Running head: THE IMPORTANCE OF FLASHOVER RECOGNITION TRAINING 1 The Importance of Flashover Recognition Training Wesley Thornton University of Florida THE IMPORTANCE OF FLASHOVER RECOGNITION TRAINING 2 Abstract Firefighting is considered to be one of the most dangerous professions in the world and routinely exposes those involved in its line of work to both extremely high risk and high stressful situations. Unfortunately, several individuals associated with this profession have been seriously injured or killed while carrying out the duties that are involved with the job they love. While modern research and statistics have helped to correlate the relationship of cardiovascular emergencies in regards to both the high number of firefighter injuries and line of duty deaths (LODD) while participating in structural firefighting activities, they have also helped to unfortunately hide the importance of focusing on another major killer in the fire service which is the phenomenon known as flashover. The purpose of this paper is to help stress the importance of having a proper flashover recognition and prevention training program in place for today’s fire service in order to help reduce both the number of firefighter injuries and LODD’s, along with providing a detailed plan on how to create and implement such a plan. This paper will also discuss the events leading up to a flashover along with providing an in-depth analysis of today’s fire dynamics. THE IMPORTANCE OF FLASHOVER RECOGNITION TRAINING 3 The Importance of Flashover Recognition Training The dangers associated with structural firefighting activities have been well documented throughout the history of the fire service as hundreds of firefighters have been either seriously injured or killed while performing their duties on the fireground. A large majority of these injuries and deaths have either been directly or indirectly affected by the phenomenon known in the fire service as flashover. In order for fire administrators to truly appreciate the importance of incorporating flashover recognition training within their organization, they must first develop an understanding of not only what a flashover is along with the dangers associated with it, but must take the necessary time to research past incidents in which firefighters have been seriously injured or killed during one well. What is a Flashover? While there are several definitions in the fire service that can be used to describe flashover, the simplest way to describe this extremely dangerous phenomenon is the sudden full room involvement of flame. Flashover is not considered a stage of fire development, but is simply classified as a rapid transition between the growth and fully developed stage of a fire (Hartin, 2008). Flashover is a heat driven event that is caused by the heat transfer methods of convection and radiation as they work in conjunction to heat all substances in a room until they reach their ignition temperature and almost simultaneously combust at the same time. Flashover can be accelerated by thermal radiation feedback which occurs as the heat that is absorbed onto the walls and ceilings from the initial fire itself, begins to re-radiate downwards towards the contents in the room along with the suspended combustible gases that are present, causing them to simultaneously ignite. There are some researchers who consider flashover to be a transitional THE IMPORTANCE OF FLASHOVER RECOGNITION TRAINING 4 phase in the development of a compartment fire in which surfaces exposed to thermal radiation reach ignition temperature more or less simultaneously and fire spreads rapidly throughout the space resulting in full room involvement or total involvement of the compartment or enclosed area (Gorbett, 2007). Temperatures in a fire compartment can soar to well over 1200° F during a flashover which can cause a firefighters personal protective equipment (PPE) to burn within seconds. It is important for firefighters to realize that flashover is not time-dependent and may occur within seconds of an incipient stage fire or may never occur at all. Flashover times are dependent on multiple factors including the size of the fire compartment itself, the construction of that compartment, along with the fuel load that is available inside the same compartment as well. Regardless of which definition fire administrators choose to utilize in describing a flashover to their organization, the most important part of their presentation should focus on that flashover is a heat driven event and that the potential of a flashover occurring is always a possibility when participating in structural firefighting activities. Understanding Today’s Fire Dynamics and the Effect they have on a Flashover Fire dynamics is defined as the study of how chemistry, fire science, material science and the mechanical engineering disciplines of fluid mechanics and heat transfer interact to influence fire behavior (NIST, 2010). Today’s fire dynamics in residential structure fires are heavily influenced by both the buildings contents which usually consist of petroleum based products along with how today’s homes are being designed as well. The combination of these two factors alone have shortened the time of a flashover occurring in modern homes (mostly synthetic based contents) to under 5 minutes, where as it may have taken over 30 minutes to occur in a legacy style home (mostly natural product based contents). THE IMPORTANCE OF FLASHOVER RECOGNITION TRAINING 5 Heat release rates (HRR) are a measurement at which a fire releases energy or as some firefighters describe it, the power of the fire. The HRR's of those products involved directly and indirectly during a fire can a play a major role in several areas including the rate at which a fire develops, smoke production and speed, temperature ranges associated with the fire itself, along with the effects it will have on those involved in the fire as well. As we have leaned throughout our careers in the fire service, most objects have to be heated up in order to produce the gases that are needed to support combustion (pyrolysis). As a high HRR product continues to burn, it can cause other objects in the room to "off gas" at a much faster rate than a lower HRR product would, which can lead to exponential fire growth in that compartment. It is because of this exponential fire growth that the fire service has seen a direct correlation in the reduction of time in which a flashover may occur in today’s modern homes. In 2012, Underwriter Laboratories (UL) conducted multiple experiments that helped to show the effects synthetic based materials had on the fire dynamics found in today’s residential structures. The overall finding of UL’s fire testing is that the changes in the modern home create fires that reach flashover more than eight times faster than homes built 50 years ago (UL, 2012). While it is true that the overall physics of fire development have not changed over time, the structures however that there fires are occurring in today, especially the single family private dwelling have indeed changed tremendously. Today’s residential homes feature a multitude of changes in regards to how they were constructed 40 to 50 years ago. Some of these changes include the almost doubling in size of all single family dwellings being constructed today, along with a vast majority of these new homes being two story versus one story. The interior design of these larger homes have also changed from structures in the past as they now feature a more open floor plan look rather than the traditional compartmentation style that was popular prior to THE IMPORTANCE OF FLASHOVER RECOGNITION TRAINING 6 the 1990’s. Similar to the effects that petroleum based products have on today’s fire dynamics, this change in home size along with its trending open floor play layout can also play a major role on if and when a flashover may occur inside of these structures. It is important to understand that the larger the home being constructed, the more air that is not only going to be available to help accelerate fire growth, but that is going to help generate and even larger fire at the same time. The increase in homes with a second story allows a taller area in which a larger volume of smoke can accumulate above the fire itself, allowing that fire to continue to grow, whereas lower ceilings tends to keep the same level of smoke lower to the fire which can hinder its overall growth. All of these features remove compartmentation, add volume and can contribute to rapid smoke and fire spread (Kerber, 2012). Another key factor that has a tremendous impact on the fire dynamics that are found in today’s residential structure fires deals with the type of construction materials that are being used such as wall linings, different structural components, along with windows and interior doors to name a few. With the overall goal of construction contractors to build as many houses as fast and as cheap as possible combined with the increased use of environmentally sustainable building materials, have led to modern residential structures that do not hold up as long during a fire as did the legacy structures of 40 to 50 years ago did. As with the previous experiments, it was discovered that the use of new construction materials also leads to faster fire propagation, rapid changes in fire dynamics and shorter escape times for occupants and firefighters (UL, 2012) What are the Dangers Associated with a Flashover? In order for fire administrators to fully understand the dangers associated with a flashover, they must first understand how other firefighters have been either seriously injured or THE IMPORTANCE OF FLASHOVER RECOGNITION TRAINING 7 killed as a result of one occurring. During a 10-year period ranging from 2000-2009, 78 firefighter LODD’s were either directly or indirectly caused by a flashover with just over half of these deaths occurring in a one or two story private dwelling.