The Importance of Flashover Recognition Training Wesley

Running head: THE IMPORTANCE OF FLASHOVER RECOGNITION TRAINING

The Importance of Flashover Recognition Training

Wesley Thornton

University of Florida THE IMPORTANCE OF FLASHOVER RECOGNITION TRAINING

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

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

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. Once a flashover occurs, firefighting activities become more dangerous and it becomes increasingly difficult not only to search for occupants inside of that structure, but to extinguish the fire as well. Flashover can signal the beginning of the collapse stage of a fire due to fact that once a fire compartment flashes over, the structural members of the building begin to burn versus only the contents of that particular room that were burning prior to flashover occurring. It also important for firefighters to understand the human threshold for heat as it can help to stress the importance of not only wearing their full PPE during a fire, but can also help to show just how quick a firefighter can become seriously injured or killed once their gear becomes compromised during a flashover as well. Bare human skin begins to burn at 124° F and after only taking in a few breaths of air at

300° F an individual’s throat and lungs begin to sear causing them to die from asphyxiation.

During a flashover, temperatures are measured in the thousands of degrees-well beyond the limits of bunker gear (Flatley, 2005).

On March 21, 2003 Firefighter Oscar Armstrong of the Cincinnati Fire Department was killed during a flashover while attempting to deploy a dry handline with the assistance of two other firefighters through the front door of a private dwelling. The two members who with FF

Armstrong were fortunately assisted by other firefighters who were staged near the front porch and sustained only minor injuries. The total time between when FF Armstrong arrived on scene until when the flashover occurred was only four minutes, however due to the intense heat and other issues caused by the flashover, it took firefighters on scene 10 minutes to get the fire under control in order to locate his body for it to be transported to the hospital. On April 16, 2007 THE IMPORTANCE OF FLASHOVER RECOGNITION TRAINING

Firefighter Kyle Wilson of the Prince William County Fire Department was attempting a search of an upstairs bedroom with his officer in a nearly 6000 square-foot home, when a flashover occurred in the ceiling above him causing a tremendous spike in temperature within the room he was searching, eventually causing the room itself to flashover killing FF Wilson. FF Wilson’s company officer was able to make it to the door of the bedroom and then to the stairwell before the room itself flashed over.

Not only is it important for fire administrators to understand the dangers associated with a flashover while their members are operating on the fireground, it is equally as important that they understand that these same dangers exist during training evolutions that involve live fire structural burns as well. On July 31, 2002 Lieutenant John Mickel and Firefighter Dallas Begg of Osceola County Fire-Rescue, were killed during a flashover as they were performing a search for a rescue mannequin dressed in PPE during a live fire training evolution. Lieutenant Mickel and FF Begg entered the structure after a fire was set in a bedroom in which a combination of pallets and straw along with a foam mattress were used as the fuel load. As Lieutenant Mickel and FF Begg proceeded to search inside bedroom for the rescue mannequin, they were meet with thick black smoke, high heat, and zero visibility conditions. It was during these conditions in which one of the bedroom windows were broken out by a member of the outside vent team, causing a flashover within the bedroom and killing both firefighters.

How to Create and Implement a Flashover Recognition Training Program

Once fire administrators are able to develop an understanding of the dangers associated with a flashover, they must then focus their attention on why flashovers are continuing to catch firefighters of guard. While many in the fire service will contribute this to the recent THE IMPORTANCE OF FLASHOVER RECOGNITION TRAINING

9 advancements in firefighter PPE which is allowing their members to go further into super-heated environments than ever before, the main cause of firefighters seeing an increased exposure to flashover conditions lies within a departments training program as it relates to proper flashover recognition. Although the fire service as a whole is responding to less structure fires than in the past, the fires that we are responding to are not only more volatile and produce more heat than ever due to synthetic based materials, they are also causing structures to collapse faster once the fire reaches it structural members than ever before as well. It is imperative that fire administrators take the time to properly develop a flashover recognition training program that not only discusses the warning signs that are associated with a flashover, but that also discusses key factors such as point of no return, along with the techniques used to properly cool down a super- heated atmosphere. Discussing different flashover variables such as ceiling height and room size, along with how proper ventilation techniques can help to delay a flashover from occurring are also areas in which an organizations training program should focus on as well.

Developing a flashover recognition training program for your department should not be viewed as a task that has been mandated by the Fire Chief or another fire administrator, but should be viewed rather as an opportunity to create a program that will enhance the abilities of your personnel to popery interpret what a fire is telling them. The basis of proper flashover recognition training revolves around the four main signs of flashover which are a free burning fire, thick dark smoke, high heat build-up, and rollover. After identifying the four signs of a flashover, a quality training program would then involve breaking down each sign individually in order to go into more detail about the importance of that sign in relation to a flashover itself. THE IMPORTANCE OF FLASHOVER RECOGNITION TRAINING

With flashover being a heat driven event, the presence of a free burning fire is a must, as it produces the heat needed to cause pyrolysis of the contents within the fire compartment itself.

One of the biggest factors that contribute to the rate at which pyrolysis occurs within a fire compartment deals with the fire plume that is created during the initial stages of the free burning fire itself. The fire plume is a buoyant column of hot gases which are produced by the combustion of a particular fuel source in which it emits a vertical column of both flames and super-heated smoke. The HRR of these fuels play a major role in regards to how large and how fast a fire plume may develop and move throughout a compartment or building. An example of this would involve the type of fire plume that is created by the burning of synthetics or as we refer to them in the fire service "frozen gasoline", versus that of a fire plume that is created by some type of natural fibers that may be burning. The fire plume provides the radiant heat needed to help sustain the fire itself as well as the radiant heat needed to support pyrolysis as mentioned above.

Teaching firefighters how to properly read and interpret smoke is probably one of the most important parts of a flashover recognition training program. Smoke, as we know it in the fire service is considered to be unburnt fuel and if read properly can help prevent firefighters from being caught in a flashover. When discussing the importance of reading smoke as it relates to your training program, it is important to distinguish the difference between reading the volume of the smoke versus the velocity of the smoke, as well as the importance that both the density and color of the smoke have in relation to a potential flashover occurring. By itself, the volume of smoke which is being produced by a fire tells us very little, but can help to set the stage for understanding the amount of fuels that are off-gassing within a given space. It is important that firefighters realize that a hot clean burning fire is going to produce very little smoke which can THE IMPORTANCE OF FLASHOVER RECOGNITION TRAINING

11 prove to be deceiving for firefighters getting ready to enter a structure. The velocity of the smoke deals with how fast it is moving and can serve as an indicator of the amount of pressure that has built up inside the fire compartment as well. There are only two things that can cause smoke to pressurize within a building (heat or volume) and firefighters need to be able to distinguish between the two. Smoke velocity that is caused by heat will usually rise rapidly and slow gradually after it leaves the building, where as smoke velocity that is caused by restricted volume will slow immediately and balance with outside air. The is an extremely important part of reading smoke for every firefighter as fast moving turbulent smoke is a key indicator that a flashover may soon occur. The density or thickness of smoke is an indication of how much fuel is present in the smoke. As mentioned earlier, smoke is unburnt fuel which consists of fuel- airborne solids, aerosols, & gases that are capable of further burning. When reading smoke as a firefighter, it is important to understand that the thicker the smoke the more spectacular the flashover. The color associated with smoke allows firefighters the opportunity to understand several things about the fire itself such as what is burning, has the structure itself became involved in the fire, is water being applied to the fire, along with determining how quick a flashover may occur as well. It is important for firefighters to realize that the blacker the smoke the hotter the smoke is going to be. The term "black fire" is used in association with today’s fires that deal with the burning of synthetic materials all of which produce high HRR's. The smoke that is produced by these products can be described as super-heated thick black smoke that can cause the same exact damage to other contents inside the structure it may come in contact with just as direct flame impingement would. Flashover indicative smoke would include smoke that is both fast and dark and could be used by firefighters as a way of deterring the location of the main body of fire in a building. From a structural component side of a fire, THE IMPORTANCE OF FLASHOVER RECOGNITION TRAINING

12 unfinished wood gives off a distinctive brown colored smoke and could be an indication that the fire has reached either wall studs, floor joist, roof rafters/trusses or a combination of all three.

Firefighters who witness brown smoke coming from either the gable ends of roof or the eaves of floor seams, must understand that this may be a sign of impending collapse.

High heat build-up is another sign that firefighters must be aware of as it relates to flashover recognition. We must remember that flashover is a heat driven event which means that there is little chance of flashover occurring if there is no heat mixed within the smoke itself.

Firefighters entering a smoke-filled area should always make a mental note of the amount of heat they encounter in order for them to have a benchmark in relation to the heat they encounter as they continue to move forward throughout the structure. The lower firefighters are forced to crouch due to heat conditions as they move throughout a structure only increases the chances they are going to be caught in a flashover unless some type of intervention occurs.

Rollover, which is sporadic small flashes of flame mixed within smoke, is considered to be the last sign before flashover occurs. It is important for an organizations flashover recognition training program to stress that true rollover occurs only seconds before a fire compartment flashes over and should not be the first sign firefighters are looking for before applying water.

After your organization has identified the signs of flashover they wish to put into their training program, it is also important that they discuss some of the flashover variables that we may deal with on the firegound as well. The size of the room a fire is burning in along with the openings in that room have a direct impact on not only if a flashover will occur inside of that compartment, but effect how fast it may occur as well. A smaller room with minimal openings THE IMPORTANCE OF FLASHOVER RECOGNITION TRAINING

13 such as windows or doors may support flashover better than a larger room with multiple openings due to the fact that it will allow the heat to build up faster which can in turn heat up other contents in the room. The ceiling height of a room regardless of its size also plays a major factor on if a flashover may ever occur as well. A typical 8-foot ceiling found in a private dwelling will allow the fire plume to begin radiating heat onto other objects in a room, where as a 20 to 25 foot ceiling found in a commercial building may delay this from ever occurring at all.

Although a large majority of the fires that we encounter in the fire service occur in residential structures, it is important for firefighters to understand that residential fire experience cannot always be transferred to commercial buildings. Commercial buildings with large unenclosed spaces and ceilings 20-25 feet above the floor level can result in firefighters dangerously misinterpreting flashover size-up information. The presence of suspended ceilings or drop ceilings in commercial buildings have also led to multiple firefighter deaths and injuries as they have helped to hide both smoke and fire from crews operating on the inside of these buildings.

Commercial buildings with tall ceilings can also accumulate super-heated smoke, delaying the build-up of heat and smoke at the floor which could cause firefighters to walk into a building and become trapped by a flashover occurring at ceiling level.

Point of no return as it relates to flashover recognition training is used to describe the point a firefighter can reach from an exit should a flashover occur and hopefully still escape to safety. Today’s advancements in firefighter PPE are allowing firefighters to go both deeper and farther than ever before inside of structure fires, which combined with a lack of flashover recognition training, has helped to generate a recipe for disaster. This amazing technology is ultimately a double-edged sword; it acts as a protecting bubble, providing a false sense of security to the firefighter wearing the gear (Salzano, 2014). On average, a firefighter can travel 2 THE IMPORTANCE OF FLASHOVER RECOGNITION TRAINING

½ feet per second in full PPE without advancing a hoseline. With today’s flashover temperatures registering well over 1200° F due to the synthetic based materials found in today’s homes, a firefighter has the possibility of escaping a flashover should they be within 5 feet or less from an exit. Escape from a flashover is nearly impossible and recognizing the warning signs and knowing how to prevent them will do more to ensure your safety (Flatley, 2005).

While most tactical strategies on the fireground involve some type of ventilation in one form or another, most firefighters fail to realize how this basic tactic can help to delay a flashover from occurring as well. Venting the fire compartment allows super-heated gases to escape while replacing them with cooler air (venting to delay flashover). The fire compartment now has to build up enough heat to replace the lost heat faster than it can be replaced with cooler air (Kiurski, 2010). An example of this would be the coordination of ventilation between a fire attack team getting ready to enter a structure and the outside vent team as the vent one or two windows in the fire room itself if they are still intact. On the flip side of this, by closing a door to a fire compartment that is near pre-flashover conditions, the firefighter has now tremendously slowed down the air that was supplying the fire itself (not venting to delay flashover). By closing a door, you are also taking the imminent flashover out of the surrounding area so that other nearby rooms can be searched in a safer manner for a longer time (Kiurski, 2010). An example of this would include the forcible entry team pulling a door shut in which they may have just forced while the fire attack team is getting ready thus controlling the vent and limiting fresh air from entering the structure.

The importance of not only understanding when to apply water to an atmosphere in relation to the smoke conditions present in today’s fires, but understanding the most effective THE IMPORTANCE OF FLASHOVER RECOGNITION TRAINING

15 technique to properly apply that water is critical to both firefighter survival and preventing a flashover from occurring. Most firefighters who have been on the job for the last 20-30 years were more than likely taught early in their career that you never flow water on smoke itself.

While this tactic may have proven to be useful prior to the mass introduction of synthetic based materials, this same tactic if used today, will almost guarantee serious injury or death to the members of your department. The reason you can open the line on smoke in today’s fires is that the black-black smoke, a warning sign of flashover, is called “black fire” (Flatley, 2005).

Flowing adequate water either prior or during the signs of flashover can tremendously reduce the possibility of flashover from occurring while operating on the fireground. The simplest way of explaining the most effective method to your members in regards to applying water in order to prevent a flashover from occurring is to relate back to basic fire behavior principles. Firefighters are taught in rookie school that heat rises by convection during a fire and that the hottest gases present in a compartment fire are located at or near ceiling level. Once your firefighters are able to understand that flashover is a heat driven event, they can then begin to understand that in order to prevent a flashover from occurring they must properly apply as much water as possible into the upper atmosphere of a compartment fire. In order to do this, the most effective stream to use is either a straight stream from a fog nozzle or a solid stream from a smooth bore nozzle. By applying an adequate stream of water into the high heat layer of a compartment fire, firefighters are reducing the temperatures in that room which will in turn slow down the process of flashover.

Conclusion THE IMPORTANCE OF FLASHOVER RECOGNITION TRAINING

Although the risks associated with structural firefighting have been long accepted by many in the fire service, the need of fire administrators to both research and develop new training programs in an effort to reduce these risks is something that should continue to take place within every organization. The threat of today’s firefighters becoming caught in a flashover should be of major concern for all fire organizations due to multiple factors such as the continued use of synthetic materials, the manner in which structures are being built today along with the type of building materials being used, combined with the fact that many organizations have begun to focus on other areas that effect firefighter safety aside from the dangers involved in structural firefighting. 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 take the necessary time to research past incidents in which firefighters have been seriously injured or killed after a flashover has occurred as well.

THE IMPORTANCE OF FLASHOVER RECOGNITION TRAINING

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