Report: What Led To The Flashover Occurring?
What Led To the Flashover Occurring?
A flashover is probably the most significant thing to occur during a structure fire. As the fire burns, combustible gases are produced by the early stages of the fire growth process and the particles are not completely consumed. The gases rise, as discussed below, and form a superheated gas layer at the ceiling. In a typical structure fire the gas layer at the ceiling can reach temperatures near the 1,500 degree Fahrenheit mark. If enough oxygen is present in the fire compartment, flashover will occur causing everything in the room to combust almost simultaneously. The flashover is a critical part of the fire growth for two reasons. First, any living thing in the flashover room whether protected or not …show more content…
will survive and the chance of saving any victim is greatly reduced. Second reason is the fact that the flashover process increases the rate of combustion and it takes a greater amount of water to overtake the BTUs produced by the burning material. Once the flashover occurs the fire will begin to burn hotter and spread faster throughout the structure, which inhibits the search and rescue process, exposure protection, and easy containment of the fire.
Is a fire plume generated?
During a fire in a building a fire plume will be generated and begin to impinge on the ceiling, unless the ceiling is very high or the fire itself is very small in nature. As the fire plume rises, the hot gases hit the ceiling surface and make a 90 degree turn, spreading horizontally across the ceiling forming a ceiling jet. This is what allows sprinklers and smoke detectors to recognize the presence of fire. If the walls are too far away, then the temperature and the velocity of the ceiling jet will decay before it has a chance to reach the nearest wall and begin to bank down (Gann & Friedman, 2016).
Is there filling of the compartment by smoke? When a fire is present in a compartment without any openings for ventilation, two things will happen. First the ideal gas law comes into play because of the release of heat causes an increase in the pressure and gases inside the fire compartment. Second thing is if no opening is created by the pressure rupture, then the oxygen in the room will become oxygen depleted and the combustion process will cease. But in either case, as long as an opening does not exist, a hot layer of gas will form at the ceiling and begin to bank down filling the compartment with …show more content…
smoke.
What was the smoke flow from the compartment regarding the opening?
Well as the ceiling jet (hot gases moving horizontal across the ceiling) approached a wall, it began to bank downwards towards the floor. Continued burning within the structure increases the thickness of the smoke until it banks down and reaches the neutral plane. This smoke pressure is equalized throughout the room, causing it to bank to the less pressurized area below (Jones & Forney, 1992). This area is where the inside pressure equalized with the outside pressure entering the structure. A two-way flow begins to occur from the opening to the room. The inward flow is due to the air entrainment being sucked into the flames while the outward flow through the upper part of the opening is due to the added mass of combustible materials. This would only occur if the flame source were away from the opening, otherwise it would have just vented out the opening instead of traveling across the ceiling. Once the neutral plane is reached the smoke will travel into the next opening and fire spread will
continue.
What was the smoke movement? The smoke movement in the video consisted of filling the fire compartment and looking for a possible opening. Once the opening was found, first the open front door and second from the firefighter smashing the windows, the smoke traveled to areas of least resistance. The smoke had already reached the neutral zone but the sudden inward pressure caused the smoke to travel outward and up. The smoke will continue to move away from the seat of the fire until it becomes diluted by the outside air and is cooled both by the ambient air and the heat loss to the ceiling and walls.
A flashover is probably the most significant thing to occur during a structure fire. As the fire burns, combustible gases are produced by the early stages of the fire growth process and the particles are not completely consumed. The gases rise, as discussed below, and form a superheated gas layer at the ceiling. In a typical structure fire the gas layer at the ceiling can reach temperatures near the 1,500 degree Fahrenheit mark. If enough oxygen is present in the fire compartment, flashover will occur causing everything in the room to combust almost simultaneously. The flashover is a critical part of the fire growth for two reasons. First, any living thing in the flashover room whether protected or not …show more content…
will survive and the chance of saving any victim is greatly reduced. Second reason is the fact that the flashover process increases the rate of combustion and it takes a greater amount of water to overtake the BTUs produced by the burning material. Once the flashover occurs the fire will begin to burn hotter and spread faster throughout the structure, which inhibits the search and rescue process, exposure protection, and easy containment of the fire.
Is a fire plume generated?
During a fire in a building a fire plume will be generated and begin to impinge on the ceiling, unless the ceiling is very high or the fire itself is very small in nature. As the fire plume rises, the hot gases hit the ceiling surface and make a 90 degree turn, spreading horizontally across the ceiling forming a ceiling jet. This is what allows sprinklers and smoke detectors to recognize the presence of fire. If the walls are too far away, then the temperature and the velocity of the ceiling jet will decay before it has a chance to reach the nearest wall and begin to bank down (Gann & Friedman, 2016).
Is there filling of the compartment by smoke? When a fire is present in a compartment without any openings for ventilation, two things will happen. First the ideal gas law comes into play because of the release of heat causes an increase in the pressure and gases inside the fire compartment. Second thing is if no opening is created by the pressure rupture, then the oxygen in the room will become oxygen depleted and the combustion process will cease. But in either case, as long as an opening does not exist, a hot layer of gas will form at the ceiling and begin to bank down filling the compartment with …show more content…
smoke.
What was the smoke flow from the compartment regarding the opening?
Well as the ceiling jet (hot gases moving horizontal across the ceiling) approached a wall, it began to bank downwards towards the floor. Continued burning within the structure increases the thickness of the smoke until it banks down and reaches the neutral plane. This smoke pressure is equalized throughout the room, causing it to bank to the less pressurized area below (Jones & Forney, 1992). This area is where the inside pressure equalized with the outside pressure entering the structure. A two-way flow begins to occur from the opening to the room. The inward flow is due to the air entrainment being sucked into the flames while the outward flow through the upper part of the opening is due to the added mass of combustible materials. This would only occur if the flame source were away from the opening, otherwise it would have just vented out the opening instead of traveling across the ceiling. Once the neutral plane is reached the smoke will travel into the next opening and fire spread will
continue.
What was the smoke movement? The smoke movement in the video consisted of filling the fire compartment and looking for a possible opening. Once the opening was found, first the open front door and second from the firefighter smashing the windows, the smoke traveled to areas of least resistance. The smoke had already reached the neutral zone but the sudden inward pressure caused the smoke to travel outward and up. The smoke will continue to move away from the seat of the fire until it becomes diluted by the outside air and is cooled both by the ambient air and the heat loss to the ceiling and walls.