Usually, a flashover occurs when all the surface and object suspended in the atmosphere have been heated to their blast-off temperature, and fire breaks out simultaneous over the surface. The first phase of flashovers usually results from the combustion of inflammable gasses that have amassed on the upper parts of a flame. At the early stages, fire progresses through, radiation, convection, and conduction. Within a small compartment, heat continues to accumulate at a higher rate than that which the cubicle can ventilate giving rise to a flashover.
In the video, the flashover occurred when all of the flammable materials in a room reach their ignition temperatures all together. Despite the fact that not all of the objects in the room had the same ignition temperatures, the heat must have been rising rapidly that the temperatures were all reached at spontaneously (Dunn & Jacoby/Storm Productions, 2006). The heat accumulated at the ceiling, exceeding its rate of absorption. This caused the heat to be compressed back down onto the lower level.
The fire plumed the ceiling which must have certainly been made of a material that is combustible. The house seems to have been quite old and was certainly not insulated as modern homes are. Modern doors and windows are more robust and equally energy proficient, their holding capacity for heat is therefore much better. Prior to the occurrence of a flashover, there was a growth stage that produced thick and dark smog. This was a head start for the eruption of a flashover any moment. Growth stages must exist regardless of whether it is obscured entirely or partially by thick smoke, furniture or a wall. The intense and dark smoke showed the fuels that were present were producing vapors which could burn when exposed to high heat.
A flashover does not depend on time some can occur in like the next two or so minutes after ignition, others may take quite a period of time. The time taken will majorly depend on the size of the compartment, its material, and quantity. These materials could not have been seen from outside the house, therefore, the firefighters had to make some assumptions and trust their instincts. When fighting a fire it is advisable to ventilate that building being put off. Unfortunately ventilating at the wrong time can not only be dear in controlling further spread of the blaze but also difficult in saving lives (Delmar Learning, 2008). From the video, one can see what happens when pure air comes into contact with the fire. Oxygen which is an element in the mixture of air supports combustion; it, therefore, facilitates the ignition of the fire.
Most people, specifically firefighters are confused about whether the abrupt influx of air creates a back draft due to a flashover or the explosive outpouring of smoke and fire or a flashover. A backdraft is when a fire unexpectedly explodes when introduced to oxygen after having consumed all oxygen initially. A back draft usually occurs after a window or any opening has been opened. The smoke flow from the compartment was as a result of the openings the firefighters created as they were trying to ventilate the structure (Flatley, C. 2005).
A flashover can be delayed by cooling the atmosphere with water from above the structure. This is usually done with a water-based fire extinguisher or a hose-line. Gasses are cooled by aiming the high heat layer with a stream of water under high pressure. Application of this methodology in the video world has helped in reducing the temperature and slows down the process of flashover. It worthwhile noting that the use of hose line does not imply the complete elimination of a flashover but rather delaying it.
Being able to control the movement of smoke in such a case in the video is essential for firefighting operations and safe rescue mission. Before firefighters can start putting off a fire they should first start with stabilizing the situation so as to prevent it from getting worse. From the video, the fire fighters seem to have been paying much attention to the flow of the smoke and fresh air. They might have done this so as to have a clear view of what they could rescue and also avoid inhaling the smoke. A large percentage of the gasses produced by a fire are toxic. Smoke is immediate by-product of fire it therefore extremely hot when created. Breathing in such superheated gasses may result in severe in the respiratory system.
Movement of smoke is a reliable indicator of the temperatures of the fire (Johansson & Van Hees, 2012). When temperatures are very high smoke produced flows quickly and forces its way through whatever opening. On the other hand, cool smoke moves gently and slowly. This was the case when the video began, suggesting that the fire was not that hot then. Virtually all materials produce a whitish smoke when heated at first. But as the materials dry out and disintegrate the color of the fume starts changing. This can be used to tell for how long thing have been subjected to the heat.
Delmar Learning. (2008). Firefighter’s handbook: Firefighting and emergency response.
Dunn, V., & Jacoby/Storm Productions. (2006). Flashover!
Flatley, C. (2005, March 5). FLASHOVER and BACKDRAFT: A primer – Fire engineering. Retrieved from http://www.fireengineering.com/articles/2005/03/flashover-and-backdraft-a-primer.html
Johansson, N., & Van Hees, P. (2012). A correlation for predicting smoke layer temperature in a room adjacent to a room involved in a pre-flashover fire. Fire and Materials, 38(2), 182-193. doi:10.1002/fam.2172