Posts Tagged ‘NIOSH’

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.

propranolol and hair loss 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

Wind Driven Fires

Sunday, February 26th, 2012

Seven Firefighters Injured

Seven firefighters were tragically injured in Prince George’s County Maryland on Friday, February 24, 2012. The fire broke out in the basement of a single-family, one-story house located at 6404 57th Avenue in Riverdale, MD shortly after 21:00 hours.

Note: View from Alpha-Bravo Corner street side. Photo by Billy McNeel.

On arrival, Engine 807B reported a two-story, single family dwelling with fire showing from the basement level on Side Bravo. Seven members from Companies 807 (Riverdale) and 809 (Bladensburg) entered Floor 1 of the building on Side A (East Side) and within eight seconds were enveloped by untenable, wind driven fire conditions. Preliminary reports indicate that firefighters had initiated an interior attack on the fire when a sudden rush of air, fanned by high winds, entered from the rear of the house either from a door or window being opened or broken out. (Brady, 2012). A report on Monday, February 27 indicated that some of the firefighters ran to the back of the one-story home, then entered through a basement door while other members of their company opened the front door in search of a victim (FirefighterNation, 2012).

In a statement to Washington Post reporter J. Freedom du Lac (2012), Chief Marc Bashoor indicated that strong winds were gusting out of the west at up to 40, 45 mph, blowing directly into the burning basement, which had a west-facing door. “As soon as the guys opened the front door and advanced, it blew from the basement, up the steps and right out the front door,” Bashoor said. “It was like a blowtorch coming up the steps and out the door… Without that wind, the hot air and gases would have been venting out of the rear of the house,” he said. “The current of air essentially produced a chimney right up the steps and out the front door.” (Washington Post, 2012).

Firefighters Ethan Sorrell and Kevin O’Toole from Bladensburg Volunteer Fire Department remain in critical condition at Washington Hospital Center. Riverdale Volunteer, Michael McLary also remains hospitalized for injuries. The other injured firefighters were released and sent home Saturday evening according to the latest reports.

The wind-fueled fireball that injured seven Prince George’s County firefighters when it blew through the burning house they had just entered was “a freak occurrence,” a department spokesman, Mark Brady, said Saturday (du Lac, 2012).

Chris Naum at Command Safety has an excellent post examining the fire building and weather conditions at the time of the incident. See Residential Fire Injures Seven Firefighters: Wind Driven Conditions Suspected.

Freak Occurrence?

Dealing with an accident involving a serious injury or fatality is extremely difficult, particularly when the complete circumstances and eventual outcome is unknown. What may appear to be obvious in retrospect may also have been not so clear to the individuals engaged in emergency operations. However, one might ask if the fire behavior encountered at 6404 57th Avenue in Riverdale, MD was in fact a freak occurrence. A freak is defined as a thing or occurrence that is abnormal, markedly unusual or irregular.

The conditions encountered were markedly different than usually encountered in fires occurring in single family dwellings. However, the conditions described in this incident are not unusual when considered in light of the building configuration and wind conditions at the time of the incident. Wind, flow path, and burning regime (fuel or ventilation controlled) have a tremendous impact on fire behavior and potential for rapid fire progression resulting in untenable conditions.

Wind Driven Fires

On April 16, 2007 Technician Kyle Wilson of the Prince William Fire & Rescue lost his life in a wind driven fire occurring in a large, single family dwelling. In the introduction to the investigative report produced by Prince William Fire & Rescue examining this incident, Chief Kevin J. McGee states:

First, the impact the wind had on this event was significant. While weather conditions, and specifically wind, are often discussed in the firefighting environment of wildland fires, it does not receive the same attention and consideration in structure fires. This incident showed the dramatic and devastating effect the wind can have on the spread of fire in a building. The wind forced the fire into the building and caused the sudden change in fire conditions inside, including the “blowtorch” effect witnessed by the crews on the scene (Prince William County Fire Rescue, 2008)

In January, the National Institute of Standards and Technology (NIST) released Simulation of the Dynamics of a Wind-Driven Fire in a Ranch-Style House-Texas (Barowy & Madrzykowski, 2012) examining fire behavior in the incident that took the lives of Houston Fire Department Captain James Harlow and Firefighter Damion Hobbs on April 12, 2009 while engaged in firefighting operations in a single family dwelling. This report emphasized that potential for wind driven fire conditions can occur in all types of buildings, including single-family residential structures.

NIST research (Madrzykowski & Kerber.(2009a, 2009b) has identified that wind driven fire conditions can be created with wind speeds as low as 4.5 m/s (10 mph) and that while structural fire departments have recognized the impact of wind on fire behavior, in general, standard operating guidelines (SOG) have not changed to address the risk of wind driven fires (Barowy & Madrzykowski, 2012).

Previous posts have examined NISTs research on the issue of wind driven fires:

Flow Path

On May 30, 1999, Firefighters Anthony Phillips and Louis Matthews of the District of Columbia Fire Department (DCFD) died and two others were severely injured as a result of rapid fire progression while engaged in firefighting operations at 3146 Cherry Road, NE. The fire occurred in the basement of a two-story, middle of building, townhouse apartment. Crews entered on Floor 1, Side A and were caught in the flow path of hot smoke and flames when a sliding glass door was opened at the Basement Level on Side C. Previous posts examined this incident in detail:

More recently, the City of San Francisco Fire Department released an investigative report examining the circumstances surrounding the deaths of Lieutenant Vincent Perez and Firefighter/Paramedic Anthony Valerio on June 2, 2011 while operating at a fire in the basement of a two story home with two levels below grade. Failure of a basement window placed the Lieutenant and Firefighter in the flow path between the basement window and their entry point on Floor 1. The investigative report produced by the San Francisco Fire Department details their findings and recommendations related to this incident.

Safety Investigation Report Line-of-Duty Deaths, 133 Berkley Way, June 2, 2011, Box 8155, Incident #11050532

Structural Firefighting Under Wind Conditions

Research and fireground experience point to the following:

  • Building configuration including windows, doors, and open interior stairways can have a significant impact on development of a flow path from the fire to one or more exhaust points.
  • Introduction of additional air to a ventilation controlled fire (without concurrent fire suppression) will quickly result in increased heat release rate.
  • Creation of openings at and above the fire level which result in a flow path with an exhaust opening above the inlet will result in a rapid increase in heat release rate.
  • Thermal conditions in the flow path above the fire and/or downstream from the fire location or will quickly become untenable.
  • Even limited wind conditions can result in wind driven fire conditions.
  • These factors in combination are even more likely to result in rapid fire progression and untenable conditions in the downstream flow path.

It is essential that Firefighters and Fire Officers recognize the influence of ventilation on fire behavior and potential for wind driven fire conditions and adjust their strategies and tactics accordingly. The following guidance is based on recommendations developed through the NIST wind driven fires research as well as data from National Institute for Occupational Safety and Health (NIOSH) death in the line of duty reports and incident investigative reports by the Texas State Fire Marshals Office.

Potential for wind driven conditions increases directly with wind speed. When wind speeds exceed a gentle breeze (8-12 mph) consider the potential for wind driven fire conditions and apply the following strategic and tactical considerations (CWIFR District Board, 2011):

  • If potential for wind driven fire conditions is identified, this should be communicated to all companies and members working at the incident as a safety message.
  • When possible, operate from the exterior and apply water from upwind directly into the involved compartments prior to interior attack. Even low flow exterior streams applied from upwind can have a significant impact on controlling the fire prior to interior operations).
  • In a wind-driven fire, it is most important to use the wind to your advantage and attack the fire from the upwind side of the structure, especially if the upwind side is the burned side. Note that this may be contrary to conventional offensive tactics that place hoselines between the hazard presented by the fire and potential occupants and uninvolved property.
  • Avoid pressurization of the building without first establishing adequate exhaust openings (2-3 times larger than the inlet). Remember that wind can create the same (or greater) positive pressure as a blower used in positive pressure ventilation (PPV). Pressurization without adequate exhaust can result in extreme fire behavior. Note: This is particularly important when the fire is on the leeward (downwind) side of the building and entry is made from the windward (upwind) side of the building.
  • Consider controlling the flow path by using anti-ventilation such as door control and limiting the use of (horizontal and vertical) tactical ventilation prior to fire control. However, it is essential to remember that unplanned ventilation resulting from fire effects can have a significant impact on the ventilation profile and subsequent flow path(s).
  • Avoid working in the exhaust portion of the flow path (between the fire and exhaust opening) or potential flow paths (between the fire and potential exhaust openings). Unplanned ventilation from fire effects can suddenly change the interior thermal conditions.
  • Identify potential refuge areas, escape routes, and safety zones prior to and during interior operations. Taking refuge in a compartment with an intact and closed door may temporarily provide tenable conditions and a place of refuge until the fire can be controlled or another avenue of egress established.

References & Additional Reading

Brady, M. (2012). Seven firefighters injured battling Riverdale house fire. Retrieved February 26, 2012 from http://pgfdpio.blogspot.com/2012/02/seven-firefighters-injured-battling.html

Central Whidbey Island Fire & Rescue (CWIFR) District Board. (2011). Board minutes February 9, 2012. Coupeville, WA: Author. [Adoption of Purpose, Policy, and Scope of SOG 4.3.6 Structural Firefighting Under Wind Conditions]

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.

du Lac, J. (2012). Blaze that injured 7 Prince George’s firefighters called ‘freak occurrence’. Retrieved February 26, 2012 from http://www.washingtonpost.com/local/blaze-that-injured-7-prince-georges-firefighters-called-freak-occurrence/2012/02/25/gIQAdGJMaR_story.html?hpid=z3

FirefighterNation. (2012). Critically burned in Maryland house fire, firefighters face long recovery. Retrieved February 28, 2012, from http://www.firefighternation.com/article/news-2/critically-burned-maryland-house-fire-firefighters-face-lengthy-recovery.

Madrzykowski , D. &  Barowy, A. (2012). Simulation of the dynamics of a wind-driven fire in a ranch-style house – Texas, TN 1729. Retrieved February 8, 2012 from http://www.nist.gov/customcf/get_pdf.cfm?pub_id=909779

Madrzykowski, D & Kerber, S. (2009a). Fire fighting tactics under wind driven conditions: Laboratory experiments, TN 1618. Retrieved February 8, 2012 from http://fire.nist.gov/bfrlpubs/fire09/PDF/f09002.pdf

Madrzykowski, D & Kerber, S. (2009b). Fire fighting tactics under wind driven fire conditions: 7-story building experiments, TN 1629. Retrieved February 8, 2012 from http://fire.nist.gov/bfrlpubs/fire09/PDF/f09015.pdf

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 Occpational Safety and Health (NIOSH). (2008). Death in the line of duty…2007-12. Retrieved February 9, 2012 from http://www.cdc.gov/niosh/fire/pdfs/face200712.pdf

National Institute for Occpational Safety and Health (NIOSH). (2009). Death in the line of duty…2009-11. Retrieved February 9, 2012 from http://www.cdc.gov/niosh/fire/pdfs/face200911.pdf

National Institute for Occpational Safety and Health (NIOSH). (2009). Death in the line of duty…2007-29. Retrieved February 9, 2012 from http://www.cdc.gov/niosh/fire/reports/face200729.html

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

Prince William County Department of Fire & Rescue. (2007). Line of duty death investigative report. Retrieved February 9, 2012 from http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&ved=0CCgQFjAB&url=http%3A%2F%2Fwww.iaff.org%2Fhs%2FLODD_Manual%2FLODD%2520Reports%2FPrince%2520William%2520County%2C%2520VA%2520-%2520Wilson.pdf&ei=b3dKT8LyGfHSiALt5tnrDQ&usg=AFQjCNFBBTfVkWIREXw0-wbd978fWSoP8w&sig2=y6_OEeJvhFSggiKioMESaw

San Francisco Fire Department. (2012). Safety Investigation Report Line-of-Duty Deaths, 133 Berkley Way, June 2, 2011, Box 8155, Incident #11050532 Retrieved February 26, 2012 from http://statter911.com/files/2012/02/Safety-Investigation-133-Berkeley-Way-Printable.pdf

Texas State Fire Marshal’s Office. (2007). Firefighter fatality investigation, Investigation Number FY 07-02. http://www.tdi.texas.gov/reports/fire/documents/fmloddnoonday.pdf

Texas State Fire Marshal’s Office. (2009). Firefighter fatality investigation, Investigation Number FY 09- http://www.tdi.texas.gov/reports/fire/documents/fmloddhouston09.pdf

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

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).

NIOSH F2009-11: The Minority Report

Tuesday, May 4th, 2010

As a critical friend of the NIOSH Firefighter Fatality Investigation and Prevention Program, I have provided testimony at public hearings and engaged in discussions with NIOSH staff regarding improvement of the quality of information provided in Death in the Line of Duty Reports, particularly in incidents involving extreme fire behavior. In addition, I have provided expert review on a number of Death in the Line of Duty Reports (including F2009-11). The discussion of fire dynamics, fire behavior indicators, and influence of ventilation and wind effects in Report F2009-11 is evidence that this feedback has been heard! I would like to thank Tim Merinar and the other NIOSH staff for their efforts in this area.

However, more work is needed. Just over a year ago, I read a news report about the deaths of Captain James Harlow and Firefighter Damion Hobbs of the Houston Fire Department during operations at a residential fire. I recalled Houston had seen a number of fatalities during structural firefighting over a reasonably short period of time. Curious, I reviewed reports on these incidents developed by NIOSH and the Texas State Fire Marshals Office. Seeing some commonality in the circumstances surrounding these incidents, I called a colleague at NIOSH and recommended that the investigation of the incident in which Captain Harlow and Firefighter Hobbs lost their lives, include review of prior incidents (and near miss data if available) to identify underlying causal or contributing factors that may not be evident from examination of a single incident.

While we often want to know the cause of a tragic event, the reality is that it is often much more complicated that we would like. Investigative reports such as those prepared by NIOSH focus a bright light on the what and how, but often leave the question of why hidden in the shadows. Observations and questions in this post are not presented as an indictment of the Houston Fire Department, or to question the commitment and bravery of Captain Harlow and Firefighter Hobbs, but simply to encourage each and every one of us to look more deeply; more deeply at our profession, at our own organizations, and at ourselves.

Epidemiology

Epidemiology is the study of factors affecting the health and illness of populations. Epidemiological research is the foundation of public health intervention and preventative medicine. This research is focused at identifying relationships between exposures and disease or death. Identification of causal relationships between exposures and outcomes is critical. However, correlation does not determine cause, and identification of causality is often complex and tentative.

For the fire service, epidemiological study has and continues to focus on heart disease, stress, and cancer (see USFA, NIOSH Launch Cancer Study). However, these same concepts can be applied to traumatic fatalities as well.

R-Fire 7811 Oak Vista, Houston TX

On April 12, 2009 Captain James Harlow and Firefighter Damion Hobbs lost their lives in a residential fire at 7811 Oak Vista in Houston, Texas. On April 9, 2010, the National Institute for Occupational Safety and Health released Death in the Line of Duty Report F2009-11 summarizing their investigation of this incident. Overall, this report is well written and provides an excellent examination of the events involved in this incident. The Texas State Fire Marshals Office also conducted an investigation of this incident and released a report a short time prior to release of NIOSH Report F2009-11.

Contributing Factors

NIOSH identified eight items as key contributing factors in the deaths of Captain Harlow and Firefighter Hobbs:

  • An inadequate size-up prior to committing to tactical operations
  • Lack of understanding of fire behavior and fire dynamics
  • Fire in a void space burning in a ventilation controlled regime
  • High winds
  • Uncoordinated tactical operations, in particular fire control and tactical ventilation
  • Failure to protect the means of egress with a backup hose line
  • Inadequate fireground communications
  • Failure to react appropriately to deteriorating conditions.

What is missing from this list? Six of the seven items on this list relate to human action or inaction. The report points out the need for policy, procedures, and additional training to address the contributing factors. While this is undoubtedly necessary, does this provide the entire answer?

The Remaining Question

As with all NIOSH firefighter fatality investigations, the focus of this report is on the circumstances and events surrounding a single incident. In this report, there is a brief mention of investigation of the deaths of other firefighters from this department, but no analysis of commonality or underlying contributing factors is provided. This leaves the question, to what extent did organizational culture impact on the circumstances and events involved in this tragic incident?

In his keynote presentation at the 2010 Fire Department Instructors Conference, Lieutenant Frank Ricci of the New Haven (CT) Fire Department indicated that the culture of the fire service is wrongly blamed for many of its problems. Lieutenant Ricci indicated that a large percentage of firefighter injuries and deaths are not due to inherent risks, but to an unwillingness to take personal responsibility for safety (Thompson, 2010). I would ask, why are firefighters unwilling to take personal responsibility? What factors influence this pattern of behavior? I suspect that it is our unquestioned assumptions about the way that things are (part of our culture). In this sense, culture is not to blame, but is simply one of a number of contributing and causal factors in many firefighter fatalities.

Common Elements

A cursory examination of the facts presented in the reports of NIOSH investigation of traumatic fatalities in the Houston Fire Department since 2000 shows a distinct pattern. Each of the fatalities involved members of the first arriving company where a fast attack was initiated without adequate size up and in most (and likely all) cases failure to assess risk versus gain. A more detailed examination of these events would likely provide a more finely grained picture of organizational expectations that make extremely aggressive fire attack without adequate size-up and risk assessment the norm, rather than the exception.

Table 1. Traumatic Line-of-Duty-Deaths in Houston, Texas 2000-2009

Report Event Type Commonality
F2000-13 Collapse (2 LODD)
Commercial Fire-Collapse
Victims were part of first in company

Inadequate size-up

Failure to assess risk versus gain

F2001-33 Rapid Fire Progress (1 LODD)
High-Rise Apartment Fire-Wind Driven Fire
Victim was part of the first in company

Inadequate size-up (consideration of wind)

F2004-14 Rapid Fire Progress (1 LODD)
Commercial Fire-Disorientation Subsequent to Rapid Fire Progress
Victim was part of the first in company

Inadequate size-up

Failure to assess risk versus gain

F2005-09 Collapse & Rapid Fire Progress (1 LODD) Residential Fire (Vacant)-Rapid Collapse Subsequent to Fire Progress Victim was part of the first in company

Inadequate size-up

Failure to assess risk versus gain

F2009-11 Rapid Fire Progress (2 LODD) Residential Fire-Wind Driven Fire Victim was part of the first in company

Inadequate size-up

Failure to assess risk versus gain

A Comparison

On September 11, 1991, Continental Express Flight 2574 crashed in Eagle Lake Texas killing all 14 people aboard. As with all commercial aircraft accidents, this incident was investigated by the National Transportation Safety Board. The board identified the cause as failure of maintenance and inspection personnel to adhere to proper maintenance and quality assurance procedures. However, the board also identified failure of management to ensure compliance with approved procedures and failure of Federal Aviation Administration to detect and correct this problem as contributing factors. Board member John K. Lauber, filed a dissenting statement. It is clear based on this record alone, that the series of failures which led directly to the accident were not the result of an aberration, but rather resulted from the normal accepted way of doing business at Continental Express (NTSB, 1992, p. 53). Lauber advocated restating the probable cause of this accident as the failure of Continental Express management to establish a corporate culture which encouraged and enforced adherence to approved maintenance and quality assurance procedures (NTSB, 1992, p. 54).

It is essential to look at the five events identified in reports F2000-13, F2001-33, F2004-14, F2005-09, and F2009-11 (NIOSH, 2001, 2002, 2005a, 2005b, 2010) from a longitudinal perspective to identify in greater detail and understand the common elements and potential systemic cultural issues that influenced the actions of those involved. While the influence of organizational culture is more difficult to identify than failure to comply with good practice, failure to recognize a hazardous condition, or an error in decision-making, it has a far more pervasive influence on fire fighter safety than these specific, individual acts.

Based on limited research, it is apparent that the Houston Fire Department (like many others) places an extremely high value on rapid and aggressive offensive firefighting operations. While the outcome of this incident resulted from a wide range of interrelated contributing factors, organizational culture and lack of knowledge regarding fire behavior and the influence of tactical operations were likely the most significant.

Identification of organizational culture as a contributing factor in this incident is based on data included in the DRAFT report as well as review of NIOSH Reports F2000-13, F2001-33, F-2004-14, F2005-09, and F2009-11 (NIOSH, 2001, 2002, 2005a, 2005b, 2010) as well as review of the Houston Fire Department Strategic Plan FY2008-2012 (n.d., HFD) and Philosophy of Firefighting (2003, HFD).

A memorandum from the Office of the Fire Chief defining the Houston Fire Departments philosophy of firefighting (HFD, 2003) after the McDonalds (NIOSH, 2001) and Four Leaf Tower (NIOSH, 2002) fires reinforced the importance of risk assessment in selecting strategies and tactics. In this memo, the chief identified the importance of organizational culture, stating we pride ourselves in being very aggressive interior fire fighters and look down on those that fight fire from the street (p. 1). While this memorandum was written in 2003, lack of adequate size up and risk assessment was a contributing factor in three incidents resulting in four line-of-duty deaths involving Houston Fire Department members in subsequent six years.

The Houston Fire Department Strategic Plan for FY2008-2012 (n.d., HFD) identifies safety as a core organizational value, stating: preservation of life remains the number one goal of the HFD beginning with the responder and extending to the public (p. 5). This focus continues with enhancement of the health and safety of HFD members as the first goal within the strategic plan. However, while the strategic plan provides a detailed blueprint for action, no objective or action plan element addresses the predominant contributory factors that are common in the seven line-of-duty deaths of Houston Fire Department members resulting from traumatic cause between 1999 and 2009. For example, Objective 1.5 of the strategic plan focuses on National Fallen Fire fighter Initiative #1 which states define and advocate the need for cultural change within the fire service relating to safety; incorporating leadership, management, supervision, accountability and personal responsibility (HFD, n.d., p. 8). However, the sub elements of this objective focus on near miss reporting, roadway emergency safety, and response to violent incidents.

In the incident that took the lives of Captain Harlow and Firefighter Hobbs, several elements point to the focus on speed and aggressive action. Despite his seniority and experience, the captain of the first arriving engine quickly initiated an interior attack without adequate size-up and risk assessment (or performed a size-up and failed to recognize critical fire behavior indicators). In addition, he left his portable radio on the apparatus, E-26s thermal imaging camera (TIC) was left outside the front door. Any one of these elements alone might indicate a simple error, but in combination along with the context provided by previous LODD incidents (NIOSH, 2001, 2002, 2005a, 2005b) this is likely evidence of the cultural value of speed and aggressive action over deliberate assessment of conditions and decision-making based on risk assessment.

While increased protection through the use of the reed hood has significant potential benefits (similar technology is used by the Swedish fire service), it is quite possible that this type of personal protective clothing (which is somewhat unique to the Houston Fire Department) is used to permit fire fighters to penetrate deeper into hostile environments, rather than simply to provide improved protection with the ordinary or hazardous range of conditions encountered during structural firefighting.

Recommendation

Based on these factors identified in NIOSH Report F2009-11 (2010) as well Reports F2000-13, F2001-33, F2004-14, F2005-09 (2001, 2002, 2005a, 2005b), I recommend that fire service organizations assess the impact of their organizational culture on fire fighter safety and operational performance.

Note that this recommendation is not simply focused on the Houston Fire Department. It is a global recommendation, that each of us examine the influence of culture within our respective organizations.

Ed Hartin, MS, EFO, MIFireE, CFO

References

Houston Fire Department. (2003) Philosophy of firefighting. Retrieved January 24, from http://www.houstontx.gov/fire/reports/philoff.pdf

Houston Fire Department. (n.d.) Houston Fire Department Strategic Plan FY2008-2012. Retrieved January 24 from http://www.houstontx.gov/fire/reports/SP0811.pdf

National Transportation Safety Board (NTSB). Aircraft accident report: Britt Airways, Inc. d/b/a/ Contenental Express Flight 2474 in flight structural breakup, EMB-120RT, N33701, Eagle Lake, Texas, September 11, 1991, NTSB/AAR-92/04. Washington, DC: Author.

National Institute for Occupational Safety and Health (NIOSH). (2001). Death in the line of duty, Report F2000-13. Retrieved January 24, 2010 from http://www.cdc.gov/niosh/fire/pdfs/face200013.pdf.

National Institute for Occupational Safety and Health (NIOSH). (2002). Death in the line of duty, Report F2001-33. Retrieved January 24, 2010 from http://www.cdc.gov/niosh/fire/pdfs/face200133.pdf.

National Institute for Occupational Safety and Health (NIOSH). (2005a). Death in the line of duty, Report F2004-14. Retrieved January 24, 2010 from http://www.cdc.gov/niosh/fire/pdfs/face200414.pdf.

National Institute for Occupational Safety and Health (NIOSH). (2005b). Death in the line of duty, Report F2005-09. Retrieved January 24, 2010 from http://www.cdc.gov/niosh/fire/pdfs/face200509.pdf.

National Institute for Occupational Safety and Health (NIOSH). (2010). Death in the line of duty, Report F2009-11. Retrieved April 25, 2010 from http://www.cdc.gov/niosh/fire/pdfs/face200911.pdf

Thompson, J. (2010) FDIC keynote: Fire service culture not to blame for problems. Retrieved May 3, 2010 from http://www.firerescue1.com/firefighter-safety/articles/810852-FDIC-keynote-Fire-service-culture-not-to-blame-for-problems/

Fully Developed Fires:
Key Fire Behavior Indicators

Thursday, October 22nd, 2009

This post continues examination of key indicators used to recognize stages of fire development (i.e., incipient, growth, fully developed, and decay), burning regimes (i.e., fuel and ventilation controlled) with a look at indicators of the fully developed stage of fire development. Most buildings are comprised of multiple, interconnected compartments and fire conditions can vary widely from compartment to compartment. Fire in the compartment of origin may have reached the fully developed stage, while adjacent compartments may have just entered the growth stage.

Figure 1. Fully Developed Fire

fully_developed_fire

National Institute for Occupational Safety and Health (NIOSH) Death in the Line of Duty Report F2007-02 (2009) recommends that fire service agencies: Train fire fighters to recognize the conditions that forewarn of a flashover/flameover [rollover] and communicate fire conditions to the incident commander as soon as possible (p. 2). Note: flameover and Rollover are synonyms.

Flameover (Rollover): The condition where unburned fuel (pyrolyzate) from the originating fire has accumulated in the ceiling layer to a sufficient concentration (i.e., at or above the lower flammable limit) that it ignites and burns; can occur without ignition of, or prior to, the ignition of other fuels separate from the origin. (NFPA 921, 2008, 3.3.67 and 3.3.137)

Recognition of key fire behavior indicators is critical. However, communication of this information to the incident commander (as it may impact on strategies) alone is not sufficient. Companies working in the fire environment must proactively mitigate this threat through effective fire control and ventilation strategies and tactics.

Flashover

Flashover is the sudden transition from a growth stage to fully developed fire. When flashover occurs, there is a rapid transition to a state of total surface involvement of all combustible material within the compartment. Conditions for flashover are defined in a variety of different ways. In general, ceiling temperature in the compartment must reach 500o-600o C (932o-1112o F) or the heat flux (a measure of heat transfer) to the floor of the compartment must reach 15-20 kW/m2 (1.32 Btu/s/ft2)-1.76 Btu/s/ft2). When flashover occurs, burning gases will push out openings in the compartment (such as a door leading to another room) at a substantial velocity (Karlsson & Quintiere, 2000).

It is important to remember that flashover does not always occur. There must be sufficient fuel and oxygen for the fire to reach flashover. If the initial object that is ignited does not contain sufficient energy (heat of combustion) and does not release it quickly enough (heat release rate), flashover will not occur (e.g., small trash can burning in the middle of a large room). Likewise, if the fire sufficiently depletes the available oxygen, heat release rate will drop and the fire in the compartment will not reach flashover (e.g., small room with sealed windows and the door closed). A fire that fails to reach a sufficient heat release rate for flashover to occur due to limited ventilation presents a significant hazard as increased ventilation may result in a ventilation induced flashover (see Understanding Flashover: Myths & Misconceptions Part 2 and The Ventilation Paradox).

Indicators of Flashover Potential

Recognizing flashover and understanding the mechanisms that cause this extreme fire behavior phenomenon is important. However, the ability to recognize key indicators and predict the probability of flashover is even more important. Indicators of potential or impending flashover are listed in Figure 2.

Figure 2. Indicators of Potential Flashover

flashover_indicators

If the fire in our residential scenario is nearing flashover (in the compartment of origin) what fire behavior indicators might be observed? Use the B-SAHF model to help you frame your answers.

You have responded to a fire in a one-story single family dwelling of wood frame construction. A fire which started in a bedroom on the Alpha Bravo corner of the structure is nearing flashover. A thick hot gas layer has developed in the bedroom and is flowing out the open door into the hallway. The fire has extended to the bed and flames in the plume have reached the ceiling and have begun to extend horizontally in the ceiling jet. Fuel packages below the level of the hot gas layer (e.g., furniture, carpet, and contents) are beginning to pyrolize.

  • What conditions would you expect to see from the exterior of the structure?
  • What indicators may be visible from the front door as you make entry?

Remember that fire conditions will vary throughout the building. While the fire is in the growth stage and nearing flashover in the bedroom, conditions may be different in other compartments within the building.

  • What indicators would you anticipate observing as you traveled through the living room to the hallway leading to the bedroom?
  • What conditions would you find in the hallway outside the fire compartment?
  • After making entry, consider if conditions are different than you anticipated?
  • Why might this be the case?
  • What differences in conditions would be cause for concern?
  • How might your answers to the preceding questions have differed if the bedroom door was closed and fire growth limited by ventilation?

Fully Developed Fire

At this post-flashover stage, energy release is at its greatest, but is generally limited by ventilation (more on this in a bit). Unburned gases accumulate at the ceiling level and frequently burn as they leave the compartment, resulting in flames showing from doors or windows. The average gas temperature within a compartment during a fully developed fire ranges from 700o-1200o C (1292o-2192o F)

Remember that the compartment where the fire started may reach the fully developed stage while other compartments have not yet become involved. Hot gases and flames extending from the involved compartment transfer heat to other fuel packages (e.g., contents, compartment linings, and structural materials) resulting in fire spread. Conditions can vary widely with a fully developed fire in one compartment, a growth stage fire in another, and an incipient fire in yet another. It is important to note that while a fire in an adjacent compartment may be incipient, conditions within the structure are immediately dangerous to life and health (IDLH).

Indicators of a Fully Developed Fire

Remember that a fully developed fire refers to conditions within a given compartment or compartments. It does not necessarily mean that the entire building is fully involved. Figure 3 lists indicators of fully developed fire conditions.

Figure 3. FBI-Fully Developed Stage

fully_developed_indicators

If the fire in our residential scenario has progressed to the fully developed stage (in the compartment of origin) what fire behavior indicators might be observed? Use the B-SAHF model to help you frame your answers.

You have responded to a fire in a one-story single family dwelling of wood frame construction. A fire which started in a bedroom on the Alpha Bravo corner of the structure has reached the fully developed stage and now involves the contents of the room and interior finish of this compartment.

  • What conditions would you expect to see from the exterior of the structure?
  • What indicators may be visible from the front door as you make entry?

Remember that fire conditions will vary throughout the building. While the fire is fully developed in the bedroom, conditions may be different in other compartments within the building.

  • What indicators would you anticipate observing as you traveled through the living room to the hallway leading to the bedroom?
  • What conditions would you find in the hallway outside the fire compartment?
  • After making entry, consider if conditions are different than you anticipated?
  • Why might this be the case?
  • What differences in conditions would be cause for concern?

Ventilation Controlled Fires

When the fire is burning in a ventilation controlled state, any increase in the supply of oxygen to the fire will result in an increase in heat release rate. Increase in ventilation may result from firefighters making entry into the building (the access point is a ventilation opening), tactical ventilation (performed by firefighters), or unplanned ventilation (e.g., failure of window glazing due to elevated temperature).

It is essential to recognize when the fire is, or may be ventilation controlled, and the influence of planned and unplanned changes in ventilation profile on fire behavior. Most compartment fires in the late growth stage or which are fully developed are ventilation controlled when the fire department arrives. Even if the fire has not entered the decay stage due to limited ventilation, the increased oxygen provided by increases in ventilation (such as that caused by opening the door to make entry) will increase heat release rate. This is not to say that increased ventilation is a bad thing, but firefighters should be prepared to deal with this change in fire behavior.

Master Your Craft

Remember the Past

Line of duty deaths involving extreme fire behavior has a significant impact on the family of the firefighter or firefighters involved as well as their department. Department investigative reports and NIOSH Death in the Line of Duty reports point out lessons learned from these tragic events. However, as time passes, these events fade from the memory of those not intimately connected with the individuals involved. It is important that we remember the lessons of the past as we continue our study of fire behavior and work to improve firefighter safety and effectiveness on the fireground.

October 29, 2008
Firefighter Adam Cody Renfroe
Crossville Fire Department, Alabama

The Crossville Fire Department was dispatched to a fire in a single-family residence. was on the first engine to arrive on the scene to find thick, black smoke from the roof and a report that all occupants were out of the house.

Firefighter Renfroe and another firefighter advanced a hoseline to the front door of the residence. He sent the other firefighter back to the fire truck for a tool. When the firefighter returned, Firefighter Renfroe was gone and the nozzle remained by the doorway. At about the same time, the fire inside of the structure intensified. Firefighter Renfroe transmitted a distress message from the interior. Firefighters were not immediately able to enter the structure due to fire conditions.

Firefighters discovered Firefighter Renfroe about 4 feet from the homes back door, but By the time firefighters reached him, he was deceased. The cause of death was smoke inhalation and thermal burns.

For more information on this incident, see NIOSH Death in the Line of Duty Report F2008-34.

Ed Hartin, MS, EFO, MIFireE, CFO

References

Karlson, B. & Quintiere, J. (2000) Enclosure fire dynamics. Boca Raton, FL: CRC Press.

National Institute for Occupational Safety and Health (NIOSH). (2009). Death in the Line of Duty Report F2007-02. Retrieved October 22, 2009 from http://www.cdc.gov/niosh/fire/pdfs/face200702.pdf .

Upcoming Events and Information

Monday, October 12th, 2009

Open Enrollment CFBT Level I & Instructor Courses

CFBT-US, LLC and the Northwest Association of Fire Trainers (NAFT) will be offering CFBT Level I and Instructor Courses at the Clackamas County (OR) Fire District I CFBT facility.

CFBT Level I
7-9 November 2009
Course Fee: $335

CFBT Instructor
9-13 November 2009
Course Fee: $915

Instructor course participants receive a copy of 3D Firefighting: Training, Techniques, & Tactics and an extensive 2-DVD library of CFBT resources including the CFBT Level I curriculum. For information on these courses download a NAFT CFBT Brochure and the CFBT Level I and CFBT Instructor Course Information Sheets.

CFBT Workshop in Sand, Sweden

From 12-16 October 2009, I will be participating in a CFBT workshop in Sand, Sweden along with a small group of instructors from around the world. We will be studying the compartment fire behavior curriculum at the Swedish Civil Contingencies Agency (Myndigheten fr samhllsskydd och beredskap (MSB)) College in Sand.

Figure 1. Fire Behavior Training in Sand

sando1

In January of 2009 MSB replaced the Swedish Rescue Services Agency, the Swedish Emergency Management Agency, and the Swedish National Board of Psychological Defense. The MSB maintains two fire service colleges, one in Sand (see Figure 2) and the other in Revinge.

Figure 2. MSB College in Sand

sando2

The International Conference of Fire and Rescue, Valdivia – Chile 2010 CIFR

My brothers with Company 1 Germania of the Valdivia, Chile Fire Department have taken on a tremendous task with delivery of the first International Conference of Fire & Rescue in Valdivia. The conference will be held 23-27 January 2010.

Conference presenters include a diverse cadre of instructors from around the world. I will be presenting a series of seminars on fire behavior as well as a hands-on CFBT workshop. Presentations will be simultaneously translated into English and Spanish (as applicable). Have a look at the Conference Web Site for more information on this tremendous learning opportunity.

NIOSH Death in the Line of Duty F2007-02

On November 23, 2006, Firefighter Steven Solomon, a 33-year-old career fire fighter was seriously injured during a ventilation induced flashover or related fire behavior event in an abandoned single story duplex in Atlanta, GA; he died as a result of these injuries 6 days later.

NOSH Report F2007-02 provides an excellent description of fire behavior indicators observed prior to the occurrence of extreme fire behavior and correctly identifies that increased ventilation without coordinated fire attack resulted in worsening fire conditions.

Several conclusions in the report were based on computational fluid dynamics (CFD) modeling using the National Institute of Standards and Technology (NIST) Fire Dynamics Simulator software. As discussed in a previous post computer modeling is an excellent tool, but it is important to understand both its capabilities and limitations (see Townhouse Fire-Washington, DC: Computer Modeling)

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).

Review NIOSH Report F2007-02 and see if you agree or disagree with the conclusions regarding the type of extreme fire behavior phenomena involved in this incident.

Ed Hartin, MS, EFO, MIFireE, CFO

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

Incipient Stage Fires:
Key Fire Behavior Indicators

Thursday, September 24th, 2009

Building Factors, Smoke, Air Track, Heat, and Flame (B-SAHF) are critical fire behavior indicators. Understanding the indicators is important, but more important is the ability to integrate these factors in the process of reading the fire as part of size-up and dynamic risk assessment.

This post reviews application of the B-SAHF organizing scheme to recognizing and identifying stages of fire development and burning regime.

Compartment Fire Development

Part of the process of reading the fire involves recognizing the stages of fire development and burning regime (e.g., fuel or ventilation controlled). Remember that fire conditions can vary considerably throughout the building with one compartment containing a fully developed fire, an adjacent compartment in the growth stage, and still other compartments yet uninvolved. Similarly, burning regime may vary from compartment to compartment. Recognizing the stages of fire development and burning regime allows firefighters to predict what is likely to happen next (if action is not taken), potential changes due to unplanned ventilation (such as failure of a window), and the likely effect of tactical action.

Compartment fire development can be described as being comprised of four stages: incipient, growth, fully developed and decay (see Figure 1). Flashover is not a stage of development, but simply a rapid transition between the growth and fully developed stages.

Figure 1. Heat Release Rate (HRR) and Fire Development

fire_development_curve_basic

Compartment fires do not always follow the simple, idealized fire development curve illustrated in Figure 1. The speed with which the fire develops, peak heat release rate, and duration of burning are dependent on both the characteristics of the fuel involved and ventilation profile (available oxygen).

Hazard of Ventilation Controlled Fires

Many if not most fires that have progressed beyond the incipient stage when the fire department arrives are ventilation controlled. This means that the heat release rate (the fire’s power) is limited by the ventilation profile, in particular, the existing openings.

If ventilation is increased, either through tactical action or unplanned ventilation resulting from effects of the fire (e.g., failure of a window) or human action (e.g., exiting civilians leaving a door open), heat release rate will increase, potentially resulting in a ventilation induced flashover as illustrated in Figure 2.

Figure 2. Ventilation Induced Flashover

vent_induced_flashover_curve

Incipient Stage

Going back to the basics of fire behavior, ignition requires heat, fuel, and oxygen. Once combustion begins, development of an incipient fire is largely dependent on the characteristics and configuration of the fuel involved (fuel controlled fire). Air in the compartment provides adequate oxygen to continue fire development. During this initial phase of fire development, radiant heat warms adjacent fuel and continues the process of pyrolysis. A plume of hot gases and flame rises from the fire and mixes with the cooler air within the room. This transfer of energy begins to increase the overall temperature in the room. As this plume reaches the ceiling, hot gases begin to spread horizontally across the ceiling. Transition beyond the incipient stage is difficult to define in precise terms. However, as flames near the ceiling, the layer of hot gases becomes more clearly defined and increase in volume, the fire has moved beyond its incipient phase and (given adequate oxygen) will continue to grow more quickly.

Depending on the size of the compartment and ventilation profile, there may only be a limited indication (or no indication at all) from the exterior of the building that an incipient stage fire is burning within. Incipient stage indicators are listed in Figure 3

Figure 3. B-SAHF Indicators of an Incipient Stage Fire

incipient_indicators

Application Exercise

Consider the following situation and how critical fire behavior indicators would present. Use the B-SAHF model to help you frame your answers.

You have responded to a fire in a one-story single family dwelling of wood frame construction. An incipient fire is burning in a bedroom on the Alpha Bravo corner of the structure. The fire is limited to a plastic trash can containing waste paper which is located next to the bed.

  • What conditions would you expect to see from the exterior of the structure?
  • What indicators may be visible from the front door as you make entry?
  • What might you observe traveling through the living room and down the hallway?
  • What conditions would you find in the bedroom?

It is essential to think about what you are likely to find inside when observing fire behavior indicators from the exterior and performing a risk assessment. After making entry, consider if conditions are different than you anticipated.

  • Why might this be the case?
  • What differences in conditions would be cause for concern?

Master Your Craft

More to Follow

The next post in this series will continue examination of the relationship between the B-SAHF indicators, fire development, and burning regime with a look at growth stage fires in both fuel and ventilation controlled burning regimes.

Ed Hartin, MS, EFO, MIFireE, CFO