. This class of fire contains many ordinary combustibles like wood, fabric, paper, plastic, rubber, and trash. Class A fire occurs when the ordinary combustible materials reached their ignition temperature and burning starts at that stage. The flames continue burning as long as there is an excess of oxygen because the supply of oxygen is the major cause of ignition. We can easily extinguish the fire. We can extinguish this class of fire with water but we need pressurized water for extinguishing it. A can of water that can spray water on the flames can be used for smothering it.
Class A fires are commonly put out with water or mono ammonium phosphate. We can also extinguish it with the help of a fire blanket or other materials or products.
Class A fire can occur in different locations including:
Class B fire includes flammable liquids like gasoline, acetone, kerosene, grease, paint, and alcohols. Flammable liquids catch on the fire and start burning easily at normal working temperature. Once the class B fire starts, it is very tough to control the fire and prevent its spreading. This class of fire involves nonmetal burning in a liquid state. This class of fire is a common hazard in industries that are dealing with lubricants and paints. We can extinguish this class of fire by simply cut off the supply of oxygen. We can extinguish class B fire by using Carbon dioxide extinguishers because when we fill CO2 gas in a cylinder at very high pressure it becomes cold and creates a barrier between the fire and oxygen cutting down the supply of oxygen to the fire and smother the fire in a very effective way.
There are certain locations that are at the risk of having fire hazards from this class of fire like:
The Source of class C fire involves burning gases. Most commonly used flammable gases include methane, butane, and propane that have the potential to cause an explosion. It is one of the most dangerous classes of fire and is very difficult to control. Gases add the fuel to the fire and fuel is one of the components of the fire triangle. So the locations that store burning gases must adopt some precautionary measures to avoid the fire hazards. Additionally, as flammable gases are heavier than air, they can travel a significant distance to an ignition source, which means the fire can spread rapidly. Flammable gases can cause an explosion and can lead to severe impact.
It is very difficult to extinguish class C fire. Before extinguishing the fire one should make sure that the supply of gas is first isolated because most of the fire extinguisher is ineffective to smother this class of fire. We can extinguish this class of fire by using Dry powder extinguisher.
C class fires can cause fire hazards in many buildings like:
Combustible metals can cause significant fire hazards as they are good conductors and transfer heat very rapidly. Certain metals like potassium, sodium, and aluminum. These metals burn when they come in contact with the fire and air. These metals even in the powdered form can cause a fire. We need great care to extinguish this fire because water, foam, and other extinguishing agents can excite the metals and cause massive burning.
Different metals require a different extinguishing agent for tackling the fire but the dry chemical powder can have the potential to extinguish the metal fire. This class of fire can cause fire hazards in industries where is a large amount of burning metal.
Electrical Fire can originate from energized electrical equipment. It can start ignition in wires, cables, circuit breakers, and other electrical components. An electrical fire can start because of overloading on the circuits when the supply of electricity is inadequate. Electrical fires are often fueled by motors, appliances, and electronic transformers.
It is very tricky to put off this type of fire. Firstly, we need to cut off the supply of electricity, and then we need to choose the ABC dry chemical fire extinguisher for spraying the powder over the fire. This powder will prevent the supply of oxygen to the flames and smother the fire efficiently.
Electrical fires are common in industries that deal with energy or make use of heavy electrically-powered equipment. However, electrical fires can occur on smaller scales in every kind of building like homes, offices, commercial locations, and so on.
Class F (Cooking Fats):
F Class Fires contains cooking oil and fats as a source of this class of fire. Cooking fires are fueled by a wide range of liquid cooking materials. Greases, cooking oils, vegetable fat, and animal fat are all fuel sources. It is very difficult to extinguish this class of fire because it involves high temperatures. Using water to extinguish a cooking fire can worse the fire and can cause huge fire damage to the building.
This is why we use a special fire extinguisher to extinguish the cooking fire. Wet chemical extinguishers contain a formula that cools the fire and prevents re-ignition.
T kind of fire is naturally of concern in the foodservice and restaurant industry. Many food-related industries are at risk of this fire.