There is more to fire than just the emission of heat and light.
Fire, simply put, is a chemical process of combustion involving the oxidation of a fuel source at a high temperature. It releases energy and produces heat and light.
Flames are produced following the chemical reaction between oxygen and another gas.
Flames are intensified by increasing the rate of combustion.
Four elements, also known as the fire tetrahedron, must be present in order for a fire to exist.
These fire tetrahedron elements include:
- Oxygen.
- Heat.
- Fuel.
- Chemical reaction.
When you remove one of the four elements, the fire can then be extinguished.
Understanding the elements of fire is an essential component of firefighting education and suppression efforts.
The stages of fire
There are four stages of fire, including:
- Ignition: At this stage, a fire extinguisher can control the fire.
- Growth: Additional fuel ignites, causing the size of the fire to increase.
- Fully developed: This is when temperatures reach their peak, causing damage.
- Burnout: The fire gets less intense.
And in order to select the right type of extinguisher to put out a fire, you must understand the different classes of fires.
Classifying fire
Fires are classified into five groups, including:
- Class A fires: consist of ordinary combustibles, such as wood, paper, cloth, trash and plastics.
- Class B fires: are fueled by flammable or combustible liquids, such as grease, oil and gasoline.
- Class C fires: are also known as energized electrical fires. These fires involve electrical equipment, such as motors, transformers and appliances.
- Class D fires: comprise of combustible metal fires, involving metals such as potassium, sodium, aluminum and magnesium.
- Class K fires: involve cooking oils and greases, such as animal and vegetable fats.
Ultimately, having a basic understanding of what fire is and its types of classifications will lessen the chances of on-duty firefighter injuries and fatalities.
This article, originally published Jan. 26, 2017, has been updated with current information.
