Posts Tagged ‘firefighter LODD’

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.

face201228_Page_01

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.

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

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).

Hazards Above: Part 3

Sunday, July 25th, 2010

My last two posts (Hazards Above, Hazards Above: Part 2)examined a series of incidents involving firefighter injuries or near miss incidents involving fires occurring in or extending into void spaces in wood frame, residential structures. Yesterday, two members of the Bridgeport, Connecticut Fire Department lost their lives under similar circumstances.

Bridgeport, CT LODD

At 1553 hours on Saturday, July 24, 2010, the Bridgeport, Connecticut Fire Department was dispatched for a residential fire at 41 Elmwood Avenue. First arriving companies found heavy smoke from Floors 2 and 3 of a 2-1/2 story, wood frame, multi-family dwelling. Lieutenant Steven Velazquez and Firefighter Michael Baik were performing a search of the third floor when they transmitted a Mayday. Lieutenant Velazquez and Firefighter Baik were located on Floor 3 by the Rapid Intervention Team (RIT), but were not breathing and in cardiac arrest when removed from the building. CPR was initiated and they were transported to Bridgeport and St. Vincent’s Hospitals where they were pronounced dead.

More information on this tragic incident will be provided as it becomes available.

FBI and Ventilation Controlled Fires-the UL Experiments

As discussed in Hazards Above: Part 2, obvious smoke and air track indicators of a ventilation controlled fire may become diminished as the fire transitions from growth to decay stage. The decay stage ventilation controlled fire may present similar (but not identical) indicators to an incipient or early growth stage fire.

Underwriters Laboratories (UL) recently conducted a study of the effects of horizontal, natural ventilation on fires in residential structures (see Did You Ever Wonder. The results of this research will be released this fall along with a free on-line training program through UL University. During this research 15 experiments were conducted in two different residential structures. Fuel loading was consistent and the point of origin was a couch in the living room for each of the tests. The variable was the location, size, and sequence of horizontal ventilation. Interestingly, one observation remained remarkably consistent throughout the tests: Diminished smoke and air track indicators as the ventilation controlled fire transitioned from growth to decay stage. This is illustrated by a series of screen captures from video shot from Side A of the one-story structure used in these experiments.

Figure 1. Early Growth Stage

Figure 2. Growth Stage (Peak HRR Prior to Ventilation)

Figure 3. Decay Stage (Reduced HRR)

Figure 4. Conditions Immediately Following Ventilation (HRR Increasing)

Another commonality between each of the experiments was a fairly rapid and significant increase in HRR after ventilation was performed. In no case did ventilation (alone) improve conditions at any location or level inside the test buildings. Horizontal, natural ventilation (tactical or unplanned) with a delay in application of water to the seat of the fire will result in worsening conditions.

Situational Awareness

As illustrated in Figure 3, lack of obvious indicators can be deceptive. The structure used in the UL tests did not have normal window glazing as this would have resulted in less predictability in the exact location and sequence of ventilation. However, in an actual structure fire, observation of smoke conditions through windows, condensation on window glazing (incipient or early growth stage) and condensed pyrolizate (decay stage), and heat effects on window treatments (e.g., curtains, blinds) can provide important cues related to the stage of fire development and burning regime.

It is critical to take a holistic approach to observation of fire behavior indicators, to begin this process from the exterior, and to continue this process while operating on the interior.

Ed Hartin, MS, EFO, MIFIreE, CFO

Hazards Above

Thursday, July 8th, 2010

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

A Big Improvement, But More Work is Needed

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

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

Minneapolis, MN Residential Fire

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

Note: Photo by Steve Skar

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

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

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

Harrisonburg, VA Townhouse Fire

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


Note: Photo by Allen Litten

Sandwich MA Residential Fire

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

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

Questions

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

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

Late Breaking Information

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

References

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

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

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

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

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

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

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

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/

Battle Drill

Friday, February 5th, 2010

The Problem

NIOSH has investigated a number of incidents in which firefighters trapped by rapid fire progress did not take appropriate survival action. Last September, I was reading NIOSH Report F2007-02, which outlined the circumstances surrounding the death of Firefighter Steven Solomon in Atlanta, Georgia. Firefighter Solomon was severely burned after being caught by rapid fire development while advancing an attack line in a vacant structure (see Figure 1).

Figure 1. Rapid Fire Development

atlanta_lodd

Note: Atlanta Fire Department photo from NIOSH Report F2007-02

Firefighter Solomon was on the nozzle as the first arriving truck removed the plywood covering the front door and thick, black smoke came rolling out the top of the doorway. Firefighter Solomon and the crew of Engine 16 advanced the line into the building as the truck continued horizontal ventilation. After advancing a short distance, fire conditions quickly worsened and the crew attempted to back out, but collided with another company who was advancing a backup line. After exiting the building the crew of Engine 16 realized that Firefighter Solomon was still inside. Crews outside the door on Side A observed the silhouette of a firefighter running through the flames inside the building.

As I read the report, I asked myself how a firefighter on a hoseline that was just a short distance could have been killed by rapid fire development. The NIOSH report identified four contributing factors:

  • Initial size-up not conducted.
  • Failure to recognize the signs of an impending flashover/flameover.
  • Inadequate communication on the fireground.
  • Possibility of ventilation induced rapid fire progression.

While these factors likely contributed to Firefighter Solomon’s death, I still did not have a solid answer to my question of how a firefighter on a hoseline just a short distance inside the doorway could have died in this type of event.

Predictability

The best way to avoid being injured or killed in an extreme fire behavior event is to read the fire, anticipate likely fire behavior, and control your operating environment. A majority of our effort should be spent on mastering these skills.

There is no unpredictable fire behavior. Under the same conditions, a compartment fire will develop and behave consistently. However, conditions are not always the same! In addition, firefighters operate with limited information, imperfect skill in anticipating likely fire behavior, and often under pressure to take rapid action. When making decisions under pressure, in a complex and dynamic environment, and with limited information, potential for error increases.

Improved understanding of fire dynamics and development of a high level of skill reduces, but does not eliminate your risk of encountering extreme fire behavior. When this occurs it is essential that firefighters understand the fire behavior, their own reactions to stress, and have well practiced (to automaticity) responses to increase the chance of survival.

Training for Survival

What exactly are firefighter survival skills? Firefighters may encounter a number of life threatening problems while operating in the hazardous environment of as structure fire. Threats include breathing apparatus emergencies (e.g., malfunctions, running out of air), becoming disoriented, and being trapped by collapse or rapid fire progress.

A quick survey of survival skills training programs from around the United States shows a fair degree of consistency in curriculum content:

  • Emergency Communications Procedures (Mayday, Radio Emergency Distress Button)
  • Personal Alert Safety System (PASS) Activation
  • Reorientation, Searching for an Exit & Following a Hoseline to Safety
  • Air Conservation Techniques
  • Assuming a Horizontal Position to Enhance Thermal Protection and Audibility of the PASS
  • Escape to a Place of Refuge
  • Use of Visual and Audible Signals (Flashlight, Tapping with a Tool)
  • Reduced Profile Maneuvers to Escape Through Small Openings
  • Emergency Window Egress (Ladder Bail, Rope Systems)

These techniques may provide useful in dealing with a number of the threats that may be encountered in a structure fire. Taking refuge in an uninvolved compartment (with the door closed) may buy time for firefighters to escape through a window. However, the other elements will have little impact on increasing survival potential when encountering extreme fire behavior phenomena.

What is the missing element in the typical survival skills curriculum? In some cases, firefighters are taught breathing techniques to control their respiratory rate and conserve air, but little emphasis is provided on the psychological and physiological effects of the stress encountered in life threatening situations. This is critical to survival regardless of the nature of the threat. When faced with extreme fire behavior, particularly wind driven flames, flashover, and flash fire, appropriate nozzle technique and immediate tactical withdrawal to a safer area is absolutely critical. However, most survival skills curriculums do not address these critical skills.

When was the last time you practiced withdrawing a hoseline while operating the nozzle in the context of offensive, interior firefighting operations?

Performance Under Stress

There has been little if any research has been done to identify factors influencing firefighters’ performance under the extreme stress of a life threatening situation. However, there has been considerable investigation in other domains, particularly in the military and law enforcement

Increased psychological and physiological arousal prepare the human body for action. As this occurs, the sympathetic nervous system increases heart rate and blood pressure to maximize the body’s physical capacity. However, extreme levels of stress can result in significant deterioration in performance.

In On-Combat: The Psychology and Physiology of Deadly Conflict in War and Peace, LT COL Dave Grossman (2008) identifies five levels of arousal designated Conditions White, Yellow, Red, Grey, and Black. While cautioning against fixing specific heart rate numbers (or other precise physiological measures) to these levels of arousal, heart rate can be used as an indicator (see Figure 2).

Figure 2. Effects of Hormonal or Fear Induced Increases in Heart Rate

siddle_grossman_model

Note. Adapted from On-Combat: The Psychology and Physiology of Deadly Conflict in War and Peace (p. 31), by Dave Grossman, 2008, Millstadt, IL: Warrior Science Publications Copyright 2008 by David A. Grossman.

When face with an immediately life threatening situation, the resulting stress can significantly impact an individual’s ability to respond appropriately. In addition to the physiological responses (e.g. increased heart rate, visual and auditory distortion) decreased cognitive processing may delay appropriate response or result in freezing, with the inability to act (Wallenius, Johansson, & Larsson, 2002).

Recently a colleague related the experience of a firefighter who had been trapped by a wind driven fire. The firefighter dropped to the floor, went into the fetal position, said goodby to his wife and children and thought he was dead. Fortunately, the firefighter was rescued, but this illustrates the potentially incapacitating effects of stress in life threatening situations.

What is the answer? Military research points to the need for a highly trained (to automaticity) response. Battle drills integrate these immediate individual actions in the context of small unit operations.

Battle Drill

In a military context, battle drills are an immediate response to enemy contact that requires fire and maneuver in order to succeed. Battle drills are initiated with minimal commands from the unit leader. Soldiers or marines execute preplanned, sequential actions in response to enemy contact.

The battle drill concept has direct applicability to training firefighters to react appropriately on contact with our enemy (the fire) which requires fire (application of water) and maneuver (movement to a safer location) in order to succeed.

Unless a barrier (such as a door) is available to block the flow of flames and hot gases towards the firefighters position, attempts to escape without protection from a hoseline are likely to fail as fire can spread far more quickly than you can move.

Remember: The key elements of a battle drill are fire and maneuver! This requires the ability to operate and maintain control of the hoseline while moving backward.

The next post in this series will return to hose and nozzle drills with development of a battle drill for response to rapid fire progression.

Ed Hartin, MS, EFO, MIFireE, CFO.

References

Grossman, D. (2008). On-combat: The psychology and physiology of deadly conflict in war and peace. Millstadt, IL: Warrior Science Publications.

Wallenius, C. Johansson, C. & Larsson, G. (2002). Reactions and performance of Swedish peacekeepers in life-threatening situations. International Peacekeeping, 9(1), 133-152.

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