Archive for the ‘Case Studies’ Category

NIOSH Report 2012-28
Thought & Observations

Wednesday, November 27th, 2013

After reading National Institute for Occupational Safety and Health (NIOSH) Death in the line of duty…2012-28, I was left scratching my head. For many years I have been a supporter of the Firefighter Fatality Investigation and Prevention Program and have served as an expert reviewer for several reports involving fatalities resulting from extreme fire behavior. As a friendly critic I have encouraged the NIOSH staff to improve their investigation and analysis of fire behavior related fatalities. Over the last several years there has been considerable improvement However, this latest report leaves a great deal to be desired. That said, there are a number of important lessons that can be drawn from this incident.

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Discussion of Fire Behavior

The Fire Behavior section of the report identified the attic as the origin of the fire and that the fire burning in the attic was ventilation limited. The report also identified that the enclosed rear porch was substantially involved. However, the report failed to discuss how the fire may have extended from the attic to the lower area of the porch (other than a statement that the BC notices “fire raining down in the enclosed porch area”.

The report correctly described the influence of the addition of air to a ventilation limited fire; increased heat release rate and potential to transition through flashover to a fully developed stage. However, the report failed to clearly articulate that there are two sides to the ventilation equation, air in and hot smoke and fire gases out. Flow path is critical to fire development and extension, and in this incident was likely one of the most significant factors in creating untenable conditions in the 2nd floor hallway.

It would have been useful to examine how the changes in ventilation resulting from opening of doors at the first floor level, existing openings in the attic (windows at the front and rear), opening of the door at the 2nd floor to extend the hoseline, and failure of the rear door may have influenced the flow path. While, the National Institute of Standards and Technology (NIST) modeling of this incident will shed considerable light on this subject, the physical evidence present at the fire scene could have informed discussion of flow path in the report.

Recommendation #1 states “Fire departments should ensure that fireground operations are coordinated with consideration given to the effects of horizontal ventilation on ventilation-limited fires”. This is a reasonable recommendation, but fails to speak to the importance of understanding flow path and the thermal effects of operating in the flow path downstream from the fire. In addition, while speaking to the importance of coordination, the report neglects to define exactly what that means; water on the fire concurrent with or prior to performing tactical ventilation.

Failure of the rear door established a flow path through the narrow, question mark shaped hallway and kitchen to the front stairway. Given the narrow width of this hall and its complex configuration, it is likely that there would be considerable mixing of hot smoke (fuel) and air providing conditions necessary for combustion. The dimensions of the space may also have influenced the velocity of the hot gases, increasing convective heat transfer.

The report did not speak to conditions initially observed in the kitchen and hallway or observed changes in conditions by members of other companies or the Engine 123 firefighter, prior to Captain Johnson’s collapse.

http://buyviagrageneric.com pharmacy Things to Think About: Conditions on floor 2 were quite tenable prior to failure of the 2nd floor rear door, but changed extremely quickly in the hallway when the door failed. It is important to consider potential changes in flow path resulting from tactical operations and fire effects. It is unclear if the crews working on the 2nd floor were aware of the extent or level of the fire in the rear porches (having observed conditions indicating an attic fire on approach). The BC addressed the fire in the rear, but the it is uncertain if the line stretched to the back of the building was in operation before door failed or if application through the attic window would have significantly impacted the fire in the lower areas of the porch.

Structure

The section of the report addressing the Structure provided a reasonably good overview of the construction of this building and identified that the 2nd floor ceiling had multiple layers. However, there was no discussion of what influence these multiple layers may have had (e.g., reducing the thermal signature of the fire burning above). One significant element missing from discussion of the structure was the open access between the rear porch and the attic that allowed ready extension of fire to the rear porches.

The report also failed to discuss the type of door between the 2nd floor living area and the rear porch, other than to mention in passing that it was metal. Closed doors frequently provide a reasonable barrier to fire spread, but in this case, the door failed following an undetermined period of fire exposure. This was likely a significant factor in changing the flow path and creation of untenable conditions on the 2nd floor.

Things to Think About: Closed doors can provide a significant fire barrier in the short term. However, it would be useful to examine door performance in greater depth to understand what happened in this incident.

Training and Experience

The section of the report addressing training and experience is exhaustive, providing an overview of state training requirements implemented in 2010 (well after the Captain would have attended recruit training). It was unclear if these requirements were implemented on a retroactive basis. The number of hours of training for various personnel involved in the incident were provided, but with little specificity as to content of that training.

These observations are not intended to infer that the training of the members involved was or may have been inadequate, but simply that if NIOSH is investigating a fire behavior related incident, it would be useful to speak to training focused on fire behavior, rather than a generic discussion of training.

It was also interesting to note that while the report spoke well of the Chicago Fire Department training program, it failed to mention that the CFD has been heavily involved in fire dynamics research with both NIST and Underwriters Laboratories (UL) for many years.

Things to Think About: If you are reading this, you likely are plugged into current research in fire dynamics and tactical operations. Share the knowledge and build a strong connection between theory and practical application on the fireground.

Other Observations

While the floor plan of the 2nd floor is useful in understanding the layout of that space, it does not provide a good basis to visualize the flow paths and changes in flow paths that influenced the tragic outcome of this incident. Providing a simple three dimensional drawing with ventilation openings would have significantly increased the clarity of the information provided.

Things to Think About: Don’t be a passive user of NIOSH reports. For a host of reasons, NIOSH does not include the names of Firefighters who have died in the line of duty, the agency they worked for, or the location of the incident (other than the state). However, this information is readily available and can provide additional information to help you understand the incident. In this case accessing the address of this incident (2315 W 50th Place, Chicago) allows the use of Google Maps satellite photos and street view to gain a better perspective of the exterior layout of the building and configuration of openings.

Final Thoughts

The NIOSH Firefighter Fatality Investigation and Prevention Program is an important and valuable resource to the fire service. Developing an understanding of causal factors related to firefighter fatalities is an important element in extending our knowledge and reducing the potential for future line of duty deaths. Firefighters often observe that NIOSH reports simply say the same thing over and over again. To some extent this is true, likely because Firefighters continue to die from the same things over and over again.

The fire service across the United States is making progress towards developing improved understanding of fire dynamics and the influence of tactical operations on fire behavior. This is in no small part due to the efforts of the UL Firefighter Safety Research Institute, NIST, and agencies such as the Chicago Fire Department and Fire Department of the City of New York (FDNY). However, we need to look closely at near miss incidents, those involving injury, and fatalities resulting from rapid fire progression and seek to develop a deeper understanding of the contributing and causal factors. The NIOSH Firefighter Fatality Investigation and Prevention Program can be a tremendous asset in this process, but more work needs to be done.

What’s Next

I just spent the last two days at UL’s Large Fire Lab for the latest round of Attic Fire Tests and will be headed to Lima, Peru the first week of December. While on the road I will be working on my thoughts and observations related to attic fire tactics. The simple answer is that there is no single answer, but these recent tests presented a few surprises and have given me a great deal to think about.

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Ed Hartin, MS, EFO, MIFireE, CFO

Control the Door and Control the Fire

Thursday, July 25th, 2013

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.

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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

What’s on Side C

Sunday, May 19th, 2013

The importance of the initial Incident Commander conducting 360o reconnaissance (or quickly obtaining information about conditions on sides of the building that are not visible) has been repeatedly emphasized in National Institute for Occupational Safety and Health (NIOSH) Death in the Line of Duty reports. This is important to assess both building and fire conditions. However, the building was there prior to the alarm of fire. Situational awareness (SA) does not only apply on the fireground, it must begin well before response. In structural firefighting, the built environment (including the building, its contents, and surroundings) are the ground we fight on and in. Situational assessment and size-up must be ongoing.

View from the Street

The Knead & Feed (see photo below), is an excellent restaurant in Coupeville, WA that serves breakfast and lunch. At first glance this building appears to be an older, one-story, wood frame, commercial with the Delta Exposure being a two-story building of similar construction. Given the age of the buildings, it would be reasonable to assume that they are of balloon frame construction. Looking beyond the building you can see Penn Cove, which provides an excellent view from the back of the restaurant.

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Reconnaissance on Side C

However, the view in this photo begs the question, what’s on Side C? Access to Side C is via an exterior stairway on Side Bravo. Descending this stairway provides access to another kitchen and dining area in the Basement which is not accessible from the interior of the restaurant on Floor 1. Continuing down the stairway, provides access to a bakery at the Basement 2 level. The stairway then continues down to the beach, providing access to Side C…provided that it is low tide.

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Obviously you get a considerably different picture from Side C! However, this is only the beginning of the story.

The Rest of the Story

It may appear that the small, one-story section of building between the Kneed and Feed restaurant and Exposure Delta is part of the exposure due to the color of the building on Side Alpha and the roof line on Side Charlie. However, this assumption would be incorrect as this is the main kitchen for the Kneed and Feed Restaurant.

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There is no interior access between Floor 1 and the Basement (in either the Kneed and Feed or Exposure Delta). The Basement and Basement 2 levels of the Kneed and Feed are accessed from the exterior on Side Bravo. The Basement of Exposure Delta (apartment unit) is accessed from the exterior on Side Delta. The second floor of Exposure Delta is accessed from the interior.

Continuing down to the Basement level, the section of the building below the main kitchen contains an unprotected stairwell that is open to the underside of the Basement of Exposure Delta and the void space under the wood sidewalk that runs in front of the restaurant and Exposure Delta. The Basement and Basement 2 levels are interconnected this stairway (non-fire rated doors provide access between the stairway and the Basement and Basement 2. This stairway is framed in at the Basement level, but simply enclosed by wood slats at the Basement 2 level.

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Strategic and Tactical Implications

This building presents considerable challenges due to its construction, configuration, attached exposure on Side Delta, and limited access. The following questions provide a starting point for discussion of strategic and tactical implications for this building and its most significant exposure:

  1. How might the construction and configuration of this building and exposure impact on the B-SAHF (building, smoke, air track, heat, and flame) indicators presented during a fire? How might this vary based on location (Floor 1, Basement, Basement 2)?
  2. How might the open stairwell between the Kneed and Feed and Exposure Delta impact on fire development and spread if the fire originated at one of the basement levels, or within the stairwell itself? How might communication between the stairwell and the wooden sidewalk on Side A impact firefighting operations (note that the sidewalk and void space below extends beyond the access points for Sides Bravo and Delta).
  3. How would the open framing under the Basement of Exposure Delta impact on potential for fire spread from the Kneed and Feed to Exposure Delta (particularly if a fire originated on the Basement or Basement 2 level)
  4. How would tidal conditions impact on access to Side Charlie for firefighting operations or placement of ladders for rescue or secondary egress from the Kneed and Feed or Exposure Delta (particularly the apartment unit in the Basement of Exposure Delta).
  5. What strategies and tactics would provide the safest and most effective approach to confining and extinguishing a fire in each level of this building?
  6. Given the significant threat to Exposure Delta should a fire occur in the Kneed and Feed, what strategies and tactics would be most effective in evacuating the occupants of this building and preventing extension?
  7. Given the multiple occupancies (restaurant, retail, and residential), how would time of day impact on firefighting operations in this building and exposure?

While this building is in my response area, you have challenging buildings in yours as well. Time to find out what’s in your patch! When on a medical response, automatic alarm, performing fire inspections, or just eating breakfast, take the time to look around and ask yourself what if…. Building Factors are the first element in B-SAHF and they are present prior to the fire. Pre-incident planning either on a formal basis (best choice) or informally as an individual or company is essential to safe and effective incident operations.

Thanks!

I would like to extend a special thank you to the owners and staff of the Kneed and Feed for providing the opportunity to learn about their building. While challenging from a firefighting perspective, this is one of the best places to have breakfast or lunch (but particularly breakfast) in our District! If you are on Whidbey Island, stop in for a meal, but bring your appetite.

Smoke is Fuel: Recognizing the Hazard

Sunday, May 12th, 2013

There has been an increasing awareness that smoke is fuel and that hot smoke overhead results in thermal insult (due to radiant heat transfer) and potential for ignition. However, the hazard presented by smoke as gas phase fuel can extend a considerable distance from the current area of fire involvement.

Reading the Fire

Print a copy of the B-SAHF Worksheet. Use the worksheet to document observed fire behavior indicators as you watch the first six minutes of the following video of an apartment fire that occurred on May 10, 2013 at the corner of Park Creek Lane and Hill Park Court in Churchville, NY. In particular, focus on fire behavior indicators that may point to changes in conditions. Don’t focus too much on the flame indicators presenting from the area involved, but pay particular attention to Building, Smoke, and Air Track indicators.

The following satellite photo and view of the Alpha/Delta Corner prior to the fire are provided to help orient you to the incident location. You can also go to Google Maps Street View and do a walk around on Sides Alpha (Hill Park Court) and Delta (Park Creek Lane) to view all four sides of the building.

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The following time sequence from the video of this incident illustrates the conditions immediately prior to and during the explosion. The extremely rapid increase in heat release rate during the explosion was not sustained (a transient event) as evidenced by conditions illustrated at 06:25.

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Building Factors

This building is of Type V construction with a wood truss roof system. In a large apartment building such as this, the trussloft is typically subdivided with draft stops comprised of gypsum board applied to one (or both) sides of a truss to stop rapid spread of fire within the trussloft. Draft stops should be thought of as speed bumps rather than a barrier (such as a firewall that extends through the roofline). While draft stops slow fire and smoke spread, they do not stop it completely and it is common for smoke to spread beyond the fire area despite the presence of draft stops.

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The small dimension framing materials used in truss construction have a high surface to mass ratio, increasing the speed with which they can be heated and increasing pyrolysis products in the smoke when heated under ventilation limited conditions.

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Note: The possible location of the draft stops is speculative as specific information regarding the construction of this building was not available at the time of this post. However, draft stops may be provided between the trussloft between units or based on the size of the trussloft without regard to the location of walls between units. Preplan inspections provide an opportunity to examine building factors that may be critical during an incident!

Smoke and Air Track Indicators

An important air track indicator in this incident was the strong wind blowing from the Alpha/Bravo Corner towards the Charlie/Delta Corner. The wind may have had some influence on ventilation in the trussloft above Exposures Bravo and Bravo 2, and definitively influenced other Smoke and Air Track indicators.

From the start of the video light colored smoke is visible at the peak of the roof above Exposure Bravo and Bravo 2, indicating that smoke had infiltrated areas of the trussloft that had not yet become involved in fire. Smoke that is light in color may be comprised of pyrolysis products and air and may be to lean or too rich to burn or it may be explosive See the video Smoke on the Firegear website for a good discussion of the characteristics of smoke (note that this video is currently undergoing validation).

The volume and color (smoke indicators), velocity and direction (air track indicators) above exposure Bravo 2 vary considerably from the start of the video until shortly before the explosion that occurred at 06:12 in the video. At 02:52 a firefighter entered Exposure Bravo 2 and a short time later at 03:47 a hoseline (dry) was stretched into this exposure and charged. It is unknown from watching the video if the firefighters on this line advanced to Floor 2 or if they took any action to change the ventilation profile (other than opening the door on Floor 1, Side Alpha). The exited after the explosion, but without haste, so it is likely that they were not on Floor 2 at the time of the explosion.

Smoke Explosion

Smoke explosion is described in a number of fire dynamics texts including Enclosure Fire Dynamics (Karlsson and Quintiere) and An Introduction to Fire Dynamics (Drysdale). However, Enclosure Fires by Swedish Fire Protection Engineer Lars-Göran Bengtsson (2001) provides the most detailed explanation of this phenomenon. Paraphrasing this explanation:

A smoke or fire gas explosion occurs when unburned pyrolysis products and flammable products of combustion accumulate and mix with air, forming a flammable mixture and introduction of a source of ignition results in a violent explosion of the pre-mixed fuel gases and air. This phenomenon generally occurs remote from the fire (as in an attached exposure) or after fire control.

In some cases, the fire serves as a source of ignition as it extends into the void or compartment containing the flammable mixture of smoke (fuel) and air.

Conditions Required for a Smoke Explosion

The risk of a smoke explosion is greatest in compartments or void spaces adjacent to, but not yet involved in fire. Infiltration of smoke through void spaces or other conduits can result in a well-mixed volume of smoke (fuel) and air. Smoke explosion creates a significant overpressure as the fuel and air are premixed and ignition results in a very large energy release. Several factors influence the violence of this type of explosion:

  • The degree of confinement (more confinement results in increased overpressure)
  • Mass of premixed fuel and air within the flammable range (more premixed fuel results in a larger energy release)
  • How close the mixture is to a stoichiometric concentration (the closer to an ideal mixture the faster the deflagration)

Potential Smoke Explosion Indicators

It is very difficult to predict a smoke explosion. However, the following indicators point to the potential for this phenomenon to occur:

  • Ventilation controlled fire (inefficient combustion producing substantial amounts of unburned pyrolysis products and flammable products of incomplete combustion)
  • Relatively cool (generally less than 600o C or 1112o F) smoke
  • Presence of void spaces, particularly if they are interconnected
  • Combustible structural elements
  • Infiltration of significant amounts of smoke into uninvolved compartments in the fire building or into exposures

Preventing a Smoke Explosion

As it is difficult to predict a smoke explosion, there are challenges to preventing their occurrence as well. However, general strategies would include 1) preventing smoke from accumulating in uninvolved spaces or 2) removing smoke that has accumulated remote from the fire (e.g., in attached exposures), or 3) a combination of the first two approaches.

Tactics to implement these strategies may include:

  • Pressurizing uninvolved spaces with a blower to prevent infiltration of smoke. This involves use of a blower for anti-ventilation by applying pressure without creating an exhaust, similar to what is done to pressurize a highrise stairwell. It is essential to check for extension prior to implementing this tactic!.
  • Horizontal ventilation of attached exposures to remove smoke, checking for extension, and then pressurization with a blower to prevent continued infiltration of smoke. If fire extension is found, pressurization without an exhaust opening must not be implemented!

Additional Resources

The following previous posts on the CFBT-US Blog may also be of interest in exploring the smoke explosion phenomena.

References

Bengtsson, L. (2001). Enclosure Fires. Retrieved May 12, 2013 from https://www.msb.se/RibData/Filer/pdf/20782.pdf .

 

Explosion at Harrington NJ Commercial Fire

Monday, March 11th, 2013

Updated with Additional Video

On March 10, 2013 five Harrison, New Jersey firefighters were injured in an explosion while working at a commercial fire at 600-602 Frank E. Rodgers Boulevard. The fire originated in a two-story commercial building at the corner of Frank E. Rodgers Boulevard North and Davis Street and extended into Exposures Charlie and Delta, two-story residential buildings.

Figure 1. Alpha/Bravo Corner and Exposure Charlie

600-602 Frank E. Rodgers Boulevard

Image from Google Maps, click on the link to walk around using Street View.

Reading the Fire

Before watching the video (or watching it again if you have already seen it), download and print the B-SAHF Worksheet. Using the pre-fire photo (figure 1) and observations during the video, identify key B-SHAF indicators that may have pointed to potential for extreme fire behavior in this incident.

Important! Keep in mind that there is a significant difference between focusing on the B-SAHF indicators in this context and observing them on the fireground. Here you know that an explosion will occur, so we have primed the pump so you can focus (and are not distracted by other activity).

Backdraft or Smoke Explosion

While smoke explosion and backdraft are often confused, there are fairly straightforward differences between these two extreme fire behavior phenomena. A smoke explosion involves ignition of pre-mixed fuel (smoke) and air that is within its flammable range and does not require mixing with air (increased ventilation) for ignition and deflagration. A backdraft on the other hand, requires a higher concentration of fuel that requires mixing with air (increased ventilation) in order for it to ignite and deflagration to occur. While the explanation is simple, it may be considerably more difficult to differentiate these two phenomena on the fireground as both involve explosive combustion.

  1. Did you observe any indicators of potential backdraft prior to the explosion?
  2. Do you think that this was a backdraft?
  3. What leads you to the conclusion that this was or was not a backdraft?
  4. If you do not think this was a backdraft, what might have been the cause of the explosion?

For more information in Backdraft, Smoke Explosion, and other explosive phenomena on the fireground, see:

Back at it!

I would like to say thanks to all of you who have sent e-mail or contacted me on Facebook inquiring about the status of the CFBT-US blog. The last several years have been extremely busy at Central Whidbey Island Fire & Rescue and my focus has been almost exclusively on the fire district. However, I am renewing my commitment to developing knowledge of practical fire dynamics throughout the fire service and will endeavor to return to posting on a regular basis. In addition, I am working on a series of short (10-minute) drills on fire dynamics that will be cross posted on the CFBT Blog and the Fire Training Toolbox.

Ed Hartin, MS, EFO, MIFIreE, CFO

Lima, Peru: Backdraft

Friday, December 24th, 2010

I recently traveled to Peru to deliver a presentation on 3D Firefighting at the First International Congress on Emergency First Response which was conducted by the Cuerpo General de Bomberos Voluntarios del Perú. This congress was being conducted in conjunction with the Peruvian fire service’s 150th anniversary celebration (establishment of Unión Chalaca No. 1, the first fire company).

In addition to my conference presentation, I spent 10 days teaching fire behavior and working alongside the Bomberos of Lima No.4, San Isidro No. 100, and Salvadora Lima No. 10.

Fire & Rescue Services in Lima, Peru

Lima is a city of 8 million people served by a volunteer fire service which provides fire protection, emergency medical services, hazmat response, and urban search and rescue. The stations that I worked in were busy with call volumes from 2000 to 5000 responses in an urban environment ranging from modern high-rise buildings to poor inner city neighborhoods. Each station was equipped with an engine, truck, rescue, and ambulance. Staffing varied throughout the day with some units being cross staffed or un-staffed due to limited staffing. At other times, units were fully staffed (5-6 on engines and trucks, 4 on rescues, and 3 on ambulances). While the Peruvian fire service has some new apparatus, many apparatus are old and suffer from frequent mechanical breakdown. Faced with high call volume and old apparatus and equipment, the Firefighters and Officers displayed a tremendous commitment to serve their community.

The firefighters I encountered had a tremendous thirst for knowledge and commitment to learning. My friend Giancarlo had arranged for a short presentation on fire behavior for a Tuesday evening and the room was packed. Class was scheduled from 20:00 until 22:00. However, when we reached 22:00, the firefighters wanted to stay and continue class. We adjourned at 24:00. This continued for the next two nights. Sunday, between calls, we had breakfast at San Isidro No. 100 and then conducted a hands-on training session on nozzle techniques and hose handling. At the start of class, Firefighter Adryam Zamora from Santiago Apostol No. 134, related that he used the 3D techniques we had discussed in class at an apartment fire the night before with great success.

Staff Ride

Staff rides began with the Prussian Army in the mid-1800s and are used extensively by the US Army and the US Marine Corps. A staff ride consists of systematic preliminary study of a selected campaign or battle, an extensive visit to the actual sites associated with that campaign, and an opportunity to integrate the lessons derived from these elements. The intent of a staff ride is to put participants in the shoes of the decision makers on a historical incident in order to learn for the future. Wildland firefighters have adapted the staff ride concept and have used it extensively to study large wildland fires, fatalities, and near miss incidents. However, structural firefighters have not as commonly used this approach to learning from the past.

When I traveled to Lima, I only knew two Peruvians; Teniente Brigadier CBP (a rank similar to Battalion Chief in the US fire service) Giancarlo Passalaqua and Teniente CBP (Lieutenant) Daniel Bacigalupo. However, I left Lima with a much larger family with many more brothers and sisters.

Backdraft!

Many firefighters have seen the following video of an extreme fire behavior event that occurred in Lima, Peru. This video clip often creates considerable discussion regarding the type of fire behavior event involved and exactly how this might have occurred. Photos and video of fire behavior are a useful tool in developing your understanding and developing skill in reading the fire. However, they generally provide a limited view of the structure, fire conditions, and incident operations.

Note: While not specified in the narrative, this video is comprised of segments from various points from fairly early in the incident (see Figure 3, to later in the incident immediately before, during, and after the backdraft).

When I was invited to Lima, I asked my friend Teniente Brigadier CBP Giancarlo Passalaqua who worked at this incident, if it would be possible to talk to other firefighters who were there and to walk the ground around the building to gain additional insight into this incident.

The Rest of the Story

The morning after I arrived, I was sitting in the kitchen of San Isidro No. 100 and was joined in a cup of coffee by Oscar Ruiz, a friendly and engaging man in civilian clothing who I assumed was a volunteer firefighter at the station. After my friend Giancarlo arrived, he told me that Oscar was actually Brigadier CBP (Deputy Chief) Oscar Ruiz from Lima No. 4 and one of the two firefighters who had been in the bucket of the Snorkel pictured in the video. Oscar and I had several opportunities to spend time together over the course of my visit and he shared several observations and insights into this incident.

At 11:00 hours on Saturday, March 15, 1997, two engines, a ladder, heavy rescue, medic unit, and command officer from the Lima Fire Department were dispatched to a reported commercial fire at the intersection of Luis Giribaldi Street and 28 de Julio Street in the Victoria section of Lima.

Companies arrived to find a well developed fire on Floor 2 of a 42 m x 59 m (138’ x 194’) three-story, fire resistive commercial building, The structure contained multiple, commercial occupancies on Side A (Luis Giribaldi Street) and Side B (28 De Julio Street). Floors 2 and 3 were used as a warehouse for fabric (not as a plastics factory as reported in the video clip). The building was irregularly shaped with attached exposures on Sides B and C.

Exposure A was a complex of single-story commercial occupancies, Exposure B was an attached two-story commercial complex, Exposure C was an attached three story commercial complex, and Exposure D was a three story apartment building. All of the exposures were of fire resistive construction.

Figure 1. Plot Plan

Floors 2 and 3 had an open floor plan and were used for storage of a large amount of fabric and other materials. As illustrated in Figure 1, there were two means of access to Floors 2 and 3; a stairway on Side A and an open shaft and stairway on Side C.

Due to heavy fire involvement, operations focused on a predominantly defensive strategy to control the fire in this multi-occupancy commercial building. The incident commander called for a second, and then third alarm. Defensive operations involved use of handlines and an aerial ladder working from Side A and in the Side A stairwell leading to Floor 2. However, application of water from the ladder pipe had limited effect (possibly because of the depth of the building and burning contents shielded from direct application from the elevated stream.

Figure 2. Early Defensive Operations

Note: Video screen shot from the intersection of Luis Giribaldi and 28 de Julio.

The third alarm at 14:05 hours brought two engines and articulating boom aerial platform (Snorkel) from Lima 4 to the incident. Snorkel 4, under the command of Captain Roberto Reyna was tasked to replace the aerial ladder which had been operating on Side A and operate an elevated master stream to control the fire on Floor 2 (Figure 2).

Placing their master stream into operation Teniente Oscar Ruiz and Captain Roberto Reyna worked to darken the fire on Floor 2. As exterior streams were having limited effect, Snorkel 4 was ordered to discontinue operation and began to lower the bucket to the ground. At the same time, efforts were underway to gain access to the building from Side C. Using forcible entry tools, firefighters breached the large loading dock door leading to the vertical shaft and stairwell in the C/D quadrant of the building.

Prior to opening the large loading dock door on Side C (Charlie/Delta Corner), a predominantly bi-directional air track is visible at ventilation openings on Side C. Flaming combustion from windows on Side A was likely limited to the area at openings with a bidirectional air track. Combustion at openings on Side A likely consumed the available atmospheric oxygen, maintaining extremely ventilation controlled conditions with a high concentration of gas phase fuel from pyrolyzing synthetic fabrics deeper in the building.

The ventilation profile when Snorkel 4 initially began operations included intake of air through the open interior stairwell (inward air track) serving floors 1-3 and from the lower area of windows which were also serving as exhaust openings (bi-directional air track). Interview of members operating at the incident indicates that there were few if any ventilation openings (inlet or exhaust) on Sides B, C, or D prior to creation of an access opening on Floor 1 Side C.

At approximately 15:50, Snorkel 4 was ordered to stop flowing water. As smoke conditions worsened, they did so and began to lower the aerial tower to the ground. At the same time, crews working to gain access to Floor 1 on Side C, breached the large loading dock door. A strong air track developed, with air rushing in the large opening and up the open vertical shaft leading to the upper floors as illustrated in Figure 3.

Figure 3. Layout of Floors 1 and 2

As the Snorkel was lowered to the ground, Teniente Oscar Ruiz observed a change in smoke conditions, observing a color change from gray/black to “phosphorescent yellow” (yellowish smoke can also be observed in the video clip of this incident). Less than two minutes after the change in ventilation profile, a violent backdraft occurred, producing a large fireball that engulfed Captain Roberto Reyna and Teniente Oscar Ruiz in Snorkel 4 (see Figure 4). The blast seriously injured the crew of Snorkel 4 along with numerous other members from stations Lima 4, Salvadora Lima 10, and Victoria 8 who were located in the Stairwell (these members were blown from the building) and on the exterior of Side A.

This incident eventually progressed to a fifth alarm with 63 companies from 26 of Lima’s 58 stations in attendance.

Figure 4. Backdraft Sequence

Watch the video again; keeping in mind the changes in air track that resulted from breaching the loading dock door on Side C. Consider the B-SAHF (Building, Smoke, Air Track, Heat, and Flame) indicators that are present as the video progresses.

Luis Giribaldi Street and 28 de Julio Street Today

The building involved in this incident is still standing and while it has been renovated, is much the same as it was in 1997. On December 6, 2010, Teniente Brigadier Giancarlo Passalaqua, myself and Capitáin Jordano Martinez went to Luis Giribaldi and 28 de Julio to walk the ground and gain some insight into this significant incident.

Figure 5. Luis Giribaldi Street

As illustrated in Figure 5, Luis Giribaldi Street is a one-way street with parking on both sides and overhead electrical utility lines.

Figure 6. A/D Corner

There are a number of obvious structural changes that have been made since the fire. Including installation of window glazing flush with the surface of the building (the original windows can be seen behind these outer windows).

Figure 7. Snorkel 4’s Position

Figure 7 shows the view from Snorkel 4’s position, just to the left of center is the entry way leading to the stairwell used to access Floors 2 and 3. Piled fabric and other materials can be seen through the windows of Floors 2 and 3, likely similar in nature to conditions at the time of the incident.

Figure 8. Side A

Figure 8 provides a view of Side A and Exposure B, which appears to be of newer construction and having a different roofline than the fire building. The appearance of the left and right sides of the fire building are different, but this is simply due to differences in masonry veneer on the exterior of the building.

Figure 9. A/B Corner

Figure 10. Side B

Figure 11. B/C Corner

As illustrated in Figures 10-11 this block is comprised of several attached, fire resistive buildings. It is difficult to determine the interior layout from the exterior as there are numerous openings in interior walls due to renovations and changes in occupancy over time. The floor plan illustrated in Figure 4 is the best estimate of conditions at the time of the fire based on interviews with members operating at the incident.

Figure 12. Side C and the Loading Dock Door

Figure 12shows Side C of the fire building and Exposure C and the loading dock door that was breached to provide access to the fire building from Side C immediately prior to the backdraft.

Figure 13. Side D and Exposure D

Figure 13illustrates the proximity of Exposure D, a three-story, fire-resistive apartment building.

Lessons Learned

This incident presented a number of challenges including a substantial fuel load (in terms of both mass and heat of combustion), fuel geometry (e.g., piled stock), and configuration (e.g., shielded fire, difficult access form Side C). Analysis of data from the short video clip and discussion of this incident with those involved provides a number of important lessons.

  • Knowledge of the buildings in your response area is critical to safe and effective firefighting operations. While a challenging task, particularly in a large city such as Lima, developing familiarity with common building types and configurations and pre-planning target hazards can provide a significant fireground advantage.
  • Reading the fire is essential to both initial size-up and ongoing assessment of conditions. In this incident, fire behavior indicators may have provided important cues needed to avoid the injuries that resulted from this extreme fire behavior event.
  • Some fire behavior indicators can be observed from one position, while others may not. It is particularly important that individuals in supervisory positions be able to integrate observations from multiple perspectives when anticipating potential changes in fire behavior.
  • Any opening, whether created for tactical ventilation or for entry has the potential to change the ventilation profile. It is important to consider potential changes in fire behavior that may result from changes in ventilation (particularly when the fire is ventilation controlled).
  • Communication and coordination are critical during all fireground operations. It is essential to communicate observations of key fire behavior indicators and changes in conditions to Command. Tactical ventilation (or other tactical operations that may influence fire behavior) must be coordinated with fire attack.
  • Protective clothing and self-contained breathing apparatus are a critical last line of defense when faced with extreme fire behavior (even when engaged in exterior, defensive operations).

I would like to recognize the members of the Peruvian fire service who assisted in my efforts to gather information about this incident and identify the important lessons learned. In particular, I would like to thank Teniente Brigadier Giancarlo Passalaqua, Brigadier CBP Oscar Ruiz, and my brothers at Lima 4 who generously shared their home, their time, and their knowledge.

Ed Hartin, MS, EFO, MIFIreE, CFO

When I was invited to Lima, I asked my friend Teniente Brigadier CBP Giancarlo Passalaqua who worked at this incident, if it would be possible to talk to other firefighters who were there and to walk the ground around the building to gain additional insight into this incident.

Homewood, IL LODD: Part 2

Sunday, November 21st, 2010

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 360o 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?

Homewood, IL LODD

Saturday, November 13th, 2010

Introduction

While formal learning is an essential part of firefighters’ and fire officers’ professional development, informal learning is equally important, with lessons frequently shared through the use of stores. Stories are about sharing knowledge, not simply about entertainment. It is their ability to share culture, values, vision and ideas that make them so critical. They can be one of the most powerful learning tools available (Ives, 2004). “Only by wrestling with the conditions of the problem at hand and finding his own way out, does [the student] think” (Dewey, 1910, p. 188).

Developing mastery of the craft of firefighting requires experience. However, it is unlikely that we will develop the base of knowledge required simply by responding to incidents. Case studies provide an effective means to build our knowledge base using incidents experienced by others. This case is particularly significant as the circumstances could be encountered by almost any firefighter.

Aim

Firefighters and fire officers recognize and respond appropriately to the hazards of ventilation controlled fires in small, Type V (wood frame), single family dwellings.

References

National Institute for Occupationsl Safey and Health (NIOSH). (2010). Death in the line of duty: Report F2010-10. Retrieved October 22, 2010 from http://www.cdc.gov/niosh/fire/pdfs/face201010.pdf.

Ives, B. (2004) Storytelling and Knowledge Management: Part 2 – The Power of Stories. Retrieved May 6, 2010 from http://billives.typepad.com/portals_and_km/2004/08/storytelling_an_1.html

Dewey, J. (1910) Democracy and education. New York: McMillan

Learning Activity

Review the incident information and discuss the questions provided. Focus your efforts on understanding the interrelated impact of ventilation and fire control tactics on fire behavior. Even more important than understanding what happened in this incident is the ability to apply this knowledge in your own tactical decision-making.

The Case

This case study was developed using NIOSH Death in the Line of Duty: Report F2010-10 (NIOSH, 2010).

On the evening of March 30, 2010, while operating at a fire in a small single family dwelling, Firefighter/Paramedic Brian Carey and Firefighter/Paramedic Kara Kopas were assigned to assist in advancement of a 2-1/2” handline for offensive fire attack and to support primary search. Shortly after entering the building conditions deteriorated and they were trapped by rapid fire progression. Firefighter Kopas suffered 2nd and 3rd degree burns to her lower back, buttocks, and right wrist. Firefighter Carey died from carbon monoxide poisoning and inhalation of smoke and soot. A 84 year old male civilian occupant also perished in the fire.

Figure 1. Side A Post Fire

Side A Post Fire

Note: National Institute for Occupational Safety and Health (NIOSH)

Building Information

This incident involved a 950 ft2 (88.26 m2), one-story, single family dwelling constructed in 1951. The house was of Type V (wood frame) construction with a hip roof covered with asphalt shingles. The roofline of the hip roof provided a small attic space. Sometime after the home was originally constructed an addition C was built that attached the house to a garage located on Side C. Compartment linings were drywall. The house, garage, and addition were all constructed on a concrete slab.

There were several openings between the house and addition, including two doors, and two windows (see Figure 3).

Note: The number and nature of openings between the garage and addition is not reported, but likely included a door and possibly a window (given typical garage construction). NIOSH investigators did not determine if the doors and windows between the house, addition, and garage were open or closed at the time of the fire as they were consumed by the fire and NIOSH did not interview the surviving occupant (S. Wertman, personal communication, November 17, 2010). The existence and position of the door shown in the wall between the addition and garage is speculative (based on typical design features of this type of structure).

Figure 2. Plot Plan and Apparatus Positioning

Figure 3. Floor Plan 17622 Lincoln Avenue

The Fire

Investigators believe that the fire originated in an addition that was constructed between the original home and the two-car garage. The surviving occupant reported that she observed black smoke and flames from underneath the chair that her disabled husband was sitting in.

The addition was furnished as a family room and fuel packages included upholstered furniture and polyurethane padding. The civilian victim also had three medical oxygen bottles (one D Cylinder (425 L) and two M-Cylinders (34 L). It is not know if the oxygen in these cylinders was a factor in fire development. The garage contained a single motor vehicle in the garage and other combustible materials.

After calling 911 and attempting to extinguish the fire, the female occupant exited the building. NIOSH Death in the Line of Duty Report 2010-10 did not specify this occupants egress path or if she left the door through which she exited open or closed (NIOSH did not interview the occupant, she was interviewed by local fire and law enforcement authorities). The NIOSH investigator (personal communications S. Wertman, November 17, 2010) indicated that the occupant likely exited through the exterior door in the addition or through the door on Side A. Give rapid development through flashover in the addition, it is likely that the exterior door in the addition or door to the garage was open, pointing to the likelihood that the occupant exited through this door. Subsequent rapid extension to the garage was likely based on design features of the addition and garage or some type of opening between these two compartments. As similar extension did not occur in the house, it is likely that the door and windows in the Side C wall of the house were closed.

In the four minutes between when the incident was reported (20:55 hours) and arrival of a law enforcement unit (20:59), the fire in the addition had progressed from the incipient stage to fully developed fire conditions in both the addition and garage.

Dispatch Information

At 2055 hours on March 30, 2010, dispatch received a call from a resident at 17622 Lincoln Avenue stating that her paralyzed husband’s chair was on fire and that he was on oxygen. The first alarm assignment consisting of two engines, two trucks, a squad, and ambulance, and fire chief was dispatched at 2057.

Table 1. On-Duty and Additional Unit Staffing of First Alarm Resources

Unit

Staffing

Engine 534 Lieutenant, Firefighter, Engineer
Ambulance 564 2 Firefighter Paramedics
Truck 1220 (Auto Aid Department) Lieutenant, 2 Firefighters, Engineer
Engine 1340 (Auto Aid Department) Lieutenant 3 Firefighters, Engineer
Truck 1145 (Auto Aid Department) Lieutenant, 2 Firefighters, Engineer
Squad 440 (Auto Aid Department) Lieutenant, 3 Firefighters
Chief Chief

Note: This table was developed by integrating data from Death in the Line of Duty Report 2010-10 (NIOSH, 2010).

Weather Conditions

The weather was clear with a temperature of 12o C (53o F). Firefighters operating at the incident stated that wind was not a factor.

Conditions on Arrival

A law enforcement officer arrived prior to fire companies and reported that the house was “fully engulfed” and that the subject in the chair was still in the house.

Truck 1220 (T-1220) arrived at 2101, observed that the fire involved a single family dwelling, and received verbal reports from law enforcement and bystanders that the male occupant was still inside. Note: The disabled male occupant’s last known location was in the addition between the house and garage, but it is unknown if this information was clearly communicated to T-1220 or to Command (E-534 Lieutenant).

Engine 534 (E-534) arrived just behind T-1220 and reported heavy fire showing. E-534 had observed flames from Side C during their response and discussed use of a 2-1/2” (64 mm) handline for initial attack.

Firefighting Operations

Based on the report of a trapped occupant, T-1220B (Firefighter and Apparatus Operator) prepared to gain entry and conduct primary search. Note: Based on data in NIOSH Death in the Line of Duty Report 2010-10, it is not clear that this task was assigned by the initial Incident Commander (Engine 534 Lieutenant). It appears that this assignment may have been made by the T-1220 Lieutenant, or performed simply as a default truck company assignment for offensive operations at a residential fire.

Upon arrival, the E-534 Lieutenant assumed Command and transmitted a size-up report indicating heavy fire showing. The Incident Commander(E-534 Lieutenant) assisted the E-534 Firefighter with removal of the 1-3/4” (45 mm) skid load from the solid stream nozzle on the 2-1/2” (64 mm) hose load and stretching the 2-1/2” (64 mm) handline to the door on Side A. The E-534 Apparatus Operator charged the line with water from the apparatus tank and then hand stretched a 5” supply line to the hydrant at the corner of Lincoln Avenue and Hawthorne Road with the assistance of a Firefighter from T-1220.

Figure 4. Initiation of Primary Search

The Incident Commander (E-534 Lieutenant) assisted T-1220B in forcing the door on Side A. T-1220B made entry without a hoseline and began a left hand search as illustrated in Figure 4, noting that the upper layer was banked down to within approximately 3’ (0.9 m) from the floor).

Arriving immediately after E-534, the crew of A-564 donned their personal protective equipment and reported to the Incident Commander at the door on Side A, where he and the E-534 Firefighter were preparing to make entry with the 2-1/2” hoseline. The Incident Commander then assigned A-564 to work with the E-534 Firefighter to support search operations and control the fire.

T-1220 initiated roof operations and began to cut a ventilation opening on Side A near the center of the roof. Note: Based on data in NIOSH Death in the Line of Duty Report 2010-10, it is not clear that this task was assigned by the initial Incident Commander (Engine 534 Lieutenant). It appears that this assignment may have been made by the T-1220 Lieutenant, or performed simply as a default truck company assignment for offensive operations at a residential fire.

As illustrated in Figure 5, a large body of fire can be observed on Side C and a bi-directional air track is evident at the point of entry on Side A with dark gray smoke pushing from the upper level of the doorway at moderate velocity. All windows on Sides A and B were intact, with evidence of soot and/or condensed pyrolizate on the large picture window adjacent to the door on Side A.

Figure 5. Conditions Viewed from the Alpha/Bravo Corner at Approximately

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

The Firefighter from E-534 took the nozzle and assisted by Firefighters Carey and Kopas (A-564) stretched the 2-1/2” (64 mm) handline through the door on Side A and advanced approximately 12’ (3.66 m) into the kitchen. As they advanced the hoseline, they were passed by T-1220B, conducting primary search. The E-534 Firefighter, Firefighter Kopas (A-564), and T-1220B observed thick (optically dense), black smoke had dropped closer to the floor and that the temperature at floor level was increasing.

Figure 6. Primary Search and Fire Control Crews

Questions

Take a few minutes and consider the answers to the following questions. Remember that it is much easier to sort through the information presented by the incident when you are reading a blog post, than when confronted with a developing fire with persons reported!

  1. What B-SAHF (Building, Smoke, Air Track, Heat, & Flame) indicators were observed during the initial stages of this incident?
  2. What stage(s) of fire and burning regime(s) were present in the building when T-1220 and E-534 arrived? Consider potential differences in conditions in the addition, garage, kitchen, bedrooms, and living room?
  3. What would you anticipate as the likely progression of fire development over the next several minutes? Why?
  4. How might tactical operations (positively or negatively) influence fire development?

Ed Hartin, MS, EFO, MIFireE, CFO

Note: The number and nature of openings between the garage and addition is not reported, but likely included a door and possibly a window (given typical garage construction). NIOSH investigators did not determine if the doors and windows between the house, addition, and garage were open or closed at the time of the fire as they were consumed by the fire and NIOSH did not interview the surviving occupant (S. Wertman, personal communication, November 17, 2010). The existence and position of the door shown in the wall between the addition and garage is speculative (based on typical design features of this type of structure).

Townhouse Fire: Washington, DC
Computer Modeling-Part 2

Monday, October 5th, 2009

This post continues study of an incident in a townhouse style apartment building in Washington, DC with examination of the extreme fire behavior that took the lives of Firefighters Anthony Phillips and Louis Mathews. As discussed in Townhouse Fire: Washington, DC-Computer Modeling Part I, this was one of the first cases where the NIST Fire Dynamics Simulator (FDS) software was used in forensic fire scene reconstruction (Madrzykowski and Vettori, 2000).

Quick Review

As discussed in prior posts, crews working on Floor 1 to locate the fire and secure the door to the stairwell were trapped and burned as a result of rapid progression of a fire in the basement up the open interior stairway after an exterior sliding glass door was opened to provide access to the basement. For detailed examination of incident operations and fire behavior, see:

Figure 1. Conditions at Approximately 00:28

cherry_rd_sidebyside

Note: From Report from the Reconstruction Committee: Fire at 3146 Cherry Road NE, Washington DC, May 30, 1999, p. 29 & 32. District of Columbia Fire & EMS, 2000.

Smokeview

Smokeview is a visualization program used to provide a graphical display of a FDS model simulation in the form of an animation or snapshot. Snapshots illustrate conditions in a specific plane or slice within the building. Three vertical slices are important to understanding the fire dynamics involved in the Cherry Road incident: 1) midline of the door on Floor 1, Side A, 2) midline of the Basement Door, Side C, and midline of the Basement Stairwell (see Figure 2). Imagine that the building is cut open along the slice and that you can observe the temperature, oxygen concentration, or velocity of gas movement within that plane.

Figure 2. Perspective View of 3146 Cherry Road and Location of Slices

slices_sr

Note: From Simulation of the Dynamics of the Fire at 3146 Cherry Road NE Washington D.C., May 30, 1999, NISTR 6510 (p. 15) by Dan Madrzykowski and Robert Vettori, 2000, Gaithersburg, MD: National Institute for Standards and Technology.

In addition to having an influence on heat release rate, the location and configuration of exhaust and inlet openings determines air track (movement of smoke and air) and the path of fire spread. In this incident, the patio door providing access to the basement at the rear acted as an inlet, providing additional air to the fire. The front door and windows on the first floor opened for ventilation served as exhaust openings and provided a path for fire travel when the conditions in the basement rapidly transitioned to a fully developed fire.

Figures 3-10 illustrate conditions at 200 seconds into the simulation, which relates to approximately 00:27 during the incident, the time at which the fire in the basement transitioned to a fully developed stage and rapidly extended up the basement stairway to Floor 1. Data is presented as a snapshot within a specific slice. Temperature and velocity data are provide for each slice (S1, S2, & S3 as illustrated in Figure 2).

Figure 3. Temperature Along Centerline of Basement Door Side C (S1) at 200 s

basement_door_temp_slice_sr

Note: From Simulation of the Dynamics of the Fire at 3146 Cherry Road NE Washington D.C., May 30, 1999, NISTR 6510 (p. 17) by Dan Madrzykowski and Robert Vettori, 2000, Gaithersburg, MD: National Institute for Standards and Technology.

Figure 4. Vector Representation of Velocity Along Centerline of Basement Door Side C (S1) at 200 s

basement_door_velocity_slice_sr

Note: From Simulation of the Dynamics of the Fire at 3146 Cherry Road NE Washington D.C., May 30, 1999, NISTR 6510 (p. 18) by Dan Madrzykowski and Robert Vettori, 2000, Gaithersburg, MD: National Institute for Standards and Technology.

Figure 5. Oxygen Concentration Along Centerline of Basement Door Side C (S1) at 200 s

basement_door_o2_slice_sr

Note: From Simulation of the Dynamics of the Fire at 3146 Cherry Road NE Washington D.C., May 30, 1999, NISTR 6510 (p. 23) by Dan Madrzykowski and Robert Vettori, 2000, Gaithersburg, MD: National Institute for Standards and Technology.

Figure 6. Temperature Slice Along Centerline of Basement Stairwell (S2) at 200 s

stairwell_temp_slice_sr

Note: From Simulation of the Dynamics of the Fire at 3146 Cherry Road NE Washington D.C., May 30, 1999, NISTR 6510 (p. 21) by Dan Madrzykowski and Robert Vettori, 2000, Gaithersburg, MD: National Institute for Standards and Technology.

Figure 7. Vector Representation of Velocity Along Centerline of Basement Stairwell (S2) at 200 s

stairwell_velocity_slice_sr

Note: From Simulation of the Dynamics of the Fire at 3146 Cherry Road NE Washington D.C., May 30, 1999, NISTR 6510 (p. 22) by Dan Madrzykowski and Robert Vettori, 2000, Gaithersburg, MD: National Institute for Standards and Technology.

Figure 8. Oxygen Concentration Along Centerline of Basement Stairwell (S2) at 200 s

stairwell_o2_slice_sr

Note: From Simulation of the Dynamics of the Fire at 3146 Cherry Road NE Washington D.C., May 30, 1999, NISTR 6510 (p. 24) by Dan Madrzykowski and Robert Vettori, 2000, Gaithersburg, MD: National Institute for Standards and Technology.

Figure 9. Temperature Slice Along Centerline of Floor 1 Door Side A (S3) at 200 s

front_door_temp_slice_sr

Note: From Simulation of the Dynamics of the Fire at 3146 Cherry Road NE Washington D.C., May 30, 1999, NISTR 6510 (p. 19) by Dan Madrzykowski and Robert Vettori, 2000, Gaithersburg, MD: National Institute for Standards and Technology.

Figure 10. Vector Representation of Velocity Along Centerline of Floor 1 Door Side A (S3) at 200 s

front_door_velocity_slice_sr

Note: From Simulation of the Dynamics of the Fire at 3146 Cherry Road NE Washington D.C., May 30, 1999, NISTR 6510 (p. 20) by Dan Madrzykowski and Robert Vettori, 2000, Gaithersburg, MD: National Institute for Standards and Technology.

Figure 11. Perspective Cutaway, Flow/Temperature, Velocity, and O2 Concentration

cherry_road_cutaway_sr

Figure 12. Thermal Exposure Limits in the Firefighting Environment

thermal_environment

Note: Adapted from Measurements of the firefighting environment. Central Fire Brigades Advisory Council Research Report 61/1994 by J.A. Foster & G.V. Roberts, 1995. London: Department for Communities and Local Government and Thermal Environment for Electronic Equipment Used by First Responders by M.K. Donnelly, W.D. Davis, J.R. Lawson, & M.J. Selepak, 2006, Gaithersburg, MD: National Institute of Standards and Technology.

Compartment Fire Thermal Hazards

The temperature of the atmosphere (i.e., smoke and air) is a significant concern in the fire environment, and firefighters often wonder or speculate about how hot it was in a particular fire situation. However, gas temperature in the fire environment is a bit more complex than it might appear on the surface and is only part of the thermal hazard presented by compartment fire.

Tissue temperature and depth of penetration determine the severity of a thermal burn. Temperature and penetration are dependent on the amount of energy absorbed and the duration of the thermal insult as well as the properties of human tissue. In a compartment fire, firefighters absorb energy from any substance that has a temperature above 37o C (98.6o F), including hot compartment linings, contents, the hot gas layer, and flames. The dominant mechanisms of heat transfer involved in this process are convection and radiation (although conduction through personal protective equipment is also a factor to be considered).

The total thermal energy received is described in joules per unit area. However, the speed or rate of energy is transferred may be more important when assessing thermal hazard. Heat (thermal) flux is used to define the rate of heat transfer and is expressed in kW/m2 (Btu/hr/ft2).

One way to understand the interrelated influence of radiant and convective heat transfer is to consider the following scenario. Imagine that you are standing outside in the shade on a hot, sunny day when the temperature is 38o C (100o F). As the ambient temperature is higher than that of your body, energy will be transferred to you from the air. If you move out of the shade, your body will receive additional energy as a result of radiant heat transfer from the sun.

Convective heat transfer is influenced by gas temperature and velocity. When hot gases are not moving or the flow of gases across a surface (such as your body or personal protective equipment) is slow, energy is transferred from the gases to the surface (lowering the temperature of the gases, while raising surface temperature). These lower temperature gases act as an insulating layer, slowing heat transfer from higher temperature gases further away from the surface. When velocity increases, cooler gases (which have already transferred energy to the surface) move away and are replaced by higher temperature gases. When velocity increases sufficiently to result in turbulent flow, hot gases remain in contact with the surface on a relatively constant basis, increasing convective heat flux.

Radiant heat transfer is influenced by proximity and temperature of the radiating body. Radiation increases by a factor of four when distance to the hot material is reduced by half. In addition, radiation increases exponentially (as a function of the fourth power) as absolute temperature increases.

Thermal hazard may be classified based on hot gas temperature and radiant heat flux (Foster & Roberts, 1995; Donnelly, Davis, Lawson, & Selpak, 2006) with temperatures above 260o C (500o F) and/or radiant heat flux of 10 kW/m2 (3172 Btu/hr/ft2) being immediately life threatening to a firefighter wearing a structural firefighting ensemble (including breathing apparatus). National Institute of Standards and Technology (NIST) experiments in a single compartment show post flashover gas temperatures in excess of 1000o C (1832o F) and heat flux at the floor may exceed 170 kW/m2 (Donnelly, Davis, Lawson, & Selpak, 2006). Post flashover conditions in larger buildings with more substantial fuel load may be more severe!

Figure 11 integrates temperature, velocity, and oxygen concentration data from the simulation (Figures 3-10). Detail and accuracy is sacrificed to some extent in order to provide a (somewhat) simpler view of conditions at 200 seconds into the simulation (approximately 00:27 incident time). Note that as in individual slices, data is presented as a range due to uncertainty in the computer model.

Alternative Model

In addition to modeling fire dynamics based on incident conditions and tactical operations as they occurred, NIST also modeled the incident with a slightly different ventilation profile.

The basic input for the alternate simulation was the same as the simulation of actual incident conditions. Ventilation openings and timing was the same, with one exception; the sliding glass door on Floor 1, Side C was opened at 120 s into the simulation. Conditions in the basement during the alternative simulation were similar to the first. However, on Floor 1, the increase in ventilation provided by the sliding glass door on Side C resulted in a shallower hot gas layer and cooler conditions at floor level. A side-by-side comparison of the temperature gradients in these two simulations is provided in Figure 13.

Figure 13. Comparison of Temperature Gradients Along Centerline of Basement Stairwell (S2) at 200 s

stairwell_slice_comparison_sr1

Note: Adapted from Simulation of the Dynamics of the Fire at 3146 Cherry Road NE Washington D.C., May 30, 1999, NISTR 6510 (p. 21 & 27) by Dan Madrzykowski and Robert Vettori, 2000, Gaithersburg, MD: National Institute for Standards and Technology.

The NIST Report (Madrzykowski & Vettori, 2000) identified that the significant difference between these two simulations is in the region close to the floor. In the alternative simulation (Floor 1, Side C Sliding Glass Door Open) between the doorway to the basement and the sofa, the temperatures from approximately 0.6 m (2 ft) above the floor, to floor level are in the range of 20 C to 100 C (68F to 212 F), providing at least an 80 C (176 F) temperature reduction.

While this is a considerable reduction in gas temperature, it is essential to also consider radiant heat flux from the hot gas layer. Given the temperature of the hot gases from the ceiling level to a depth of approximately 3′ (0.9 m), the heat flux at the floor would likely have been in the range of 15-20 kW/m2 (or greater).

Questions

  1. Temperatures vary widely at a given elevation above the floor. Consider the slices illustrated in Figures 3, 6, and 9, and identify factors that may have influenced these major differences in temperature.
  2. How might the variations in temperature illustrated in Figures 3, 6, and9 and location of Firefighters Phillips (basement doorway), Mathews (living room, C/D corner), and Morgan (between Phillips & Mathews) have influenced their injuries?
  3. Examine the velocity of gas movement illustrated in Figures 4, 7, and 10 and integrated illustration conditions in Figure 11. How does this correlate to the photos in Figure 1 illustrating incident conditions at approximately 00:28?
  4. Explain how the size and configuration of ventilation openings resulted in a bi-directional air track at the basement door on Side C.
  5. How did the velocity of hot gases in the stairwell and living room influence the thermal insult to Firefighters Phillips, Mathews, and Morgan? What factors caused the high velocity flow of gases from the basement stairwell doorway into the living room?
  6. Rescue 1B noted that the floor in the living room was soft while conducting primary search at approximately 00:30. Why didn’t the parallel chord trusses in the basement fail sooner? Is there a potential relationship between fire behavior and performance of the engineered floor support system in this incident?
  7. How might stability of the engineered floor support system have differed if the sliding glass door in the basement had failed prior to the fire departments arrival? Why?
  8. How might the double pane glazing on the windows and sliding glass doors have influenced fire development in the basement? How might fire development differed if these building openings had been fitted with single pane glazing?
  9. What was the likely influence of turbulence in the flow of hot gases and cooler air on combustion in the basement? What factors influenced this turbulence (examine Figures 4, 7, and 10) illustrating velocity of flow and floor plan illustrated in conjunction with the second question)?
  10. How did conditions in the area in which Firefighters Phillips, Mathews, and Morgan were located correlate to the thermal exposure limits defined in Figure 12? How did this change in the alternate scenario? Remember to consider both temperature and heat flux.

Extended Learning Activity

The Cherry Road case study provides an excellent opportunity to develop an understanding of the influence of building factors, burning regime, ventilation, and tactical operations on fire behavior. These lessons can be extended by comparing and contrasting this case with other cases such as the 1999 residential fire in Keokuk, Iowa that took the lives Assistant Chief Dave McNally, Firefighter Jason Bitting, and Firefighter Nathan Tuck along with three young children. For information on this incident see NIOSH Death in the Line of Duty Report F2000-4, NIST report Simulation of the Dynamics of a Fire in a Two Story Duplex, NIST IR 6923.and video animation of Smokeview output from modeling of this incident

Master Your Craft

Ed Hartin, MS, EFO, MIFireE, CFO

References

District of Columbia (DC) Fire & EMS. (2000). Report from the reconstruction committee: Fire at 3146 Cherry Road NE, Washington DC, May 30, 1999. Washington, DC: Author.

Madrzykowski, D. & Vettori, R. (2000). Simulation of the Dynamics of the Fire at 3146 Cherry Road NE Washington D.C., May 30, 1999, NISTR 6510. August 31, 2009 from http://fire.nist.gov/CDPUBS/NISTIR_6510/6510c.pdf

National Institute for Occupational Safety and Health (NIOSH). (1999). Death in the line of duty, Report 99-21. Retrieved August 31, 2009 from http://www.cdc.gov/niosh/fire/reports/face9921.html

Townhouse Fire: Washington, DC:
Computer Modeling

Monday, September 28th, 2009

This post continues study of an incident in a townhouse style apartment building in Washington, DC with examination of the extreme fire behavior that took the lives of Firefighters Anthony Phillips and Louis Mathews.

A Quick Review

Prior posts in this series, Fire Behavior Case Study of a Townhouse Fire: Washington, DC, Townhouse Fire: Washington, DC-What Happened,and Townhouse Fire: Washington, DC-Extreme Fire Behavior examined the building and initial tactical operations at this incident. The fire occurred in the basement of a two-story, middle of building, townhouse apartment with a daylight basement. This configuration provided at grade entrances to Floor 1 on Side A and the Basement on Side C.

Engine 26, the first arriving unit reported heavy smoke showing from Side A and observed a bi-directional air track at the open front door. Engines 26 and 10 operating from Side A deployed hoselines into the first floor to locate the fire. Engine 17, the second due engine, was stretching a hoseline to Side C, but had insufficient hose and needed to extend their line. Truck 4, the second due truck, operating from Side C opened a sliding glass door to the basement to conduct search and access the upper floors (prior to Engine 17’s line being in position). When the door on Side C was opened, Truck 4 observed a strong inward air track. As Engine 17 reached Side C (shortly after Rescue 1 and a member of Truck 4 entered the basement) and asked for their line to be charged. Engine 17 advised Command that the fire was small.

Conditions changed quickly after the door on Side C was opened, as conditions in the basement rapidly transitioned to a fully developed fire with hot gases and flames extending up the interior stairway trapping Firefighters Phillips, Mathews, and Morgan. Confusion about building configuration (particularly the number of floors and location of entry points on Side A and C) delayed fire attack due to concern for opposing hoselines.

Modeling of the Cherry Road Incident

National Institute for Standards and Technology (NIST) performed a computer model of fire dynamics in the fire at 3146 Cherry Road (Madrzykowski and Vettori, 2000) using the NIST Fire Dynamics Simulator (FDS) software. This is one of the first cases where FDS was used in forensic fire scene reconstruction.

Fire Modeling

Fire modeling is a useful tool in research, engineering, fire investigation, and learning about fire dynamics. However, effective use of this tool and the information it provides requires understanding of its capabilities and limitations.

Models, such as the National Institute of Standards and Technology (NIST) Fire Dynamics Simulator (FDS) relay on computational fluid dynamics (CFD). CFD models define the fire environment by dividing it into small, rectangular cells. The model simultaneously solves mathematical equations for combustion, heat transfer, and mass transport within and between cells. When used with a graphical interface such as NIST Smokeview, output can be displayed in a three-dimensional (3D) visual format.

Models must be validated to determine how closely they match reality. In large part this requires comparison of model output to full scale fire tests under controlled conditions. When used for forensic fire scene reconstruction, it may not be feasible to recreate the fire to test the model. In these situations, model output is compared to physical evidence and interview data to determine how closely key aspects of model output matched events as they occurred. If model output reasonably matches events as they occurred, it is likely to be useful in understanding the fire dynamics involved in the incident.

It is crucial to bear in mind that fire models do not provide a reconstruction of the reality of an event. They are simplified representation of reality that will always suffer from a certain lack of accuracy and precision. Under the condition that the user is fully aware of this status and has an extensive knowledge of the principles of the models, their functioning, their limitations and the significance attributed to their results, fire modeling becomes a very powerful tool (Delemont & Martin, J., 2007, p. 134).

FDS output included data on heat release rate, temperature, oxygen concentration, and velocity of gas (smoke and air) movement within the townhouse. As indicated above, model output is an approximation of actual incident conditions.

In large scale fire tests (McGrattan, Hamins, & Stroup, 1998, as cited in Madrzykowski and Vettori, 2000), FDS temperature predictions were found to be within 15% of the measured temperatures and FDS heat release rates were predicted to within 20% of the measured values. For relatively simple fire driven flows such as buoyant plumes and flows through doorways, FDS predictions are within experimental uncertancies (McGrattan, Baum, & Rehm, 1998, as cited in Madrzykowski and Vettori, 2000).

Results presented in the NIST report on the fire at 3146 Cherry Road were presented as ranges to account for potential variation between model output and actual incident conditions.

Heat release rate is dependent on the characteristics and configuration of the fuel packages involved and available oxygen. In a compartment fire, available oxygen is dependent on the ventilation profile (i.e., size and location of compartment openings). The ventilation profile can change over time due to the effects of the fire (e.g., failure of window glazing) as well as human action (i.e., doors left open by exiting occupants, tactical ventilation, and tactical anti-ventilation)

In this incident there were a number of changes to the ventilation profile. Most significant of which were, 1) the occupant opened the second floor windows on Side C (see Figure 3), 2) the occupant left the front door open as they exited (see Figures 1 &2 ), 3) tactical ventilation of the first floor window on Side A, and opening of the sliding glass door in the basement on Side C (see Figures 1-3). In addition, the open door in the basement stairwell and open stairwell between the Floors 1 and 2 also influenced the ventilation profile (see Figure 1).

Figure 1. Cross Section of 3146 Cherry Road NE

cherry_road_cross_section

Figure 2. Side A 3146 Cherry Road NE

side_a_post_fire

Figure 3. Side C 3146 Cherry Road NE

side_c_post_fire

Figure 4 illustrates the timing of changes to the ventilation profile and resulting influence on heat release rate in modeling this incident. A small fire with a specific heat release rate (HRR) was used to start fire growth in the FDS simulation. In the actual incident it may have taken hours for the fire to develop flaming combustion and progression into the growth stage. Direct comparison between the simulation and incident conditions began at 100 seconds into the simulation which corresponds to approximately 00:25 during the incident.

Figure 4. FDS Heat Release Rate Curve

cherry_road_hrr_curve

Note: Adapted from Simulation of the Dynamics of the Fire at 3146 Cherry Road NE Washington D.C., May 30, 1999, NISTR 6510 (p. 14) by Dan Madrzykowski and Robert Vettori, 2000, Gaithersburg, MD: National Institute for Standards and Technology.

Questions

The following questions are based on heat release rate data from the FDS model presented in Figure 4.

  1. What was the relationship between changes in ventilation profile and heat release rate?
  2. What would explain the rapid increase in heat release rate after the right side of the basement sliding glass door is opened?
  3. Why might the heat release rate have dropped slightly prior to opening of the left side of the basement sliding glass door?
  4. Why did the heat release rate again increase rapidly to in excess of 10 MW after the left side of the basement sliding glass door was opened?
  5. How does data from the FDS model correlate to the narrative description of events presented in prior posts about this incident (Fire Behavior Case Study of a Townhouse Fire: Washington, DC, Townhouse Fire: Washington, DC-What Happened,and Townhouse Fire: Washington, DC-Extreme Fire Behavior)?

More to Follow

In addition to heat release rate data the computer modeling of this incident provided data on temperature, oxygen concentration, and gas velocity. Visual presentation of this data provides a more detailed look at potential conditions inside the townhouse during the fire. The next post in this series will present and examine graphic output from Smokeview to aid in understanding the fire dynamics and thermal environment encountered during this incident.

Master Your Craft

Ed Hartin, MS, EFO, MIFireE, CFO

References

District of Columbia (DC) Fire & EMS. (2000). Report from the reconstruction committee: Fire at 3146 Cherry Road NE, Washington DC, May 30, 1999. Washington, DC: Author.

Madrzykowski, D. & Vettori, R. (2000). Simulation of the Dynamics of the Fire at 3146 Cherry Road NE Washington D.C., May 30, 1999, NISTR 6510. August 31, 2009 from http://fire.nist.gov/CDPUBS/NISTIR_6510/6510c.pdf

National Institute for Occupational Safety and Health (NIOSH). (1999). Death in the line of duty, Report 99-21. Retrieved August 31, 2009 from http://www.cdc.gov/niosh/fire/reports/face9921.html