By: Emergent Team
Understanding the four main stages of a fire is important for firefighting and fire prevention strategies. Each stage presents challenges and characteristics that require specific responses and safety measures. The bell curve of a fire, with the fully developed stage at its peak, visually represents the progression and intensity of a fire over time.
Ignition
The ignition stage, also known as the incipient stage, is the beginning of a fire. It occurs when a heat source comes into contact with a combustible material in the presence of oxygen, leading to a chemical reaction called combustion. This stage is typically small and localized, with the fire just starting to develop. Early detection and intervention are crucial during the ignition stage, as it is the best opportunity to extinguish the fire before it grows and spreads. Smoke detectors and fire alarms play a vital role in identifying fires at this early stage, allowing for prompt action.
Growth
During the growth stage, the fire begins to spread and intensify. The heat generated by the initial combustion causes nearby combustible materials to reach their ignition temperature, leading to a rapid increase in fire size and intensity. This stage is characterized by the development of a plume of hot gasses and flames that rise and spread horizontally. The growth stage can vary in duration depending on the availability of fuel, oxygen, and other environmental factors. Fire suppression efforts during this stage focus on controlling the spread of the fire and preventing it from reaching its fully developed stage.
Fully Developed
The fully developed stage represents the peak of a fire's intensity and is the top of the fire development bell curve. At this stage, the fire has consumed most of the available fuel and is producing the maximum amount of heat and flames. The temperature within the fire compartment reaches its highest point, often leading to structural damage and potential collapse. Firefighters face the greatest challenges during the fully developed stage, as the fire is at its most dangerous and destructive. Effective firefighting strategies and equipment are essential to manage and eventually control the fire at this stage.
Decay
The decay stage, also known as the burnout or smoldering stage, occurs when the fire diminishes due to a lack of available fuel or oxygen. The intensity of the flames and heat decreases, and the fire gradually burns out. While the fire may appear under control, hidden embers and hotspots can reignite if not properly extinguished. Firefighters must conduct thorough inspections and cooling operations during the decay stage to prevent rekindling and ensure the fire is completely out. Understanding the decay stage is important for post-fire safety and preventing secondary fires.
By understanding these stages and the fire development bell curve, we can better appreciate the complexity of fire behavior and the importance of timely and effective firefighting responses. Visualizing the progression of fire helps in planning and executing strategies to mitigate damage and protect lives and property.
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