Posts Tagged ‘flashover’

A pre-arrival video of a July 23, 2013 residential fire posted on YouTube illustrates the impact of ventilation (making an entry opening) in advance of having a hoseline in place to initiate fire attack. The outcome of increased ventilation mirrors the full scale fire tests conducted by Underwriters Laboratories (UL) during their Horizontal Ventilation Study (see The Impact of Ventilation on Fire Behavior in Legacy and Contemporary Residential Construction or the On-Line Learning Module).

Residential Fire

63 seconds after the front door is opened, the fire transitions to a fully developed fire in the compartment on the Alpha/Bravo Corner of the building and the fire extends beyond the compartment initially involved and presents a significant thermal insult to the firefighters on the hoseline while they are waiting for water.

A More Fine Grained Look

Take a few minutes to go back through the video and examine the B-SAHF (Building, Smoke, Air Track, Heat, and Flame) Indicators, tactical actions, and transitions in fire behavior.

0:00 Flames are visible through a window on Side Bravo (Alpha Bravo/Corner), burning material is visible on the front porch, and moderate smoke is issuing from Side Alpha at low velocity.

0:30 Flames have diminished in the room on the Alpha/Bravo Corner.

1:18 An engine arrives and reports a “working fire”. At this point no flames are visible in the room on the Alpha/Bravo Corner, small amount of burning material on the front porch, moderate smoke is issuing at low velocity from Side Alpha and from window on Side Bravo

1:52 A firefighter kicks in the door on Side Alpha

2:02 The firefighter who opened the door, enters the building through the Door on Side Alpha alone.

2:08 Other members of the engine company are stretching a dry hoseline to Side Bravo.

2:15 Increased in flaming combustion becomes visible through the windows on Sides A and B (Alpha/Bravo Corner).

2:31 The firefighter exits through door on Side Alpha and flaming combustion is now visible in upper area of windows on Sides A and B (Alpha/Bravo Corner).

2:49 Flames completely fill the window on Side Alpha and increased flaming combustion is visible at the upper area of the window on Side Bravo. The engine company is now repositioning the dry hoseline to the front porch

2:55 The fire in the compartment on the Alpha/Bravo Corner is now fully developed, flames completely fill the window on Side Alpha and a majority of the window on Side Bravo. Flames also begin to exit the upper area of the door on Side Alpha.

3:07 Steam or vapors are visible from the turnout coat and helmet of the firefighter working in front of the window on Side Alpha (indicating significant heat flux resulting from the flames exiting the window)

3:25 Steam or vapors are visible from the turnout coat and helmet of the firefighter on the nozzle of the dry line positioned on the front porch (also indicating significant heat flux from flaming combustion from the door, window, and under the porch roof).

3:26 The hoseline on the front porch is charged and the firefighter on the nozzle that is positioned on the front porch begins water application through the front door.

Things to Think About

There are a number of lessons that can be drawn from this video, but from a ventilation and fire control perspective, consider the following:

• Limited discharge of smoke and flames (even when the fire has self-vented) may indicate a ventilation controlled fire.
• Ventilation controlled fires that have already self-vented will react quickly to additional ventilation.
• Control the door (before and after entry) until a hoseline is in place and ready to apply water on the fire
• Application of water into the fire compartment from the exterior prior to entry reduces heat release rate and buys additional time to advance the hoseline to the seat of the fire.
• Use of the reach of the stream from the nozzle reduces the thermal insult to firefighters and their personal protective equipment.

Also see Situational Awareness is Critical for another example of the importance of understanding practical fire dynamics and being able to apply this knowledge on the fireground.

Ed Hartin, MS, EFO, MIFireE, CFO

Amazing!

Thursday morning saw a sea change in perspectives on fire behavior in the United States! Over 2500 people were in the big room at FDIC to hear BC George Healey (FDNY), Dan Madryzkowski (NIST), Steve Kerber (UL), and LT John Ceriello (FDNY) talk about fire research conducted on Governors Island in New York.

This excellent presentation emphasized the importance of understanding fire behavior and the influence of flow path and provided several key tactical lessons, including:

• Importance of control, coordination, and communication between crews performing fire attack and those performing tactical ventilation
• The effectiveness of anti-ventilation such as closing the door (even partially) on slowing fire development
• Effectiveness of water quickly applied into the fire compartment (from any location, but in particular from the exterior) in slowing fire progression
• The demonstrated fact that flow path influences fire spread and not application of water. You can’t push fire with water applied into the fire compartment.
• Importance of cooling the hot smoke (fuel) in the upper layer

Several years ago, who would have thought that a presentation on fire dynamics and research would have drawn this number of people to a presentation at FDIC. Kudos to FDNY, NIST, and UL for their ongoing work in developing an improved understanding of fire dynamics and firefighter safety.

FAQ (Fire Attack Questions) Continued

I had the opportunity to visit with Captain Mike Sullivan with the Mississauga Ontario Fire Department while at FDIC and we are continuing our dialog with another series of questions related to the characteristics of water fog and its use of a fog pattern for self-protection when faced with rapid fire progression in a structure fire.

The next three questions deal with using a fog stream for protection. In the IFSTA Essentials of Firefighting 5th edition it states that “wide fog patterns can also protect firefighters from radiant heat”, however in the IFSTA Essentials of Firefighting 3rd edition it states “In the past, water curtain broken stream nozzles were commonly used for exposure protection. However, research has indicated that these nozzles are only effective if the water is sprayed directly against the exposure being protected”. This tells me that fog patterns cannot protect from radiant heat.

Another question for which the answer is “it depends”. Both statements are correct (in context). Water droplets reduce radiant heat by absorbing energy and scattering the radiant energy. The effectiveness of these mechanisms depends on droplet size, wavelength of the radiation, geometric dimensions of the water spray, and density of the fog pattern. To put this in context, firefighters use a water spray for protection when approaching a flammable gas fire. In this context, the high density of the spray in proximity of the nozzle is quite effective. In contrast, application of a water spray between a fire and exposure is likely to be much less dense, and thus less effective in protecting the exposure than simply applying water to the exposure to keep its temperature <100^o C.

In the past there was a belief (which some still believe) that if you find yourself in a bad situation in a house fire you can simply switch to a wide fog and it develops an “umbrella of protection from the heat and fire”. I believe this to be false. What I do think has happened in the past is that firefighters have found themselves in a room with extreme rollover or even had pockets of unburned gas igniting around them. When they used this technique they didn’t protect themselves with an umbrella of fog protection but they cooled the smoke layer and made the situation better.

This also is an interesting question, there are incidents where firefighters have opened the nozzle when caught in rapid fire progression and have survived (not necessarily uninjured), likely due to the cooling effects of the water spray. However, I would agree that this does not provide “an umbrella of protection” like a force field that provides complete protection. The benefit is likely by cooling of the hot gases above and potentially controlling some of the flaming combustion in the immediate area. However, as continuous application will likely not only cool the hot upper layer, but also generate a tremendous amount of steam on contact with compartment linings, the environment will not be tenable in the long term. However, this environment is likely more survivable than post-flashover, fully developed fire conditions.

Much the same as in driving or riding in fire apparatus, the best way to avoid death and injury in a crash is to not crash in the first place. If firefighters recognize worsening fire conditions, they should cool the upper layer to mitigate the hazards presented, if this is ineffective, withdrawing while continuing to cool the upper layer is an essential response.

My last comment on this; and this is where I am not really sure. If you are in a situation where you need to back out quickly, would it work to use a fog stream to push the heat away as you are reversing out of the structure? You would only do this for a short time while you retreat.

If you cannot put water on the fire to achieve control (shielded fire) or the heat release rate (HRR) of the fire exceeds the cooling capacity of your stream you are in a losing position. When faced with rapidly deteriorating thermal conditions, it is essential to cool the upper layer. It is important to note that cooling, not simply “pushing the heat away” is what needs to happen in this situation. This action reduces heat flux from both convective and radiant transfer. Adequate water must be applied to accomplish this task, as temperature increases so too does the water required. Long pulses provide a starting point, but the pulses need to be long enough to deliver the required water. If needed, flow could be continuous or near continuous while the crew withdraws. In much the same manner a crew working with a solid stream nozzle would operate the nozzle in a continuous or near continuous manner and rotate the stream to provide some cooling to the upper layer while withdrawing.

There are those who believe that you can use a fog stream to protect yourself in a house fire by pushing the heat away from you as you advance on the fire. I believe you can push heat away from you and it happens in 2 distinct ways,  the wide fog with the entrained air is literally pushing the heat away from you and you have now created high pressure in an area that was low pressure (typically you are near an open door) so you have effectively changed the flow path. Having said this, I feel the benefits are short lived. With this fog pattern you will also be creating a lot of steam which will continue expanding until it’s temperature reaches equilibrium with the rest of the fire compartment (expansion could be as high as 4000 times). With all this pushing and expansion you are now creating high pressure in an area down stream from you that had previously been a low pressure area. As we know, everything is trying to move from high to low pressure, now the low pressure area is directly behind the nozzle. Now you are in a situation where not only is the heat coming back behind the nozzle but there is an enormous amount of steam being created and heading your way. The confusion here is most likely with the techniques we use when practicing for gas fires, we do this outside where there is an endless amount of space to push the heat away (I read this part in a good article in Fire Engineering).

The impact of continuous application of a fog stream (or any stream for that matter) as you advance is dependent on a number of factors, principal among which are the flow path and where steam is produced (in the hot gas layer versus on contact with surfaces). Continuous application is likely to result in vaporization of a significant amount of water on contact with surfaces; this will result in addition of steam to the hot upper layer without corresponding contraction of the hot gases that results from vaporization of water while it is in the gases. Without ventilation in front of the fog stream (or any stream for that matter), this can result in a reduction in tenability. However, when ventilation in front of the stream is provided, a combination attack (using a fog pattern, straight, or solid stream) can be quite effective for fully developed fire conditions.

I was hoping you could elaborate on the term “painting”. It is defined as a “gentle application of water to cool without excess steam production”. The hard part as a firefighter is the word “gentle” as this word doesn’t register in firefighter lingo. I can see this during overhaul but was hoping you could elaborate.

The way that I typically explain the concept of “gentle” is using a fire in a small trash can or other incipient fire inside of a building. If you use a hoseline to extinguish this fire, it is unlikely that you will need a high flow rate or application of the stream with the bail of the nozzle fully open. It would be appropriate to simply open the nozzle slightly on a straight stream and apply a small amount of water to the burning fuel.

Surface cooling can be done using a vigorous application from a distance when faced with a well involved compartment. In this situation, the reach of the stream is appropriately used to extinguish the fire and cool hot surfaces from a distance to minimize thermal insult to firefighters while quickly achieving control. However when faced with hot and pyrolizing compartment linings or contents, it may be useful or necessary to cool these surfaces from closer proximity. In this case applying water with force will result in much of the water bouncing off the surfaces and ending up on the floor. Painting involves using a straight stream or narrow fog pattern with the nozzle gated back to provide a gentle application resulting in a thin layer of water on the hot surface. As you note, this is most commonly used during overhaul, but could be used anytime that there is a need to cool hot, pyrolizing, but unignited surfaces.

Next week Mike and I will conclude this series of FAQ with a look at pyrolysis and flow path.

This week’s questions focus on training firefighters to recognize, prevent, and if necessary react appropriately to flashover conditions. Casey Lindsay of the Garland, Texas Fire Department sent an e-mail to a number of fire behavior instructors regarding how they conduct “flashover training”

One of the challenges we face in discussing fire behavior training, particularly live fire training is the result of variations in terminology. Differences exist in the way that live fire training props are described and in fire control techniques. For this discussion, CFBT-US defines the type of prop pictured below as a “split level demo cell”. This terminology is derived from the original purpose of this design as conceived by the Swedish Fire Service in the 1980s. The split level cell is intended for initial fire behavior training focused on observation of fire development. As used in the United States (and some other parts of the world) it is described as a “flashover simulator” or “flashover chamber”. This provides a disconnect in context as this prop is not intended and does not subject the participants in training to flashover conditions, but simply provides an opportunity to observe fire development through the growth stage and recognize some potential cues of impending flashover.

Note: The prop illustrated above is a Split level cell at the Palm Beach County Fire Training Center.

Container based props can be configured in a variety of ways for both demonstration and fire attack training. Most commonly single compartment cells are single level or split level design. Multiple compartment cells are arranged in a variety of ways with containers placed in an “L”, “H” or other configuration.

Do you currently teach firefighters that “Penciling control techniques can be used to give firefighters additional time to escape a flashover”?

We define penciling as an intermittent application using a straight stream as compared to pulsing which uses a fog pattern or painting which is a gentle application of water to hot surfaces. We do not teach penciling, pulsing, or painting as a technique to give firefighters additional time to escape flashover. We use gas cooling (short or long pulses) and coordination of fire attack and ventilation to control the environment and prevent or reduce the potential for firefighters to encounter flashover. However, long pulses (or continuous application) while withdrawing is taught as a method of self-protection if fire conditions exceed the capability of the crew engaged in fire attack.

In response to Casey’s questions, Jim Hester, with the United States Air Force (USAF) presents an alternative perspective:

No! We do not teach penciling or 3D Fog attack anymore. We did temporarily after receiving our training as instructors in the flashover trainer. We gave the technique an honest look and conducted research using Paul Grimwood’s theories. We decided there are too many variables. For example; what works in a room and contents [fire] will not work in heavy fire conditions inside a commercial. The last thing we want is someone penciling any fire, inside any structure, that requires constant water application until the fire is darkened down. That’s what we teach.  Open the nozzle for as long as it takes to get knock down and then shut the nozzle down. [It is as] simple as that. If you take that approach, even in the flashover trainer you will alleviate confusion or misapplication of your fire stream.

While I have a considerably different perspective, Jim raises several good points. I agree that there are many variables related to fire conditions and room geometry. If firefighters are trained in lock step manner that short pulses are used to control the temperature overhead, there will definitely be a challenge in transitioning from the container to a residential fire and even more so when confronted with a commercial fire. However, if firefighters are introduced to the container as a laboratory where small fires are used to develop understanding of nozzle technique, rather than a reflection of real world conditions, this presents less of an issue.

As Jim describes, fire conditions requiring constant application in a combination attack with coordinated tactical ventilation, may not be controlled by short pulses. However, when cooling hot smoke on approach to a shielded fire, constant application of water will likely result in over application and less tenable conditions (too much water may not be as bad as too little, but it presents its own problems).

Most firefighters, even those that advocate continuous application, recognize that a small fire in a trash can or smoldering fire in a upholstered chair or bed does not require a high flow rate and can easily be controlled and extinguished with a small amount of water. On the other hand, a fully developed fire in a large commercial compartment cannot be controlled by a low flow handline. To some extent this defines the continuum of offensive fire attack, small fires easily controlled by direct application of a small amount of water and large fires that are difficult to control without high flow handlines (or multiple smaller handlines). There is not a single answer to what is the best application for offensive fire attack. Shielded fires require control of the environment (e.g., cooling of the hot upper layer) to permit approach and application of direct or combination attack. Fires that are not shielded present a simpler challenge as water can be brought to bear on the seat of the fire with less difficulty.

Nozzle operators must be trained to read conditions and select nozzle technique (pulsed application to cool hot gases versus penciling or painting to cool hot surfaces) and fire control methods (gas cooling, direct attack, indirect attack, or combination attack) based on an assessment of both the building and fire conditions.

What flashover warning signs do you cover during the classroom portion of flashover training?

We frame this discussion in terms of the B-SAHF (Building, Smoke, Air Track, Heat, and Flame) indicators used in reading the fire (generally, not just in relation to flashover).

Building: Flashover can occur in all types of buildings. Consider compartmentation, fuel type, and configuration, ventilation profile, and thermal properties of the structure. Anticipate potential for increased ventilation (without coordinated fire control) to result in flashover when the fire is burning in a ventilation controlled regime (most fires beyond the incipient stage are ventilation controlled). Note that these indicators are not all read during the incident, but are considered as part of knowing the buildings in your response area and assessing the building as part of size-up.

Smoke: Increasing volume, darkening color and thickness (optical density), lowing of the level of the hot gas layer.

Air Track: Strong bi-directional (in at the bottom and out at the top of an opening), turbulent smoke discharge at openings, pulsing air track (may be an indicator of ventilation induced flashover or backdraft), and any air track that shows air movement with increasing velocity and turbulence.

Heat: Pronounced heat signature from the exterior (thermal imager), darkened windows, hot surfaces, hot interior temperatures, observation of pyrolysis, and feeling a rapid increase in temperature while working inside (note that this may not provide sufficient warning in and of itself as it is a late indicator).

Flame: Ignition of gases escaping from the fire compartment, flames at the ceiling level of the compartment, isolated flames in the upper layer (strong indicator of a ventilation controlled fire) and rollover (a late indicator).

How do you incorporate the thermal imaging camera into your flashover class?

We do not teach a “flashover” class. We incorporate learning about flashover (a single fire behavior phenomena) in the context of comprehensive training in practical fire dynamics, fire control, and ventilation (inclusive of tactical ventilation and tactical anti-ventilation). Thermal imagers (TI) are used in a variety of ways beginning with observation of small scale models (live fire), observation of fire development (with and without the TI) and observation of the effects of fire control and ventilation.

Do you allow students to operate the nozzle in the flashover chamber?

We use a sequence of evolutions and in the first, the students are simply observers watching fire development and to a lesser extent the effects of water application by the instructor. In this evolution, the instructor limits nozzle use and predominantly sets conditions by controlling ventilation. If necessary the instructor will cool the upper layer to prevent flames from extending over the heads of the participants or to reduce the burning rate of the fuel to extend the evolution. Students practice nozzle technique (short and long pulses, painting, and penciling) outside in a non-fire environment prior to application in a live fire context. After the initial demonstration burn, students develop proficiency by practicing their nozzle technique in a live fire context.

When working in a single level cell rather than a split level cell (commonly, but inaccurately referred to as a “flashover chamber” or “flashover simulator”) we expand on development of students proficiency in nozzle technique by having them practice cooling the upper layer while advancing and importantly, while retreating. In addition, students practice door entry procedures that integrate a tactical size-up, door control, and cooling hot gases at the entry point.

Do you maintain two-in/two-out during flashover chamber classes?

We comply with the provisions of NFPA 1403 and provide for two-in/two-out by staffing a Rapid Intervention Crew/Company during all live fire training.

What is your fuel of choice for the 4×8 sheets (OSB, Particleboard or Masonite)?

We have used a variety of fuel types, but commonly use particle board. OSB tends to burn quickly, but can be used if this characteristic is recognized. We have also used a low density fiberboard product (with less glue) which performs reasonably well. The key with fuel is understanding its characteristics and using the minimum quantity of fuel that will provide sufficient context for the training to be conducted. I recommend that instructors conduct test burns (without students) when evaluating fuel packages that will be used in a specific burn building or purpose built prop (such as a demo or attack cell).

Do you have benches or seating in the flashover chamber?

No, firefighters are expected to be in the same position that they would on the fireground, kneeling or in a tripod position. When we work in a demo cell (“flashover chamber”) with benches, we keep the students on the floor.

Do you teach any flashover survival techniques, other than retreat/evacuate?

We focus first on staying out of trouble by controlling the environment. Second, we teach firefighters the skill of retreating while operating the hoseline (generally long pulses to control flames overhead). There are not really any options other than control the fire of leave the environment (quickly)! This is similar to James Hester’s answer of continuous flow, with a sweeping motion (long pulses can be applied in a sweeping manner, particularly in a large compartment). It is important to understand that a short pulse is extremely short (as fast as you can open the nozzle) and a long pulse is anything else (from several seconds to near continuous application, depending on conditions).

Refer to the series of CFBT Blog on Battle Drills for additional discussion developing proficiency in reaction to deteriorating conditions.

Additional Thoughts

Our perspective is that discussion of flashover should be framed in the context of comprehensive fire behavior training, rather than as a “special” topic. Practical fire dynamics must be integrated into all types of structural firefighting training, in particular: Hose Handling, Fire Control, and Tactical Ventilation (but the list goes on). When working with charged hoselines, take the time to practice good nozzle technique as well as moving forward and backward (do not simply stand up and flow water when performing hose evolutions). In fire control training (live fire or not), practice door control, tactical size-up, and door entry procedures. When training on the task activity of tactical ventilation (e.g., taking glass or cutting roof openings), make the decision process explicit and consider the critical elements of coordination and anticipated outcome of you actions.

FDIC

Plan on attending Wind Driven Fires in Private Dwellings at Fire Department Instructors Conference, Indianapolis, IN on Wednesday April 24, 2013 in Wabash 3. Representing Central Whidbey Island Fire & Rescue, Chief Ed Hartin will examine the application of NIST research on wind driven fires to fires in private dwellings. This workshop is a must if the wind blows where you fight fires!

Video of several incidents involving explosions during structural firefighting operations have been posted to YouTube in the last several weeks. Two of these videos, one from New Chicago, IN and the other from Olathe, KS involve residential fires. The other is of a commercial fire in Wichita, KS.

When a video shows some sort of spectacular fire behavior there is generally a great deal of speculation amongst the viewers about what happened. Was it a smoke (fire gas) explosion, backdraft, flashover, or did something else happen? Such speculation is useful if placed in the framework of the conditions required for these phenomena to occur and the Building, Smoke, Air Track, Heat, and Flame (B-SAHF) indicators that provide cues of to current fire conditions and potential fire behavior.

Occasionally, what happened is fairly obvious such as flashover resulting from increased ventilation under ventilation controlled conditions. However, the phenomena and its causal factors are often much more of a puzzle.

Download and print three copies of the B-SAHF Worksheet.

Residential Fire-Olathe, KS

Limited information was posted along with this pre-arrival video of a residential fire in Olathe, KS. The home was unoccupied when the fire occurred.

Watch the thirty seconds (0:30) of the video. First, describe what you observe in terms of the Building, Smoke, Air Track, Heat, and Flame Indicators; then answer the following five standard questions (based only on what you observe during the first thirty seconds of the video)?

1. What additional information would you like to have? How could you obtain it?
2. What stage(s) of development is the fire likely to be in (incipient, growth, fully developed, or decay)?
3. What burning regime is the fire in (fuel controlled or ventilation controlled)?
4. What conditions would you expect to find inside this building?
5. How would you expect the fire to develop over the next two to three minutes

Watch remainder of the video and consider the following questions:

1. Did fire conditions progress as you anticipated?
2. What changes in the B-SAHF indicators did you observe?
3. What may have caused the explosion (consider all of the possibilities)?
4. Were there any indications that may have given warning of this change in conditions?

Residential Fire-New Chicago, IN

Companies from New Chicago and Hobart were dispatched to a reported house fire at 402 Madison in New Chicago, IN on February 17, 2012.

Watch the thirty seconds (0:30) of the video. First, describe what you observe in terms of the Building, Smoke, Air Track, Heat, and Flame Indicators; then answer the following five standard questions (based only on what you observe during the first thirty seconds of the video)?

1. What additional information would you like to have? How could you obtain it?
2. What stage(s) of development is the fire likely to be in (incipient, growth, fully developed, or decay)?
3. What burning regime is the fire in (fuel controlled or ventilation controlled)?
4. What conditions would you expect to find inside this building?
5. How would you expect the fire to develop over the next two to three minutes

Watch remainder of the video and consider the following questions:

1. Did fire conditions progress as you anticipated?
2. What changes in the B-SAHF indicators did you observe?
3. What may have caused the explosion (consider all of the possibilities)?
4. Were there any indications that may have given warning of this change in conditions?

Commercial Fire-Wichita, KS

Wichita Fire Department on scene of a working building fire in large, non-combustible commercial building. Extreme heat and fire conditions cause an unknown cylinder to explode.

Keep in mind that gas cylinders and other closed containers can result in explosions during structural firefighting operations. Unlike backdraft and smoke explosion, the only clue may be building factors related to occupancy (and this may not be a good indicator when operating at a residential fire).

Wichita Fire Department on scene of a working building fire in a large metal structure. Extreme heat and fire conditions cause an unknown cylinder to explode. If you listen close, you can hear it vent before it goes off. Concussion actually cuts out my audio for just a couple seconds. No one was injured.

Video by Sean Black Photography http://seanblackphotography.smugmug.com/

Firefighter Safety

Potential for explosions related to extreme fire behavior such as backdraft and smoke explosion may be recognized based on assessment and understanding the B-SAHF (Building, Smoke, Air Track, Heat, and Flame) indicators. Other types of explosions such as those resulting from failure of closed containers (e.g., containing liquids or gases) may be a bit more difficult as this potential is likely to be present in most types of occupancies. However, commercial and industrial occupancies present greater risks.

Recognizing that even with sound experienced judgment, there may be undetected hazards on the fireground. Managing the risk requires developing a solid knowledge base and skills and operating within sound rules of engagement such as the IAFC Rules of Engagement for Structural Firefighting. However, considering the hazards presented by rapid fire progression and potential for changes in conditions following explosive events, I would add the following:

• Base your strategies and tactics on current and anticipated fire behavior and structural stability.
• Ensure that members correctly wear complete structural firefighting clothing and SCBA when working in the hazard zone and practice good air management. Buddy check before entry!
• Crews operating on the interior should have a hoseline or be directly supported by a crew with a hoseline. If conditions deteriorate, a hoseline allows self-protection and provides a defined egress path.
• Have well practiced battle drills for tactical withdrawal and abandoning the building (depending on conditions). See Battle Drill, Battle Drill Part 2, and Battle Drill Part 3.

Next…

My next post will address the impact of a closed door on tenability during a residential fire as the ninth tactical implication identified in the UL study on the Impact of Ventilation on Fire Behavior in Legacy and Contemporary Residential Construction.

Subsequent posts will come back to the Olathe, KS and New Chicago, IN residential fires to examine potential impacts on fire behavior and explosions that resulted during these incidents.

Ed Hartin, MS, EFO, MIFIreE, CFO

The eighth and tenth tactical implications identified in the Underwriters Laboratories study of the Impact of Ventilation on Fire Behavior in Legacy and Contemporary Residential Construction (Kerber, 2011) are the answer to the question, can you vent enough and the influence of pre-existing openings or openings caused by fire effects on the speed of progression to flashover.

The ninth implication; the effects of closed doors on tenability for victims and firefighters, will be addressed in the next post.

Photo Credit: Captain Jacob Brod, Pineville (NC) Fire Department

Kerber (2011) indicates that firefighters presume that if you create enough ventilation openings that the fire will return to a fuel controlled burning regime. I am not so sure that this is the case. Until fairly recently, the concept of burning regime and influence of increased ventilation on ventilation controlled fires was not well recognized in the US fire service. However, there has been a commonly held belief that increased ventilation will improve interior conditions and reduce the potential for extreme fire behavior phenomena such as flashover. In either case, the results of the experiments conducted by UL on the influence of horizontal ventilation cast considerable doubt on the ability to accomplish either of these outcomes using horizontal, natural ventilation.

The Experiments

In order to determine the impact of increased ventilation, Kerber (2011) compared changes in temperature with varied numbers and sizes of ventilation openings. The smallest ventilation opening in the experiments conducted in both the one and two story houses was when the door on Side A was used to provide the only opening. The largest number and size of ventilation openings was in the experiments where the front door and four windows were used (see Figures 1 and 3)

The area of ventilation openings in experiments conducted in the one-story house ranged from 1.77 m² (19.1 ft²) using the front door only to 9.51 m² (102.4 ft²) with the front door and four windows. In the two-story house the area of ventilation openings ranged from 1.77 m² (19.1 ft²) with front door only to 14.75 m² (158.8 ft²) using the front door and four windows.

The most dramatic comparison is between Experiments 1 and 2 where a single opening was used (front door) and Experiments 14 and 15 where five openings were used (door and four windows).

One Story House

Experiment 1 was conducted in the one-story house using the door on Side A as the only ventilation opening. The door was opened eight minutes after ignition (480 seconds). Experiment 14 was also conducted in the one-story house, but in this case the door on Side A and four windows were used as ventilation openings. Windows in the living room and bedrooms one, two, and three were opened sequentially immediately after the door was opened, providing more than five times the ventilation area as in Experiment 1 (door only).

Figure 1. Ventilation Openings in the One-Story House

In both Experiment 1 (door only) and Experiment 14 (door and four windows), increased ventilation resulted in transition to a fully developed fire in the compartment of origin (see Figure 2). In Experiment 1, a bi-directional air track developed at the door on Side A (flames out the top and air in the bottom). In Experiment 14, a bi-directional air track is visible at all ventilation openings, with flames visible from the door and window in the Living Room on Side A and flames visible through the window in Bedroom 3. No flames extended out the ventilation openings in Bedrooms 1, 2, and 3. The upper layer in Bedroom 3 is not deep, as such there is little smoke visible exiting the window, and it appears to be serving predominantly as an inlet. On the other hand, upper layer in Bedroom 2 is considerably deeper and a large volume of thick (optically dense) smoke is pushing from the window with moderate velocity. While a bi-directional air track is evident, this window is serving predominantly as an exhaust opening.

Figure 2. Fire Conditions at 600 seconds (10:00)

As illustrated in Figure 3, increased ventilation resulted in a increase in heat release rate and subsequent increase in temperature. It is important to note that the peak temperature in Experiment 14 (door and four windows) is more than 60% higher than in Experiment 1 (door only).

Figure 3. Living Room Temperature 0.30 m(1’) Above the Floor One-Story House

Note. Adapted from Impact of Ventilation on Fire Behavior in Legacy and Contemporary Residential Construction (p. 298), by Steve Kerber, 2011, Northbrook, IL: Underwriters Laboratories.

Based on observed conditions and temperature measurement within the one-story house, it is evident that increasing the ventilation from 1.77 m² (19.1 ft²) using the front door to 9.51 m² (102.4 ft²) with the front door and four windows did not return the fire to a fuel controlled burning regime and further, did not improve interior conditions.

It is important to note that these experiments were conducted without coordinated fire control operations in order to study the effects of ventilation on fire behavior. Conditions changed quickly in both experiments, but the speed with which the fire transitioned from decay to growth and reached flashover was dramatically more rapid with a larger ventilation area (i.e., door and four windows).

Two Story House

Experiment 2 was conducted in the two-story house using the door on Side A as the only ventilation opening. The door was opened ten minutes after ignition (600 seconds). Experiment 15 was also conducted in the two-story house, but in this case the door on Side A and four windows were used as ventilation openings. One window in the Living Room (Floor 1, Side A, below Bedroom 3) Den (Floor 1, Side C, below Bedroom 2) and two windows in the Family Room (Side C) were opened sequentially immediately after the door was opened, providing more than eight times the ventilation area as in Experiment 2 (door only).

Figure 4. Ventilation Openings in the Two-Story House

In both Experiment 2 (door only) and Experiment 15 (door and four windows), increased ventilation resulted in transition to a fully developed fire in the compartment of origin. Flames were seen from the family room windows in Experiment 15 (see Figure 5). However, in Experiment 2, no flames were visible on the exterior (due to the distance between the fire compartment and ventilation opening) and a bi-directional air track developed at the door on Side A (smoke out the top and air in the bottom). In Experiment 15, a bi-directional air track is visible at all ventilation openings, with flames visible from the windows in the family room on Side C. No flames extended out the ventilation openings on Side A or from the Den on Side C (see Figure 5). The upper layer is extremely deep (particularly considering the ceiling height of 16’ in the family room and foyer atrium. The velocity of smoke discharge from ventilation openings is moderate.

Figure 5. Fire Conditions at 780 seconds (13:00)

As illustrated in Figure 6, increased ventilation resulted in a increase in heat release rate and subsequent increase in temperature. It is important to note that the peak temperature in Experiment 15 (door and four windows) is approximately 50% higher than in Experiment 2 (door only).

Figure 6. Living Room Temperature 0.30 m(1’) Above the Floor One-Story House

Note. Adapted from Impact of Ventilation on Fire Behavior in Legacy and Contemporary Residential Construction (p. 299), by Steven Kerber, 2011, Northbrook, IL: Underwriters Laboratories.

Another Consideration

Comparison of these experiments answers the questions if increased horizontal ventilation would 1) return the fire to a fuel controlled state or 2) improve interior conditions. In a word, no, increased horizontal ventilation without concurrent fire control simply increased the heat release rate (sufficient for the fire to transition through flashover to a fully developed stage) in the involved compartment.

Examining thermal conditions in other areas of the building also provides an interesting perspective on these two sets of experiments. Figure 7 illustrates temperatures at 0.91 m (3’) during Experiment 1 (door only) and Experiment 14 (door and four windows) in the one-story house.

Figure 7. Temperatures at 0.91 m (3’) during Experiments 1 and 14

Note. Adapted from Impact of Ventilation on Fire Behavior in Legacy and Contemporary Residential Construction (p. 99, p. 162), by Steven Kerber, 2011, Northbrook, IL: Underwriters Laboratories.

Thermal conditions not only worsened in the fire compartment, but also along the flow path (for a more detailed discussion of flow path, see UL Tactical Implications Part 7) and in downstream compartments. Temperature in the hallway increased from a peak of just over 200^o C to approximately 900^o C when ventilation was increased by opening the four additional windows.

Unplanned Ventilation

Each of the experiments in this study were designed to examine the impact of tactical ventilation when building ventilation was limited to normal leakage and fire conditions are ventilation controlled (decay stage). In each of these experiments, increased ventilation resulted in a rapid increase in heat release rate and temperature. Even when ventilation was increased substantially (as in Experiments 14 and 15), it was not possible to return the fire to a fuel controlled burning regime.

It is also possible that a door or window will be left open by an exiting occupant or that the fire may cause window glazing to fail. The impact of these types of unplanned ventilation will have an effect on fire development. Creation of an opening prior to the fire reaching a ventilation controlled burning regime will potentially slow fire progression. However, on the flip side, providing an increased oxygen supply will allow the fire to continue to grow, potentially reaching a heat release rate that will result in flashover. If the opening is created after the fire is ventilation controlled, the results would be similar to those observed in each of these experiments. When the fire is ventilation controlled, increased ventilation results in a significant and dramatic increase in heat release rate and worsening of thermal conditions inside the building.

If the fire has self-ventilated or an opening has been created by an exiting occupant, the increased ventilation provided by creating further openings without concurrent fire control will result in a higher heat release rate than if the openings were not present and will likely result in rapid fire progression.

What’s Next?

I will be at UL the week after next and my next post will provide an update on UL’s latest research project examining the influence of vertical ventilation on fire behavior in legacy and contemporary residential construction.

Two tactical implications from the horizontal ventilation study remain to be examined in this series of posts: the impact of closed doors on tenability and the interesting question can you push fire with stream from a hoseline?

The last year has presented a challenge to maintaining frequency of posts to the CFBT Blog. However, I am renewing my commitment to post regularly and will be bringing back Reading the Fire, continuing examination of fundamental scientific concepts, and integration of fire control and ventilation tactics.

References

Kerber, S. (2011). Impact of ventilation on fire behavior in legacy and contemporary residential construction. Retrieved July 16, 2011 from http://www.ul.com/global/documents/offerings/industries/buildingmaterials/fireservice/ventilation/DHS%202008%20Grant%20Report%20Final.pdf

The fourth tactical implication identified in the Underwriters Laboratories study of the Impact of Ventilation on Fire Behavior in Legacy and Contemporary Residential Construction (Kerber, 2011) is that fire attack and (tactical) ventilation must be coordinated. This recommendation has been repeated in National Institute for Occupational Safety and Health (NIOSH) Death in the Line of Duty Reports for many years. In fact, most reports on firefighter fatalities related to rapid fire progression contain this recommendation.

Importance of Coordination

Coordination of (tactical) ventilation and fire attack as a tactical implication is closely related to the first two tactical implications identified in the UL study; potential changes in fire behavior based on stages of fire development, burning regime, and changes in ventilation profile that increase oxygen supplied to the fire.

If air is added to the fire and water is not applied in the appropriate time frame the fire gets larger and the hazards to firefighters increase. Examining the times to untenability provides the best case scenario of how coordinated the attack needs to be. Taking the average time for every experiment from the time of ventilation to the time of the onset of firefighter untenability conditions yields 100 seconds for the one-story house and 200 seconds for the two-story house. In many of the experiments from the onset of firefighter untenability until flashover was less than 10 seconds. These times should be treated as very conservative. If a vent location already exists because the homeowner left a window or door open then the fire is going to respond faster to additional ventilation openings because the temperatures in the house are going to be higher at the time of the additional openings (Kerber, 2011, p. 289-290)

The Impact of Ventilation on Fire Behavior in Legacy and Contemporary Residential Construction Underwriters Laboratories (UL) on-line course and report provide an example of firefighters are at risk when ventilation is performed prior to entry, fire attack is delayed, and other tactical operations such as primary search are initiated.

In UL’s hypothetical example, the firefighters make entry into the one-story house, search the living room (fire compartment), the kitchen, and dining room shortly after forcing the door and ventilating a large window in the fire compartment. Consider a somewhat different scenario, with the same fire conditions.

Companies respond to a residential fire with persons reported during the early morning hours. A truck and engine arrive almost simultaneously and while the engine lays a supply line from a nearby hydrant, the truck company forces entry, ventilates a window on Side A, and begins primary search (anticipating that the engine crew will be right behind them to attack the fire). The engine completes a forward lay and begins to stretch an attack line after the search team has made entry.

Figure 1. Timeline and Progression of Primary Search

Figure 2. View of the Living Room (Fire Compartment) from the Door on Side A

As illustrated in Figure 3, visible flaming combustion when the door is opened at 08:00 is limited to a small flame from the top of the couch just inside the door on Side A. However, in the 30 seconds that it takes for the search team to make entry, flaming combustion has resumed and flames are near or at the ceiling above the couch. The search team may estimate that they have time to complete a quick search of the bedrooms (likely location of the reported persons). However, fire development progresses to untenable conditions within a minute, trapping the crew on Side D of the house.

Figure 3. Fire Progression in the Living Room 00:08:00 to 00:10:00

As the search team completes primary search of Bedroom 2 and moves towards Bedroom 3 in the hallway, conditions have deteriorated to an untenable level. Figure 4 illustrates the change in temperature at the 3’ level in the Living Room (fire compartment). Shortly before the search team reached Bedroom 2, fire conditions in the living room began to change dramatically, with temperature at the 3’ level transitioning from ordinary to extreme, quickly becoming untenable in the living room, hallway and adjacent compartments. In addition to this significant change in temperature, flames (with temperatures higher than the gas temperature at the 3’ level) significantly increase radiant heat transfer (flux) to the surface of both fuel packages and firefighters protective equipment.

Figure 4. Temperature at the 3’ Level

Note: Figure 4 illustrates temperature conditions starting eight minutes after ignition. The fire previously progressed through incipient and growth stages before beginning to decay due to lack of ventilation.

Why the Dramatic Change in Conditions?

As discussed in UL Tactical Implications Part 1, Fires in the contemporary environment progress from ignition and incipient stage to growth, but often become ventilation controlled and begin to decay, rather than continuing to grow into a fully developed fire. This ventilation induced decay continues until the ventilation profile changes (e.g., window failure due to fire effects, opening a door for entry or egress, or intentional creation of ventilation openings by firefighters. When ventilation is increased, heat release rate again rises and temperature climbs with the fire potentially transitioning through flashover to the fully developed stage (see Figure 4 and 5).

Figure 5. Fire Development in a Compartment

Captain James Mendoza of the San Jose (CA) Fire Department and CFBT-US Lead Instructor demonstrates the influence of ventilation on fire development using a small scale prop developed by Dr. Stefan Svensson of the Swedish Civil Contingencies Agency.

The prop used in this demonstration is a small, single compartment with a limited ventilation opening on the right side (which in a full size building could be represented by normal building leakage or a compartment opening that is restricted such as a partially open door or window). The front wall of the prop is ceramic glass to permit direct observation of fire conditions within the compartment.

As you watch this demonstration, pay particular attention to how conditions change as the fire develops and then enters the decay stage. In addition, observe how quickly the fire returns to the growth stage and develops conditions that would be untenable after the window is opened at 12:17.

Download Doll’s House Plans (or Doll’s House Plans: Metric) for directions on how to construct a similar small scale prop.

Fire development and changes in conditions following ventilation in this demonstration mirror those seen in the full scale experiments conducted by UL. Increasing ventilation to a ventilation controlled fire, results in increased heat release rate and transition from decay to the growth stage of fire development.

The same phenomena can be observed under fireground conditions in the following video clip of a residential fire in Dolton, Illinois (this is a long video, watch the first several minutes to observe the changes in fire behavior).

It appears that the front door was open at the start of the video clip and the large picture window on Side A was ventilated at approximately 00:47. Fire conditions quickly transition to the growth stage with flames exiting the window and door, causing firefighters on an uncharged hoseline that had been advanced into Floor 1, to quickly withdraw.

As discussed in UL Tactical Implications: Part 1:

• Fires that have progressed beyond the incipient stage are likely to be ventilation controlled when the fire department arrives.
• Ventilation controlled fires may be in the growth, decay, or fully developed stage.
• Regardless of the stage of fire development, when a fire is ventilation controlled, increased ventilation will always result in increased HRR.
• Firefighters and fire officers must recognize that the ventilation profile can change (e.g., increasing ventilation) as a result of tactical action or fire effects on the building (e.g., window failure).
• Firefighters and fire officers must anticipate potential changes in fire behavior related to changes in the ventilation profile and ensure that fire attack and ventilation are closely coordinated.

Coordinated Tactical Operations

Understanding how fire behavior can be influenced by changes in ventilation is essential. But how can firefighters put this knowledge to use on the fireground and what exactly does coordination of tactical ventilation and fire attack really mean?

Tactical ventilation can be defined as the planned, systematic, and coordinated removal of hot smoke and fire gases and their replacement with fresh air. Each of the elements of this definition is important to safe and effective tactical operations.

Ventilation (both tactical and unplanned) not only removes hot smoke, but it also introduces fresh air which can have a significant effect on fire behavior.

Tactical ventilation must be planned; these two elements speak to the intentional nature of tactical ventilation. Tactics to change the ventilation profile must be intended to influence the fire environment or fire behavior in some way (e.g., raise the level of the upper layer to increase visibility and tenability). The ventilation plan must also consider the flow path (e.g., vent ahead of, not behind, the attack team; vent in the immediate area of the fire, not at a remote location).

Tactical ventilation must be systematic, exhaust openings should generally be made before inlet openings (particularly when working with positive pressure ventilation or when taking advantage of wind effects).

And as pointed out in the UL Study (Kerber, 2011), tactical ventilation must be coordinated. Coordination of ventilation and other tactical operations requires consideration of sequence and timing:

Sequence: Ventilation may be completed before, during, or after fire attack has been initiated. Sequence will likely depend on the stage of fire development, burning regime, time required to reach the fire.

If the fire is small and staffing is limited, it may be appropriate to control the fire and then effect ventilation (e.g., hydraulic ventilation performed by the attack team). This approach minimizes potential fire growth,

In general, when the fire is ventilation controlled (as those beyond the incipient stage are likely to be), ventilation should not be completed unless the attack line(s) can quickly apply water to the seat of the fire. In a small, single family dwelling this may mean that the attack team is on-air, the line is charged, and the entry door is unlocked or has been forced and is being controlled (held closed). In a larger building, this may mean that the attack line has entered the structure and is in position to move onto the fire floor or into the fire area.

The key questions that must be answered prior to implementing tactical ventilation are:

1. What influence will these ventilation tactics have on fire behavior?
2. Are charged and staffed attack line(s) in place?
3. Will the attack team(s) be able to quickly reach the fire?
4. How will this impact crews operating on the interior of the building?

Coordination requires clear, direct communication between companies or crews assigned to ventilation, fire attack, and other tactical functions that are or will be taking place inside the building.

Important: While not a tactical implication directly raised by the UL study, another important consideration is the hazard of working without or ahead of the hoseline. While a controversial topic in the US fire service (where truck company personnel generally work on the interior without a hoseline), searching with a hoseline provides a means of protection and a defined exit path. Staffing is another key element of the operational context. If you do not have enough personnel to control the fire and search; in most cases it is likely the best course of action to control the fire and ensure a safer operating environment for search operations.

What’s Next?

The next tactical implication identified in the UL study (Kerber, 2011) examines information that may be obtained by reading the air track at the entry point opening. This implication will be expanded with a broader discussion of air track indicators and how related hazards can be mitigated to improve firefighter safety.

References

Kerber, S. (2011). Impact of ventilation on fire behavior in legacy and contemporary residential construction. Retrieved July 16, 2011 from http://www.ul.com/global/documents/offerings/industries/buildingmaterials/fireservice/ventilation/DHS%202008%20Grant%20Report%20Final.pdf

There were multiple near miss incidents and injuries involving flashover during the month of December. These incidents point to the importance of understanding fire dynamics and reading the fire as part of initial size-up and ongoing dynamic risk assessment. Each member operating on the fireground must maintain a high level of situational awareness and communicate key fire behavior indicators and potential for extreme fire behavior phenomena.

Flashover Disrupts Firefighters’ Rescue Effort

Firefighters attempting to rescue a victim from a burning Portsmouth (VA) house on Thursday were forced to abandon the rescue attempt and exit a window when a flashover occurred.

Firefighters first entered the home through the front door, but were repelled by flames. They then made entrance through the front bedroom windows when the flashover occurred. After escaping, firefighters tried to reenter through the back of the house, but they could not.

FireEngineering.com

Ottawa Firefighter Pulled From Burning Basement

“An Ottawa firefighter had to be rescued from a burning basement after he was caught in a possible flashover yesterday afternoon. We don’t know what happened, and we haven’t had a chance yet to look into exactly what the details were, but we have a feeling that it might have been a flashover,” department spokesman Marc Messier said.

Firehouse.com

Columbus Firefighters Suffer Burns In Flashover

“Flames were coming up from the basement and out of the windows when crews arrived at the Dana Avenue house fire. There was a flashover, and fire crews quickly evacuated the duplex. Two firefighters were injured in the flashover, Battalion Chief David Whiting” said.

Nbc4i.com

Kansas City Firefighters Injured in Flashover

When they arrived, flames were coming from the first and second story of the house, firefighters said.

Kansas City, Mo., Fire Chief Smokey Dyer tells KMBC 9’s Justin Robinson what happened in a fire early Saturday that left three firefighters injured

Kansas City Fire Chief Smokey Dyer said crews went inside and started to go up the stairs, when conditions inside the house suddenly changed. He said it burned the fire hose and left the firefighters completely surrounded by flames. The firefighters sent out a mayday call for help.

“In the past 10 years, every significant firefighter injury that we have sustained in fire combat has been a result of a rapid change of conditions,” [emphasis added] Dyer said.

KMBC.com

Incidents such as these point to the need for continued emphasis on developing firefighters’ understanding of practical fire dynamics and effective strategies and tactics to control the fire environment and prevent, rather than react to occurrence of fire phenomena such as flashover.

Flashover is Just Flashover

In a recent discussion with a number of international colleagues, we were challenged to think about language, terminology, and precision when describing fire phenomena. While this is a more obvious challenge when working with firefighters, researchers, and scientists who have different first languages, it is also a day to day problem for firefighters with a common native language (e.g., English).

I have previously raised this question and proposed one approach as a starting point for classification of fire behavior phenomena based on outcome and the conditions required for the phenomena to occur (Language & Understanding: Extreme Fire Behavior and Extreme Fire Behavior: An Organizing Scheme).

Consider two recognized definitions for flashover:

• Stage of fire transition to a state of total surface involvement in a fire of combustible materials within an enclosure’ (ISO 13943, 2008, 4.156).
• A transitional 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 (NFPA 921-2007)

This transition is often assumed (and in many cases explicitly stated) to take place between the growth and fully developed stages. However, neither the ISO nor NFPA definition specifies this. In addition, while the NFPA definition indicates that this transition is extremely rapid (i.e., more or less simultaneously), the ISO definition does not describe the speed with which the transition to total surface involvement occurs.

In some respects, flashover is always a transition between the growth and fully developed stage (as increasing heat release rate is necessary). However, this may be a bit misleading. In the modern fire environment a compartment fire may follow an alternate path, often transitioning from growth to decay prior to flashover due to limited ventilation as illustrated in Figure 1.

Figure 1. Fire Development in a Compartment

As illustrated in Figure 1, the traditional fire development curve shows fire progressing neatly through incipient and growth stages, with occurrence of flashover resulting in transition to the fully developed stage and then decay as fuel is consumed.

The path of fire development is often quite different in the modern fire environment. The nature of common building contents provides a rapid increase in heat release rate (HRR) and corresponding oxygen consumption, resulting in the fire becoming ventilation controlled. With heat release limited by ventilation, the fire begins to decay (HRR and temperature are reduced). Uninterrupted this may cause the fire to self-extinguish. However, should an opening be created (as a result of window failure due to fire effects or opening of a door), the fire re-enters the growth stage and transitions through flashover to the fully developed stage. This is sometimes described as ventilation induced flashover (but in some respects, flashover is simply flashover).

In a spirited debate, some of my international colleagues have stated that “all flashover is ventilation induced” as ventilation is necessary to develop sufficient HRR for flashover to occur. Others have said that “flashover is temperature driven” as sufficient upper layer temperature is required. None have specifically said that flashover is a fuel dependent phenomenon, but this is true as well (given that the fuel that is burning must have sufficient energy and heat release rate for flashover to occur). In addition, flashover is dependent on compartment size and configuration, as a given fire will reach flashover in one compartment (generally a smaller one) and not in another). So, what’s the answer? It Depends!

This really boils down to being able to recognize what is important for firefighters to understand about fire development and flashover (as well as other extreme (i.e., extremely rapid changes in) fire behavior.

What We Know and Why It Matters

There are a number of things that we know about compartment fire behavior that are significant when considering how and why flashover occurs:

• Fire behavior is completely predictable if you have the necessary information and the time to analyze it (but on the fireground you seldom do). Predicting fire behavior is really saying: This is what I think is likely to happen.
• Changes in the built environment have influenced fire development (but there are a number of variables that may vary from nation to nation). In the US, modern building contents have increased heat of combustion and heat release rate, resulting in more rapid fire development than in the past.
• If ventilation is adequate, the typical room (e.g., bedroom, living room, family room) has well in excess of the amount of fuel (both in heat of combustion and peak heat release rate) to allow a fire to progress to flashover.
• Smoke is fuel. This is not dependent on the size or occupancy of the building. Smoke always presents a potential flammability hazard and as the concentration of fuel and energy in the smoke increases (think temperature, even though this is not the same as energy), the hazard increases.
• When a compartment fire becomes ventilation controlled, pyrolysis continues, adding additional gas phase fuel to the smoke in the upper layer.
• Building configuration and ventilation profile has a significant impact on fire development. However, despite increased compartment size and open floor plans, fires in modern single family dwellings are likely to be ventilation controlled when the fire department arrives.
• Increasing the air supplied to a ventilation controlled fire will result in an increased heat release rate (unless you immediately put the fire out) and this can occur quickly. Where you ventilate in relation to the fire, the existing heat release rate, and energy in the upper layer will all influence how quickly these changes occur.
• Creating an opening for entry is ventilation! This change in the ventilation profile often influences development of ventilation controlled fires by increasing air supply and providing a flow path for fire travel from the current area of involvement to the entry point (watch for a bi-directional air track with air in at the bottom and smoke out at the top of the opening).
• Adding additional openings will further increase the HRR and speed fire growth (unless you put the fire out). This is true even if the openings are near the seat of the fire.
• It is unlikely that you can tactically create sufficient ventilation to return a ventilation controlled fire to a fuel controlled burning regime (meaning that as you continue to increase ventilation, HRR will continue to rise). This does not mean that ventilation is bad as you may influence fire spread and the level of the upper layer, but recognize that the fire will get larger (increased HRR).
• Wind can have a significant influence on fire behavior. Consider wind direction, velocity, and how fire behavior (e.g., HRR, flow path) may change if the ventilation profile changes.

Given what we know, how should this inform our choice of strategies and tactics? Remember that strategies and tactics are context dependent. If you arrive with a single resource and two firefighters, your capabilities are different than if you arrive with six resources and 24 firefighters. Resources change some of your tactical options and the potential for concurrent operations. However, resources and their capability do not change the chemistry and physics of fire dynamics. It is important to recognize potential fire behavior, the scope and magnitude of the problems presented by the incident and the capabilities of the resources at hand.

Recognize that there are no simple answers to the questions of how much risk is too much and what actions are appropriate in a given circumstances. That said the following are steps you can take to reduce the potential of being caught or trapped by rapid fire progress:

• Recognize the indicators of flashover potential and communicate these observations to the members of your crew. Company officers (crew/team leaders) should communicate observation of flashover indicators to their immediate supervisor (e.g., Command, Division or Group Supervisor).
• Ensure that fire attack (or any other operation that involves working inside a burning building) and tactical ventilation is coordinated. In more explicit terms this means that ventilation occurs when companies or crews assigned to fire attack can quickly put water on the fire (not when they are ready to call for water or are simply ready to enter the building).
• Ensure that you are working on a hoseline (or are protected by one) if you are working in a smoke filled environment. Without a charged hoseline you have no defense (you cannot outrun flashover or other rapid fire development phenomena).
• Take positive actions to reduce the threat. If there are hot gases overhead, cool them. If you can put water directly on the fire, do it. If you put the fire out, things will generally improve! When you can control the fire ventilate to remove the smoke and remove the hazard.
• Consider the effects of wind on potential fire behavior. Consider exterior attack and avoid advancing lines in the potential flow path when the potential for wind driven fire conditions exits. Use caution when entering from the windward side and control inlet openings (or provide adequate exhaust).

Clearly understand when you are taking a reasonable and calculated risk and when you are gambling. Think about this before you are engaged in a firefight. Make it a conscious decision and not simply a default choice. Field Marshal Erwin Rommel made this distinction between taking risks and gambling: “With a risk, if it doesn’t work, you have the means to recover from it. With a gamble, if it doesn’t work you do not. Normally, to succeed you must take risks. On occasion you have to make a gamble” (Clancy, 1997, p. 152).

What’s Next?

My next post will dig into the findings and tactical implications of the recently released research results and on-line training program from Underwriters Laboratories (UL): Impact of Ventilation on Fire Behavior in Legacy and Contemporary Residential Construction.

This training program is of critical importance to anyone fighting fires in today’s buildings. All firefighters and fire officers should complete this training program before the end of January 2011! Take the time and get your head around the implications of this research on what we do on the fireground. This takes a bit of effort as we need to question our assumptions and standard practices, but the outcome is worth the work.

Be a student of our craft, be safe and look out for the firefighters and fire officer that work with you. Have a great New Year!

References

Clancy, T. Into the storm: A study in command. New York: G. F. Putnam & Sons

This post continues examination of the incident that took the life of Firefighter Brian Carey and seriously injured Firefighter Kara Kopas on the evening of March 30, 2010  while they were operating a hoseline in support of primary search in a small, one-story, wood frame dwelling with an attached garage at 17622 Lincoln Avenue in Homewood, Illinois.

This post focuses on firefighting operations, key fire behavior indicators, and firefighter rescue operations implemented after rapid fire progression that trapped Firefighters Carey and Kopas.

Firefighting Operations

After making initial assignments, the Incident Commander performed reconnaissance along Side Bravo to assess fire conditions. Fire conditions at around the time the Incident Commander performed this reconnaissance are illustrated in Figure 7. After completing recon of Side B, the Incident Commander returned to a fixed command position in the cab of E-534 (in order to monitor multiple radio frequencies).

Figure 7. Conditions Viewed from Side C during the Incident Commander’s Recon

Note: John Ratko Photo from NIOSH Death in the Line of Duty Report F2010-10.

Engine 1340 (E-1340) arrived and reported to Command for assignment. The five member crew of this company was split to assist T-1220 with vertical ventilation, horizontally ventilate through windows on Sides B and D, and to protect Exposures D and D2.

One member of E-1340 assisted T-1220 and the remaining members vented the kitchen windows on SidesD and B, while the E-1340 Officer stretched a 1-3/4” (45 mm) hoseline from E-534 to protect exposures on Side D. However, this line was not charged until signficantly later in the incident (see Figure 14). Figure 8 (a-c) illustrates changing conditions as horizontal ventilation is completed on Sides B and D.

Figure 8. Sequence of Changing Conditions Viewed from the A/B Corner

At 2105 Command reported that crews were conducting primary search and were beginning to vent.

Note the B-SAHF indicators visible from the A/B Corner in Figure 8a: Dark gray smoke from the door on Side A with the neutral plane at approximately 18” (0.25 m) above the floor. Velocity and turbulence are moderate and a bidirectional air track is evident at the doorway.

As the 2-1/2” (64 mm) handline reached the kitchen, flames were beginning to breach the openings in the Side C wall of the house and thick black smoke had banked down almost to floor level. As noted in Figure 3 (and subsequent floor plan illustrations), there were doors and windows between the house and addition in the Utility Room and Bedroom 2 . The Firefighter from E-534 had a problem with his protective hood and handed the nozzle off to Firefighter Carey and instructed him to open and close the bail of the nozzle quickly. After doing so, the Firefighter from E-534 retreated along the hoseline to the door on Side A to correct this problem (he is visible in the doorway in Figure 8c).

As E-1340 vents windows on Sides B (see Figure 8b) and D, the level of the neutral plane at the doorway on Side A lifts, but velocity and turbulence of smoke discharge increases. Work continues on establishing a vertical vent, but is hampered by smoke discharge from the door on Side A.

After horizontal ventilation of Sides B and D, velocity and turbulence of smoke discharge continues to increase and level of the upper layer drops to the floor as evidenced by the neutral plane at the door on Side A (see Figures 8b and 8c)

The photo in Figure 8c was taken just prior to the rapid fire progression that trapped Firefighters Carey & Kopas. The Firefighter from E-534 is visible in the doorway correcting a malfunction with his protective hood.

As T-1220B reached the hallway leading to the bedrroms, they felt a significant increase in temperature and visibility worsened. After searching Bedroom 2 and entering Bedroom 1 temperature contiued to increase and T-1220B observed flames rolling through the upper layer in the hallway leading from Bedroom 2 and the Bathroom. Note: NIOSH Death in the Line of Duty Report 2010-10 does not specify if T-1220B searched Bedroom 2, but this would be consistent with a left hand search pattern. They immedidately retreated to the Living Room looking for the hoseline leading to the door on Side A. As they did so, they yelled to the crew on the 2-1/2” (64 mm) handline to get out.

Extreme Fire Behavior

Firefighter Kopas felt a rapid increase in temperature as the upper layer ignited throughout the living room and the fire in this compartment transitioned to a fully developed stage. She yelled to Firefighter Carey, but received no response as she turned to follow the 2-1/2” (64 mm) hoseline back to the door on Side A. She made it to within approximately 4’ (1.2 m) of the front door when her protective clothing began to stick to melted carpet and she became stuck. T-1220B saw that she was trapped, reentered and pulled her out.

Figure 12. Position of the Crews as the Extreme Fire Behavior Phenomena Occurred

Note: It is unknown if T-1220B searched Bedroom 2 before entering Bedroom 1. However, this would be consistent with a left hand search pattern.

Figure 13. Conditions Viewed from the Alpha/Bravo Corner as the Extreme Fire Behavior Occured

Note: Warren Skalski Photo from NIOSH Death in the Line of Duty Report F2010-10.

Figure 14. Conditions Viewed from the Alpha/Delta Corner as the Extreme Fire Behavior Occured

Note: Warren Skalski Photo from NIOSH Death in the Line of Duty Report F2010-10.

Following the transition to fully developed fire conditions in the living room, the Incident Commander ordered T-1220 off the roof. As illustrated in Figure 14, the exposure protection line stretched by E-1340 was not charged until after Firefighter Carey was removed from the building.

Figure 15. Position of Search and Fire Control Crews after Rapid Fire Progress

Firefighter Rescue Operations

The Incident Commander and Firefighter from E-534 (who had retreated to the door due to a problem with his protective hood), pulled a second 1-3/4” (45 mm) line from E-534. T-1220B re-entered the house with this hoseline to locate Firefighter Carey.

While advancing into the living room, T-1220B discovered that E-534’s 2-1/2” (64 mm) handline. They controlled the fire in the living room using a direct attack on burning contents and advanced to the kitchen where they discovered Firefighter Carey entangled in the 2-1/2” (64 mm) handline. Firefighter Carey’s helmet and breathing apparatus facepiece were not in place.

T-1220B removed Firefighter Carey from the building where he received medical care from T-1145. A short time later, Firefighter Carey became apenic and pulseless. After the arrival of Ambulance 2101 (A-2101), Firefighter Carey was transported to Advocate South Suburban Hospital in Hazel Crest, IL where he was declared dead at 10:03 pm.

According to the autopsy report, Firefighter Carey had a carboxyhemoglobin (COHb) of 30% died from carbon monoxide poisoning. The NIOSH Death in the Line of Duty Report (2010) did not indicate if the medical examiner tested for the presence of hydrogen cyanide (HCN) or if thermal injuries were a contributing factor to Firefighter Carey’s death.

Timeline

Review the Homewood, Illinois Timeline (PDF format) to gain perspective of sequence and the relationship between tactical operations and fire behavior.

Contributing Factors

Firefighter injuries often result from a number of causal and contributing factors. NIOSH Report F2010-10 identified the following contributing factors in this incident that led to the death of Firefighter Brian Carey and serious injuries to Firefighter Kara Kopas.

• Well involved fire with trapped civilian upon arrival.
• Incomplete 360^o situational size-up
• Inadequate risk-versus-gain analysis
• Ineffective fire control tactics
• Failure to recognize, understand, and react to deteriorating conditions
• Uncoordinated ventilation and its effect on fire behavior
• Removal of self-contained breathing apparatus (SCBA) facepiece
• Inadequate command, control, and accountability
• Insufficient staffing

Questions

The following questions focus on fire behavior, influence of tactical operations, and related factors involved in this incident.

1. What type of extreme fire behavior phenomena occurred in this incident? Why do you think that this is the case (justify your answer)?
2. How did the conditions necessary for this extreme fire behavior event develop (address both the fuel and ventilation sides of the equation)?
3. What fire behavior indicators were present in the eight minutes between arrival of the first units and occurrence of the extreme fire behavior phenomena (organize your answer using Building, Smoke, Air Track, Heat, and Flame (B-SAHF) categories)? In particular, what changes in fire behavior indicators would have provided warning of impending rapid fire progression?
4. Did any of these indicators point to the potential for extreme fire behavior? If so, how? If not, how could the firefighters and officers operating at this incident have anticipated this potential?
5. What was the initiating event(s) that lead to the occurrence of the extreme fire behavior that killed Firefighter Carey and injured Firefighter Kopas?
6. How did building design and construction impact on fire behavior and tactical operations during this incident?
7. What action could have been taken to reduce the potential for extreme fire behavior and maintain tenable conditions during primary search operations?
8. How would you change, expand, or refine the list of contributing factors identified by the NIOSH investigators?

My last post, Hazards Above, provided a brief overview of three incidents involving extreme fire behavior in the attic or truss loft void spaces of wood frame dwellings. This post will examine the similarities and differences between these lessons and identify several important considerations when dealing with fires occurring in or extending to void spaces. At the conclusion of Hazards Above, I posed five questions:

1. What is similar about these incidents and what is different?
2. Based on the limited information currently available, what phenomena do you think occurred in each of the cases? What leads you to this conclusion?
3. What indicators might have pointed to the potential for extreme fire behavior in each of these incidents?
4. How might building construction have influenced fire dynamics and potential for extreme fire behavior in these incidents?
5. What hazards are presented by fires in attics/truss lofts and what tactics may be safe and effective to mitigate those hazards?

Similarities and Differences

The most obvious similarities between these incidents was that the buildings were of wood frame construction, the fire involved or extended to an attic or truss loft void space, and that some type of extreme fire behavior occurred. In two of the incidents firefighters were seriously injured, while in the other firefighters escaped unharmed.

Given the limited information available from news reports and photos taken after the occurrence of the extreme fire behavior events, it is not possible to definitively identify what types of phenomena were involved in these three incidents. However, it is interesting to speculate and consider what conditions and phenomena could have been involved. It might be useful to examine each of these incidents individually and then to return to examine fire behavior indicators, construction, and hazards presented by these types of incidents.

Minneapolis, MN

In the Minneapolis incident the fire occurred in an older home with legacy construction and relatively small void spaces behind the knee walls and above the ceiling on Floor 3. The triggering event for the occurrence of extreme fire behavior is reported to be opening one of the knee walls on Floor 3. As illustrated in Figure 1, the fire appeared to transition quickly to a growth stage fire (evidenced by the dark smoke and bi-directional air track from the windows on Floor 3 Side A. However blast effects on the structure are not visible in the photo and were not reported.

Figure 1. Minneapolis MN Incident: Conditions on Side A

Note: Photo by Steve Skar

Potential Influencing Factors: While detail on this specific incident is limited, it is likely that the fire burning behind the knee wall was ventilation controlled and increased ventilation resulting from opening the void space resulted in an increase in heat release rate (HRR). Potential exists for any compartment fire that progresses beyond the incipient stage to become ventilation controlled. This is particularly true when the fire is burning in a void space.

Extreme Fire Behavior: While statements by the fire department indicate that opening the knee wall resulted in occurrence of flashover, this is only one possibility. As discussed in The Hazard of Ventilation Controlled Fires and Fuel and Ventilation, increasing ventilation to a ventilation controlled fire will result in increased HRR. Increased HRR can result in a backdraft (if sufficient concentration of gas phase fuel is present), a vent induced flashover, or simply fire gas ignition (such as rollover or a flash fire) without transition to a fully developed fire.

Harrisonburg, VA

The Harrisonburg incident involved extreme fire behavior in Exposure D (not the original fire unit). The extreme fire behavior occurred after members had opened the ceiling to check for extension. However, this may or may not have been the precipitating event. As illustrated in Figure 2, as members prepare to exit from the windows on Floor 3 , Side C, flames are visible on the exterior at the gable, but it appears that combustion is limited to the vinyl siding and soffit covering. There are no indicators of a significant fire in Exposure D at the time that the photo was taken. However, it is important to remember that this is a snapshot of conditions at one point in time from a single perspective.

Figure 2. Harrisonburg, VA Incident: Conditions on Side C

Note: Photo by Allen Litten

Potential Influencing Factors: The truss loft was likely divided between units by a 1 hour fire separation (generally constructed of gypsum board over the wood trusses). While providing a limited barrier to fire and smoke spread, it does not generally provide a complete barrier and smoke infiltration is likely. Sufficient smoke accumulation remote from the original fire location can present risk of a smoke explosion (see NIOSH Report 98-03 regarding a smoke explosion in Durango, Colorado restaurant). Alternately, fire extension into the truss loft above an exposure unit can result in ventilation controlled fire conditions, resulting in increased HRR if the void is opened (from above or below).

Extreme Fire Behavior: Smoke, air track, and flame indicators on Side C indicate that the fire in the truss loft may not have continued to develop past the initial ignition of accumulated smoke (fuel). It is possible that smoke accumulated in the truss loft above Exposure B and was ignited by subsequent extension from the fire unit. Depending on the fuel (smoke)/air mixture when flames extended into the space above Exposure B ignition could have resulted in a smoke explosion or a less violent fire gas ignition such as a flash fire.

Sandwich, MA

In the Sandwich incident, the extreme fire behavior occurred shortly after the hose team applied water to the soffit. However, this may or may not have been the precipitating event. As illustrated in Figure 3, the fire transitioned to a fully developed fire (likely due to the delay in suppression as the injured members were cared for). Blast effects on the structure are obvious.

Figure 3: Sandwich, MA: Conditions on Sides C and D

Note: Photos by Britt Crosby (http://www.capecodfd.com)

Potential Influencing Factors: The roof support system in this home appears to have been constructed of larger dimensional lumber (rather than lightweight truss construction). In addition, it is likely that the attic void spaces involved in this incident were large and complex (given the size of the dwelling and complex roof line). It appears that at least part of the home had a cathedral ceiling. Fire burning in the wood framing around the metal chimney would have allowed smoke (fuel) and hot gases to collect in the attic void in advance of fire extension.

Extreme Fire Behavior: The violence of the explosion (see blast damage to the roof on Side D in Figure 3) points to the potential for ignition of pre-mixed fuel (smoke) and air, resulting in a smoke explosion. However, it is also possible that failure of an interior ceiling (due to water or steam production from water applied through the soffit) could have increased ventilation to a ventilation controlled fire burning in the attic, resulting in a backdraft).

Fire Behavior Indicators

The information provided in news reports points to limited indication of potential for extreme fire behavior. One important question for each of us is how we can recognize this potential, even when indicators are subtle or even absent.

Important! A growth stage fire can present significant smoke and air track indicators, with increasing thickness (optical density), darkening color, and increasing velocity of smoke discharge. However, as discussed in The Hazard of Ventilation Controlled Fires, when the fire becomes ventilation controlled, indicators can diminish to the point where the fire appears to be in the incipient stage. This change in smoke and air track indicators was consistently observed during the full-scale fire tests of the influence of ventilation on fires in single-family homes conducted by UL earlier this year.

Even with an opening into another compartment or to the exterior of the building, a compartment fire can become ventilation controlled. Consider building factors including potential for fire and smoke extension into void spaces in assessing fire conditions and potential for extreme fire behavior. A ventilation controlled fire or flammable mixture of smoke and air may be present in a void space with limited indication from the exterior or even when working inside the structure.

Building Construction

Each of these incidents occurred in a wood frame structure. However, the construction in each case was somewhat different.

In Minneapolis, the house was likely balloon frame construction with full dimension lumber. As with many other structures with a “half-story”, the space under the pitched roof is framed out with knee walls to provide finished space. This design is not unique to legacy construction and may also be found with room-in-attic trusses. The void space behind the knee wall provides a significant avenue for fire spread. When involved in fire, opening this void space can quickly change fire conditions on the top floor as air reaches the (likely ventilation controlled) fire.

The incident in Harrisonburg involved a fire in a townhouse with the extreme fire behavior phenomena occurring in an exposure. While not reported, it is extremely likely that the roof support system was comprised of lightweight wood trusses. In addition, there was a reverse gable (possibly on Sides A and C) that provided an additional void. As previously indicated, the truss loft between dwelling units is typically separated by a one-hour rated draft stop. Unlike a fire wall, draft stops do not penetrate the roof and may be compromised by penetrations (after final, pre-occupancy inspection). Installed to code, draft stops slow fire spread, but may not fully stop the spread of smoke (fuel) into the truss lofts above exposures.

Firefighters in Sandwich were faced with a fire in an extremely large, wood frame dwelling. While the roof appeared to be supported by large dimensional lumber, it is likely that there were large void spaces as a result of the complex roofline. In addition, the framed out space around the metal chimney provided an avenue for fire and smoke spread from the lower level of the home to the attic void space.

Hazards and Tactics

Forewarned is forearmed! Awareness of the potential for rapid fire development when opening void spaces is critical. Given this threat, do not open the void unless you have a hoseline in hand (not just nearby).

Indirect attack can be an effective tactic for fires in void spaces. This can be accomplished by making a limited opening and applying water from a combination nozzle or using a piercing nozzle (which further limits introduction of air into the void).

If there are hot gases overhead, cool them before pulling the ceiling or opening walls when fire may be in void spaces. Pulses of water fog not only cool the hot gases, but also act as thermal ballast; reducing the potential for ignition should flames extend from the void when it is opened.

Lastly, react immediately and appropriately when faced with worsening fire conditions. Review my previous posts on Battle Drill (Part 1, Part 2, and Part 3). An immediate tactical withdrawal under the protection of a hoseline is generally safer than emergency window egress (particularly when ladders have not yet been placed to the window).

Ed Hartin, MS, EFO, MIFireE, CFO

Finally! It has been quite some time since my last post, but the CFBT-US web site and blog have been attacked twice by hackers WordPress and ISP upgrade issues have been a major challenge and it has taken some time to get things back to normal.

A Big Improvement, But More Work is Needed

The Fire Service in the United States saw a considerable reduction in firefighter line-of-duty deaths in 2009. However, our efforts to improve firefighter safety must persist. Recent events reinforce the need to ensure understanding of practical fire dynamics and have the ability to apply this understanding on the fireground.

Three recent incidents involving extreme fire behavior present an opportunity to examine and reflect on the hazards presented by fires and accumulation of excess pyrolizate and unburned products of combustion in attics and other void spaces.

Minneapolis, MN Residential Fire

At 1130 hours on Saturday, July 3, 2010 Minneapolis firefighters responded to a residential fire at 1082 17th Avenue SE. First arriving companies observed light smoke and flames showing from a two and one-half story wood-frame home. A crew opening up the kneewall on the A/D corner of Floor 3 was trapped on the third floor by rapid fire progress.

Note: Photo by Steve Skar

A department spokesperson indicated that as they opened up the walls “it flashed over on them”. News reports indicated that the blast threw Firefighter Jacob LaFerriere, across the room and that he was able to locate a window, where he exited and dropped to the porch roof, one floor below. Capt. Dennis Mack was able to retreat into the stairwell where he was assisted to the exterior by other crews operating on the fireground (Mathews, 2010; Radomski & Theisen, 2010).

News reports also reported that a witness stated that the “flashover was quite loud and within seconds heavy fire was venting from the attic area” (Mathews, 2010). A later statements by department spokespersons indicated introduction of oxygen when the wall was opened resulted in the flashover (Porter, 2010) and that a burst of flames blew out the south side of the roof (Radomski & Theisen, 2010).

Firefighter Jacob LaFerriere suffered third degree burns on his arms and upper body. Capt. Dennis Mack suffered second degree burns (Radomski & Theisen, 2010) and are as of Sunday, July 4 were in satisfactory condition in the Hennepin County Medical Center Burn Unit.

Harrisonburg, VA Townhouse Fire

On June 24, 2010 Harrisonburg, Virginia firefighters responded to an apartment fire off Chestnut Ridge Drive. First arriving companies encountered a fire in a townhouse style, wood frame apartment. Investigating possible extension into Exposure Bravo, Firefighters Chad Smith and Bradly Clark observed smoke and then flames in the attic. They called for a hoseline, but when the pulled the ceiling, conditions worsened as the room ignited. Both firefighters escaped through a second floor window (head first, onto ladders placed by exterior crews). Four other firefighters were inside Exposure B when the extreme fire behavior occurred. Two received second degree burns, one was treated for heat exhaustion, and the fourth was uninjured (Firehouse.com News, 2010; WHSV, 2020). Department spokespersons indicated that a backdraft occurred when fire gases built up in the attic.

Note: Photo by Allen Litten

Sandwich MA Residential Fire

At around noon on Memorial Day, Sandwich, Massachusetts firefighters responded to a residential fire at 15 Open Trail Road. On arrival they found a 5,000 ft² (464 m²) wood frame single-family dwelling with a fire on Side C (exterior) with extension into the home. Firefighters Daniel Keane and Lee Burrill stretched a handline through the door on Side A, knocking down the fire and extending the line out onto a deck on Side C. Fire was extending through a void containing a metal chimney flue on the exterior of the building. The crew on the hoseline was making good progress until they hit the soffit with a straight stream and an explosion occurred. The force of the blast knocked the crew over the deck railing and caused significant structural damage. Firefighter Keane suffered fractures of his neck and back while Firefighter Burrill experienced a severely fractured ankle (Fraser, 2010; D LeBlanc personal communication June 2010).

Note: Photos by Britt Crosby (http://www.capecodfd.com/)

Questions

One of these fires occurred in an older home of legacy construction, the other two occurred in relatively new buildings. One was a large contemporary home, likely with an open floor plan and large attic/trussloft voids. The other two occurred in buildings with smaller void spaces in the attic/trussloft.

1. What is similar about these incidents and what is different?
2. Based on the limited information currently available, what phenomena do you think occurred in each of the cases? What leads you to this conclusion?
3. What indicators might have pointed to the potential for extreme fire behavior in each of these incidents?
4. How might building construction have influenced fire dynamics and potential for extreme fire behavior in these incidents?
5. What hazards are presented by fires in attics/trusslofts and what tactics may be safe and effective to mitigate those hazards?

Late Breaking Information

Two firefighters and an officer from the Wharton Fire Department were trapped by rapid fire progress in a commercial fire at the Maxim Production Company in Boling, TX on July 3, 2010. The crew had advanced a hoseline into the 35,000 ft² (3252 m²) egg processing plant to cut off fire extension when they encountered rapidly worsening fire conditions. The two firefighters were able to escape, but Captain Thomas Araguz III was trapped and killed (Statter, D., 2010). More information will be provided on this incident as it becomes available.

References

Mathews, P. (2010). Two Minn. ffs burned in flashover. Retrieved July 4, 2010 from http://www.firehouse.com/news/top-headlines/two-minneapolis-firefighters-burned-flashover

Radomski, L & Theisen, S. (2010). Firefighters hospitalized after flashover identified. Retrieved July 4, 2010 from http://kstp.com/news/stories/S1637495.shtml?cat=1

Porter, K. (2010). 2 firefighters burned in Mpls. fire ID’d. Retrieved July 5, 2010 from http://www.kare11.com/news/news_article.aspx?storyid=856556&catid=396

WHSV. (2010) Harrisonburg firefighters talk about their close call. Retrieved July 5, 2010 from http://www.whsv.com/home/headlines/97127924.html

Firehouse.com News. (2010). Harrisonburg, Va. firefighters forced to bail out. Retrieved July 5, 2010 from http://www.firehouse.com/showcase/photostory/harrisburg-va-firefighters-have-bail-out

Fraser, D. (2010). Mass. firefighters thrown more than 30 Ft. by blast. Retrieved July 5, 2010 from http://www.firehouse.com/news/top-headlines/blast-throws-mass-firefighters-more-30-feet

Statter, D. (2010). Update: Captain Thomas Araguz III killed during 4-alarm fire at egg plant in Boling, Texas. http://statter911.com/2010/07/04/firefighter-killed-during-4-alarm-fire-at-egg-plant-details-from-wharton-county-texas/