Posts Tagged ‘deliberate practice’

The previous post in this series, My Nozzle, examined the importance of nozzle knowledge and skill in using the firefighter’s primary weapon in offensive firefighting operations.

Figure 1. Practice is Essential to Effective Nozzle Technique

Note: These Fire Officers from Rijeka, Croatia are practicing the short pulse to place water fog into the hot gas layer. Droplet size, cone angle, position of the nozzle, and duration of application have placed water in the right form exactly where it was intended.

This is my nozzle, there are many like it but this one is mine. My nozzle is my best friend. It is my life. I must master it as I master my life. Without me it is useless, without my nozzle I am useless.

I will use my nozzle effectively and efficiently to put water where it is needed. I will learn its weaknesses, its strengths, its parts, and its care. I will guard it against damage, keep it clean and ready. This I swear [adapted from the Riflemans Creed, United States Marine Corps].

This post continues with a discussion of training methods and techniques that can be used to develop proficiency in nozzle techniques and hose handling.

Limitations in Fire Service Instructional Methods

Fire service instructor training and related instructional methods have direct linkage to the philosophy of vocational education that evolved in the United States in the early 1900s (Hartin, 2004). The philosophy of vocational education that evolved in the first half of the 20^th century put forth a mechanistic view of training and vocational education in which the goal is efficient production of trained individuals (Allen, 1919; Prosser & Allen, 1925). In early fire service instructor training, basic concepts of vocational education were combined with behaviorist psychological concepts of positive and negative reinforcement to guide learning. Over the last four decades, fire service instructor training has evolved to include humanist perspectives on motivation and the characteristics of adult learners. However, the basic principles used in training factory workers to perform simple repetitive tasks remain the meat and potatoes of this theoretical stew. All very interesting, but what does this have to do with nozzle technique?

The dominant focus of most fire service instructor training programs is on classroom instruction and to a lesser extent on demonstration of basic skills as an instructional method. Less focus is placed on effective methods for skills instruction (other than demonstration) and more importantly how to coach and provide effective feedback during skills instruction. Effectively and efficiently developing firefighters’ psychomotor skills requires a somewhat different focus.

There is a commonality between firefighters and athletes. Both require development of a wide range of physical and mental skills as well as underlying knowledge. A tremendous amount of research has been conducted on effective approaches to development of skill and proficiency in sport. Kinesiology (the science of human movement) and sport psychology provide a useful starting point for improving fire service skills training. While this post is focused on nozzle techniques and hose handling, the underlying theories can be applied to many other skills. It is essential that both the coach and the learner not only understand what needs to be done and how to do it, but why!

Motor Learning and Performance

A motor skill can be conceptualized as a physical task such as operating a nozzle or stretching a charged hoseline through a building. However, there are a number of dimensions on which these types of task can be classified:

• Task organization (simple, single task or multiple, interconnected tasks)
• Importance of motor and cognitive elements (doing or thinking)
• Environmental predictability (consistent or variable conditions)

Simply opening and closing the nozzle is a discrete task that predominantly involves motor skill, and takes place in a fairly predictable environment (the firefighters’ position may change, but the nozzle remains the same). However, when placed in the context of hoseline deployment inside a structure with variable fire conditions things change quite a bit. This involves serial (multiple, sequential) tasks and requires both physical and cognitive (decision-making) skills, in a somewhat predictable, but highly variable environment. This explanation makes things seem a bit more complicated than they appear at first glance!

Motor learning can be divided into several relatively distinct stages (Schmidt & Wrisberg, 2008). In the verbal-cognitive stage, learners are dealing with an unfamiliar task and spend time talking and thinking their way through what they are trying to do. As learners progress to the motor stage, they have a general idea of the movement required and shift focus to refining their skill. Progression through the motor stage often requires considerable time and practice. Some learners progress to the autonomous stage in which action is produced almost automatically with little or no attention. Other than the newest recruits, most firefighters are in the motor stage of learning when developing skill in nozzle techniques and hose handling.

Developing an understanding of motor performance and learning requires a conceptual model. However, in that many of you are likely to be less excited about learning theory than I am, I will make an effort to limit this to a simple framework.

1. Stimulus Identification: Recognize the need for physical action
2. Response Selection: Determination of the action needed.
3. Response Programming: Preparation and initiation of the required action.
4. Feedback: Determination of the effectiveness of the action (this loops back to stimulus identification and the process begins again).

In some cases, feedback is obtained during the action and corrective action can be taken during task performance (closed loop control). In other (shorter duration) tasks, feedback is received after the task is completed (open loop control)

Many nozzle techniques such as application of a short pulse of water fog into the hot gas layer involve open loop control as the action is completed before the firefighter can receive and process feedback on the effectiveness of the action. Training must develop sufficient skill (and preferably automaticity) to allow firefighters to apply various nozzle techniques with minimal conscious thought to allow focus on maintaining orientation in the building and key fire behavior indicators.

While there is much more to the story, this limited explanation of motor learning and performance provides a starting point to understand why the nozzle technique and hose handling drills are important and why they are designed the way that they are.

Nozzle Technique and Hose Handling Drills

One more bit of learning theory before we get our hands on the nozzle. This sequence of drills is designed using the Simplifying Conditions Method (Reigeluth, 1999). This approach moves from simple to complex, beginning with the simplest version of the task that represents the whole and moves to progressively more complex versions until the desired level of complexity is reached. In the case of nozzle technique and hose handling, this involves moving from basic, individual skills, to team skills, and on to integration of physical skills and decision-making.

Once basic proficiency is developed in simple tasks (such as the short pulse, long pulse, penciling, and painting), practice should be randomly sequenced (rather than blocked into practice of a single skill). In addition, practice should be distributed over a number of shorter sessions, rather than massed into fewer, but longer sessions. For more information on design of effective and efficient practice sessions, see Motor Learning and Performance (Schmidt & Wrisberg, 2008).

Drill 1-Basic Skills in Nozzle Operation: The starting point in developing a high level of proficiency in nozzle use is to gain familiarity with the nozzle(s) you will be using including performance characteristics such as flow rate, operating pressure, and nozzle controls (i.e., shutoff, pattern, flow). In addition, firefighters should build skill in basic nozzle techniques such as the short pulse, long pulse, penciling, and painting while in a fixed position. Click on the following link to download the instructional plan for Drill 1 in PDF format.

Hose and Nozzle Technique Drill 1 Instructional Plan

Firefighting is team based. After firefighters have demonstrated individual proficiency in basic nozzle techniques from a fixed position, the next step is to apply these techniques in a team context.

Drill 2-Hose Handling and Nozzle Operation: Firefighters often lose focus on nozzle technique and operation when they are moving. This drill provides an opportunity for the firefighter with the nozzle and backup firefighter to develop a coordinated approach to movement and operation.

Drill 3-Nozzle Operation Inside Compartments: Deployment of hoselines inside a building requires a somewhat different set of skills than simply moving forward and backward. Movement of hoselines around corners and adjustment of nozzle pattern to cool gases in hallways and varied size compartments are important additions to the firefighters’ skill set and provide the next step in developing proficiency in nozzle use.

Drills 2 and 3 will be addressed in the next post in this series. Subsequent posts will address door entry procedures, indirect attack, and will introduce the concept of battle drills to build skill in dealing with worsening conditions or other emergencies while operating inside burning buildings.

Ed Hartin, MS, EFO, MIFIreE, CFO

References

Hartin, E. (2004). Theoretical foundations of fire service instructor training (unpublished manuscript available from the author). Portland State University.

Allen, C. R. (1919). The instructor the man and the job. Philadelphia, PA: J. B. Lippencott Company. Prosser, C. A., & Allen, C. R. (1925). Vocational education in a democracy. New York: The Century Company.

Schmidt, R. & Wrisberg, C. (2008). Motor learning and performance (4^th ed.). Champaign, IL: Human Kinetics.

Reigeluth, C. (1999). Elaboration theory: Guidance for scope and sequence decisions. In C.M. Reigeluth (Ed.) Instructional-design theories and models: A new paradigm of instructional theory volume II. Mawah, NH: Lawrence Erlbaum Associates.

Warfare is often used as a metaphor for firefighting with fire being the enemy and the building the ground on which we fight. Extending warfare as a metaphor, handline nozzles are firefighters’ principle weapon in offensive firefighting operations.

In the early 1940s Major General William H. Rupertus, United States Marine Corps (USMC), wrote the Rifleman’s Creed (also known as My Rifle). The creed is part of Marine doctrine that emphasizes that regardless of specialty or assignment, all Marines are riflemen. The Rifleman’s creed emphasizes the criticality of caring for and mastering the use of the Marine’s individual weapon. How many firefighters have the same commitment to care and mastery of their nozzle?

All too often, firefighters consider the nozzle to be a simple device requiring little practice to master and seldom thought of until needed. Take a minute and think about the nozzle(s) that you use!

Nozzle Knowledge

These 20 questions focus on some of the fundamental knowledge that firefighters must have if they are truly going to master their primary weapon in offensive firefighting operations.

1. What kind of nozzle(s) are on your preconnected hoseline (combination or solid stream)?
2. What type of nozzles are they (i.e., fixed flow, variable flow, automatic, or single tip, stacked tips)?
3. What flow rate, rates, or range do they have?
4. If flow rate can be varied, how is this accomplished? Does the mechanism used to change flow operate freely?
5. If you change the flow without a corresponding change in line pressure at the pump, what happens to the nozzle pressure?
6. What is their designed operating pressure or pressures (for dual pressure nozzles)?
7. For combination nozzles, what is the impact of nozzle pressure on droplet size? Can you operate the nozzle at more than one nozzle pressure?
8. If a variable flow or automatic combination nozzle, does droplet size change with flow rate? Why might this be significant?
9. What is the maximum effective reach of the nozzle?
10. Can you flush debris from the nozzle? If so, how?
11. What type of coupling is the nozzle equipped with (e.g., if threaded, is it National Standard Hose, Iron Pipe, or some other thread)?
12. What type of valve is the nozzle equipped with (ball or slide valve) and what difference does it make?
13. If it is a combination nozzle, does it have fixed or spinning teeth? Why would this matter?
14. If the nozzle is equipped with spinning teeth, does the turbine spin freely?
15. Do your nozzles open and close easily when under pressure?
16. Are your nozzles clean (inside and out)? How should they be cleaned?
17. Do your nozzles require lubrication to ensure free movement of their operating mechanism? If so, when was the last time that they were lubricated?
18. If a combination nozzle, how to you adjust the nozzle to a wide angle fog pattern?
19. For combination nozzles, what is the maximum angle of the wide fog pattern?
20. If a combination nozzle, how far from straight stream or wide angle fog does the pattern control need to be turned to produced a 40^o (medium) fog pattern?

While knowing the answers to these questions, is necessary, it alone is not sufficient. In addition to knowledge of operating characteristics and maintenance procedures, firefighters must be skilled in nozzle operation in order to be able to accurately put water where it is needed.

Nozzle Skills

In some respects a nozzle is a fairly simple device designed to increase the velocity of water and provide a useful stream for firefighting operations. However, can you consistently:

1. Adjust a fog pattern to the desired angle without visual reference, before opening the nozzle to check the pattern?
2. Apply a short or long pulse of water fog so that the droplets evaporate in the hot gas layer, minimizing water contact with compartment linings (i.e. walls and ceiling)?
3. Apply a fog pattern to fill the maximum volume of a compartment without excessive water hitting the compartment linings?
4. Apply water gently in the form of a straight stream so that it flows onto a hot surface, maximizing cooling and minimizing runoff?
5. Recognize audible indicators of fire stream impact on compartment linings?
6. Adjust flow rate based on conditions and tactical application (i.e. gas cooling, indirect attack, direct attack)?
7. Maximize both effectiveness (in controlling the fire) and efficiency (by minimizing water use)?

These questions are obviously focused on combination nozzles. If you more commonly use solid stream nozzles, ability to cool hot gases is limited by the form in which water is applied. While limited in gas cooling effectiveness, what techniques can you use to have some impact on the threat presented by the hot gas layer?

As with knowledge of your nozzle, these skills are necessary, but not sufficient. Firefighters must be able to integrate physical skill with situational awareness and team based tactical skill.

My Nozzle

With due credit to General Rupertus and the USMC; I have adapted The Rifleman’s Creed:

This is my nozzle, there are many like it but this one is mine. My nozzle is my best friend. It is my life. I must master it as I master my life. Without me it is useless, without my nozzle I am useless.

I will use my nozzle effectively and efficiently to put water where it is needed. I will learn its weaknesses, its strengths, its parts, and its care. I will guard it against damage, keep it clean and ready. This I swear.

Developing Skill

During structural firefighting operations firefighters are faced with dynamic and rapidly changing conditions in which situational awareness is critical. Basic skills in the use of personal protective equipment and the tools of the firefighters’ craft must have reached the autonomous stage of performance to allow focus on critical decisions and tasks.

Habit hardens the body for great exertions, strengthens the heart in great peril, and fortifies the judgment against first impressions. Habit breeds that priceless quality, calm, which passing from hussar and rifleman up to the general himself, will lighten the commanders task. (Von Clausewitz, p. 122)

Colonel B.P. McCoy, USMC (2007) drew on Clausewitz’s wisdom in identifying combat marksmanship as a critical habit. “Anybody, even in the middle of a phobic response to the violence of combat can yank on a trigger and spray rounds in the general direction of the enemy, ‘spray and pray'” (p. 25). How many firefighters have the same response in the fire environment? “Combat marksmanship is the hallmark of the infantryman. Nothing nurtures confidence like the knowledge that one can hit what one is shooting at” (McCoy, 2007, p. 25). Firefighters require the same skill in nozzle use as Colonel McCoy’s Marines required in the use of their rifles.

During offensive firefighting operations firefighters apply water for one of two purposes. 1) to cool hot gases or 2) to cool hot surfaces (Grimwood, Hartin, McDonough, & Raffel, 2005). Each of these tasks requires a different method to put water where it is needed in a form that will accomplish the intended outcome.

Gas Cooling: In general water application to cool hot gases should be based on the following requirements:

• Most of the water applied must vaporize in the hot gas layer (not on surfaces)
• Nozzle pattern should maximize the volume of hot gases cooled.

The challenge to the nozzle operator is that there is not one single approach to meeting these requirements. In general, smaller droplets work better than large droplets, but nozzle pattern (wide, medium, or narrow fog) is dependent on the size of the space and temperature of the flames and/or hot, unignited gases.

Surface Cooling: The requirement for cooling hot surfaces is different than those required for gas cooling, but is equally simple.

Most of the water applied must vaporize on contact with hot surfaces (not in the hot gas layer)

As with gas cooling there is not a single approach to meeting these requirements. In general, effective surface cooling requires a thin layer of water on the hot surface. If the surface is extremely hot, water application must be continued until the temperature is reduced sufficiently to slow and stop pyrolysis.

Important! Water on the floor after extinguishment is completed did not do significant work. Far more energy is required for water to change phase into steam than to simply raise its temperature. Water application must be effective (in achieving fire control), but should also be efficient (in minimizing the water used and limiting fire control damage).

Effective and efficient fire control requires that firefighters be skilled at putting water in the right form where it is needed (in the hot gases or on hot surfaces). Development of autonomous (habitual) skill in nozzle use requires deliberate practice. This is not simply repetition of our current skills, but continuing to stretch just beyond our current abilities. Deliberate practice is designed specifically to improve sharply defined elements of performance.

The next several posts in this series will examine how research in sport psychology regarding motor learning and performance can be used to enhance our ability to develop proficiency in nozzle use (as well as other physical firefighting skills).

Ed Hartin, MS, EFO, MIFireE, CFO

References

US Army (1992). Field manual 7-8 infantry Rifle platoon and squad. Washington, DC: Headquarters, Dept. of the Army.

Clausewitz, C. (1984) On war. (M. Howard & P. Paret, Trans.). Princeton, NJ: Princeton University Press

McCoy, B. (2007). The passion of command. Quantico, VA: The Marine Corps Association.

Grimwood, P., Hartin, E., McDonough, J, & Raffel, S. (2005) 3D firefighting: Training, techniques, and tactics. Stillwater, OK: Fire Protection Publications.

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

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 500^o-600^o C (932^o-1112^o 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

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 700^o-1200^o C (1292^o-2192^o 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

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.

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 home’s 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 .

Chicago Dollar Store Fire

On the morning of October 1, 2009 the Chicago Fire Department (CFD) responded to a fire in the Super Dollar and Up store at 3952 West Cermak Road. CFD Senior Fire Alarm Operator and Fire Photographer Steve Redick captured early incident operations on video.

The first segment of the video was shot in the alley on Side C from the B/C Corner. The next several minutes of video are shot from positions on Side A as indicated in Figure 1.

Figure 1. Plot Plan and Approximate Video Camera Locations

Download the B-SAHF Worksheet.

Watch the first 60 seconds of Video Segment 1. Consider the information provided in this segment of the video clip. First, describe what you observe in terms of the Building, Smoke, Air Track, Heat, and Flame Indicators and then answer the following five standard questions?

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

After completing the B-SAHF worksheet and answering the five standard questions, watch the next minute and twenty seconds of the video.

1. Did you anticipate this change?
2. What factors may have influenced this change in conditions?

Visit Steve Redick’s Web Site for additional video and excellent photos of this incident.

Memphis Dollar Store LODD

The rapidly changing conditions in the Chicago incident reminded me of the fire in Memphis, Tennessee that took the lives of Lieutenant Trent Kirk and Private Charles Zachary. Similar to the fire in Chicago, this incident involved a fire in a one-story, non-combustible building containing multiple commercial occupancies. As companies arrived they observed a small volume of smoke from the roof and little smoke inside the building. Approximately nine minutes after arrival conditions worsened with a large volume of smoke pushing from the doorway on Side A. Crews became disoriented as a result of rapid fire progression, and Lieutenant Kirk and Private Zachary were trapped.

For additional information on this incident see NIOSH Death in the Line of Duty Report F2003-18 and Memphis Fire Department Director’s Review Board Family Dollar Store Fire report.

Dollar Stores as a Target Hazard

Dollar stores and similar types of commercial occupancies should be considered as a target hazard that presents a significant threat to firefighters. These types of stores are generally in an enclosed building (good access from the front, but not generally from the other sides of the building) with high ceilings and a cockloft or other ceiling void space. In addition, this type of store contains a large fuel load comprised predominantly of synthetic fuel with a high heat of combustion (think high energy) and potential for extremely rapid fire development.

Fires in this type of occupancy are not uncommon! A quick search uncovered 15 similar incidents across the United States in the last three years (and 11 in 2009). There were likely more (as the scope of this search looked for fires in “dollar stores” and stopped after the first several hundred hits with the Google search engine).

• Broadview, IL (June 9, 2009)
• Flint, MI (August 24, 2009)
• Lubbock, TX (September 15, 2009)
• Terre Haute, IN (June 29, 2009)
• New York, NY (June 9, 2009)
• Midlothian, IL (February 6, 2008)
• Highland Park, MI (October 7, 2007)
• Denver, CO (June 29, 2009)
• Sanford, FL (March 23, 2009)
• Chattanooga, TN (April 14, 2009)
• Conklin, NY (August 27, 2009)
• Muncie, IN (September 16, 2009)
• Lake Worth, TX (November 25, 2006)
• Omaha, NE (April 8, 2008)
• Bells Corner, PA (June 3, 2009)

Building Factors and Fire Behavior

Building factors include the construction, configuration, and contents of a structure. These factors are critical fire behavior indicators that must be assessed during pre-planning and in the course of size-up and incident operations. Consider how building size (particularly volume, ceiling height, and presence of ceiling, attic, or cockloft void spaces) impacts on both fire behavior and how the other B-SAHF indicators present.

Reporting on the Dollar Store fire in Chattanooga, TN in April 2009, a Chattanooga Fire Department spokesperson said:

At first, it appeared that the firefighters would be able to get the fire under control fairly quickly, but the fire got into the attic and was difficult to locate in the thick, black smoke… The firefighters made an interior attack and tried to use thermal imaging cameras to locate the fire. However, other firefighters noticed that the roof was beginning to sag, so the order was given to evacuate the building for the safety of the firefighters.

It is essential to recognize potential for worsening conditions and extreme fire behavior. This is particularly important when faced with an incident outside the norm of fires in residential structures such as one and two-family dwellings and apartments.

Posts from Sandö, Sweden

Next week I will be posting from Sandö, Sweden as 12-16 October I will be participating in a Compartment Fire Behavior Training Workshop at the Swedish Civil Contingencies Agency College. Along with representitives from Australia, Canada, Germany, and Spain, I will be studying contemporary approaches to fire behavior training as well as the evolution of Swedish fire behavior training since the 1980s. This workshop provides a tremendous opportunity to learn along with Mats Rosander, Nils Bergström, and Marcos Dominguez, poneers in the evolution of fire behavior training in Sweden and around the world.

Ed Hartin, MS, EFO, MIFIreE, CFO

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:

• Fire Behavior Case Study Townhouse Fire: Washington, DC
• Townhouse Fire: Washington DC-What Happened
• Townhouse Fire: Washington DC-Extreme Fire Behavior
• Townhouse Fire: Washington DC-Computer Modeling

Figure 1. Conditions at Approximately 00:28

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

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

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

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

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

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

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

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

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

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

Figure 12. Thermal Exposure Limits in the Firefighting 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 37^o C (98.6^o 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 38^o C (100^o 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 260^o C (500^o 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 1000^o C (1832^o 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

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 (68°F 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

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

The last post in this series, Incipient Fires: Key Fire Behavior Indicators reviewed stages of fire development (i.e., incipient, growth, fully developed, and decay), burning regimes (i.e., fuel and ventilation controlled) and identified key indicators used to recognize incipient stage fires. This post examines key indicators to identify growth stage fires and their burning regime.

Growth Stage & Burning Regime

Like many concepts in fire dynamics there is a bit of ambiguity between where the incipient stage ends and the growth stage begins. For firefighters, this distinction is important as growth stage fires are deemed to present an Immediately Dangerous to Life and Health (IDLH) threat based on the increasing speed of fire development, toxicity and thermal environment. This triggers Occupational Safety and Health Administration (OSHA) respiratory protection regulations requirements for “two-in/two-out”. Key characteristics of a growth stage fire include increasing heat release rate (HRR), significantly increasing temperature within the compartment.

The speed of fire development in the growth stage may be limited by fuel characteristics and configuration or ventilation. Typically compartment fires in the early growth stage are fuel controlled. However, if the compartment is small and/or has limited ventilation, continued combustion will result in slowing fire development as the fire enters the ventilation controlled burning regime. Recognizing the ventilation controlled burning regime is critical as increases in ventilation will result in increased HRR. This is not necessarily a major problem unless it is unanticipated or firefighters do not have the capacity to control this additional HRR.

A Single Compartment

While most buildings have multiple, interconnected rooms, providing a complex environment for fire development, it is useful to begin by examining fire development in a single compartment (see Figure 1)

Figure 1. Fire Development in a Single Compartment.

Note: Photos adapted from National Institute of Standards and Technology (NIST) ISO-Room/Living Room Flashover [Digital Video Disk].

As a compartment fire develops hot products of combustion and entrained air rise in a plume from the burning fuel package. When the plume reaches the ceiling, hot gases begin to move horizontally, forming a ceiling jet. As the fire progresses through the incipient stage and into growth, additional fuel will become involved and the heat release rate from the fire will increase. While thermal conditions can be considerably more complex, gas temperatures within the compartment may be described as existing in two layers: A hot layer extending down from the ceiling and a cooler layer down towards the floor. Convection resulting from plume and ceiling jet along with radiant heat from the fire and hot particulates in the smoke increases the temperature of the compartment linings and other items in the compartment.

The fire can continue to grow through flame spread or by ignition of other fuel within the compartment. As flames in the plume reach the ceiling they will bend and begin to extend horizontally. Pyrolysis products and flammable byproducts of incomplete combustion in the hot gas layer will ignite and continue this horizontal extension across the ceiling. As the fire moves further into the growth stage, the dominant heat transfer mechanism within the fire compartment shifts from convection to radiation. Radiant heat transfer increases heat flux (transfer of thermal energy) at floor level.

As gases within the compartment are heated they expand and when confined by the compartment increase in pressure. Higher pressure in this layer causes it to push down within the compartment and out through openings. The pressure of the cool gas layer is lower, resulting in inward movement of air from outside the compartment. At the point where these two layers meet, as the hot gases exit through an opening, the pressure is neutral. The interface of the hot and cool gas layers at an opening is commonly referred to as the neutral plane.

If the compartment is sealed (e.g., door closed and windows intact), the fire may become ventilation controlled, slowing the increase in HRR and temperature, and eventually moving the fire into the decay stage (defined by decreasing HRR). However, if the compartment is not sealed (e.g., open door), the fire may become ventilation controlled, but HRR can continue to increase as smoke flows out of the involved compartment and air from the remainder of the building flows in at floor level, providing the oxygen necessary for continued combustion.

In growth stage fires, fire behavior indicators are often visible from the exterior of the building. However, depending on fire location and building factors (e.g., energy efficiency, ventilation profile) these indicators may be fairly obvious or quite subtle. Growth stage indicators are listed in Figure 2

Figure 2. FBI: Growth Stage

In Incipient Fires: Key Fire Behavior Indicators you were presented with a residential fire scenario as an opportunity to give some thought to how key fire behavior indicators may present. Consider

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 growth stage fire is burning a bedroom on the Alpha Bravo corner of the structure. The fire involves a plastic trash can, the bed, and night stand.

• What conditions would you expect to see from the exterior of the structure?
• What indicators may be visible from the front door as you make entry?
• What indicators would you anticipate observing as you traveled through the living room and down the hallway to the bedroom where the fire is located?
• What conditions would you find in the bedroom?

As the fire moves through the growth stage, the speed at which conditions change increases rapidly. 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?

More to Follow

The next post in this series will continue examination of the relationship between the B-SAHF indicators, fire development, and burning regime by connecting to the parallel series of posts on flashover and examining fully developed fires.

Ed Hartin, MS, EFO, MIFireE, CFO

References

National Institute of Standards and Technology. (2005). ISO-room/living room flashover [digital video disk]. Gaithersburg, MD: Author.

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

A Quick Review

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

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

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

Modeling of the Cherry Road Incident

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

Fire Modeling

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

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

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

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

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

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

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

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

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

Figure 1. Cross Section of 3146 Cherry Road NE

Figure 2. Side A 3146 Cherry Road NE

Figure 3. Side C 3146 Cherry Road NE

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

Figure 4. FDS Heat Release Rate Curve

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

Questions

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

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

More to Follow

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

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

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

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

Compartment Fire Development

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

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

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

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

Hazard of Ventilation Controlled Fires

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

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

Figure 2. Ventilation Induced Flashover

Incipient Stage

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

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

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

Application Exercise

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

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

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

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

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

More to Follow

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

Ed Hartin, MS, EFO, MIFireE, CFO

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

A Quick Review

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

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

Extreme Fire Behavior

Proceeding from their entry point on Side C towards the stairway to Floor 1 on Side A, Rescue 1B and the firefighter from Truck 4 observed fire burning in the middle of the basement room. Nearing the stairs, temperature increased significantly and they observed fire gases in the upper layer igniting. Rescue 1B and the firefighter from Truck 4 escaped through the basement doorway on Side C as the basement rapidly transitioned to a fully developed fire.

Figure 1. Timeline Leading Up to the Extreme Fire Behavior Event

The timeline illustrated in Figure 1 is abbreviated and focuses on a limited number of factors. A detailed timeline, inclusive of tactical operations, fire behavior indicators, and fire behavior is provided in a subsequent section of the case.

After Engine 17’s line was charged, the Engine 17 officer asked Command for permission to initiate fire attack from Side C. Command denied this request due to lack of contact with Engines 26 and 10 and concern regarding opposing hoselines. Due to their path of travel around Side B of the building, Engine 17 had not had a clear view of Side A and thought that they were at a doorway leading to Floor 1 (rather than the Basement). At this point, neither the companies on Side C nor Command recognized that the building had three levels on Side C and two levels on Side A.

At this point crews from Engine 26 and 10 are operating on Floor 1 and conditions begin to deteriorate. Firefighter Morgan (Engine 26) observed flames at the basement door in the living room (see Figure 8 which illustrates fire conditions in the basement as seen from Side C). Firefighter Phillips (Engine 10) knocked down visible flames at the doorway, but conditions continued to deteriorate. Temperature increased rapidly while visibility dropped to zero.

As conditions deteriorated, Engine 26’s officer feels his face burning and quickly exits (without notifying his crew). In his rapid exit through the hallway on Floor 1, he knocked the officer from Engine 10 over. Confused about what was happening Engine 10’s officer exited the building as well (also without notifying his crew). Engine 26’s officer reports to Command that Firefighter Mathews was missing, but did not report that Firefighter Morgan was also missing. Appearing dazed, Engine 10’s officer did not report that Firefighter Phillips was missing.

Figure 2. Conditions on Side C at Aproximately 00:28

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

Figure 3. Conditions on Side A at Aproximately 00:28

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

Firefighter Rescue Operations

After the exit of the officers from Engine 26 and Engine 10, the three firefighters (Mathews, Phillips, and Morgan) remained on Floor 1. However, neither Command (Battalion 1) nor a majority of the other personnel operating at the incident recognized that the firefighters from Engines 26 and 10 had been trapped by the rapid extension of fire from the Basement to Floor 1 (see Figure 4).

While at their apparatus getting a ladder to access the roof from Side B, Truck 4B observed the rapid fire development in the basement and pulled a 350′ 1-1/2″ (107 m 38 mm) line from Engine 12 to Side C, backing up Engine 17.

Figure 4. Location of Firefighters on Floor 1

Note: Adapted from Report from the Reconstruction Committee: Fire at 3146 Cherry Road NE, Washington DC, May 30, 1999, p. 18 & 20. District of Columbia Fire & EMS, 2000 and Simulation of the Dynamics of the Fire at 3146 Cherry Road NE, Washington D.C., May 30, 1999, p. 12-13, by Daniel Madrzykowski & Robert Vettori, 2000. Gaithersburg, MD: National Institute of Standards and Technology.

Engine 17 again contacted Command (Battalion 1) and requested permission to initiate an exterior attack from Side C. However, the officer of Engine 17 mistakenly advised Command that there was no basement entrance and that his crew was in position to attack the fire on Floor 1. Unable to contact Engines 10 and 26, Command denied this request due to concern for opposing hoselines. With conditions worsening, Command (Battalion 1) requested a Task Force Alarm at 00:29, adding another two engine companies, truck company, and battalion chief to the incident.

Firefighter Phillips (E-10) attempted to retreat from his untenable position at the open basement door. He was only able to travel a short distance before he collapsed. Firefighter Morgan (E-26) heard a loud scream to his left and then a thud as if someone had fallen to the floor (possibly Firefighter Mathews (E-26)). Firefighter Morgan found the attack line and opened the nozzle on a straight stream, penciling the ceiling twice before following the hoseline out of the building (to Side A). Firefighter Morgan exited the building at approximately 00:30.

Rescue 1B entered the structure on Floor 1, Side A to perform a primary search. They crawled down the hallway on Floor 1 towards Side C until they reached the living room and attempted to close the open basement door but were unable to do so. Rescue 1 B did not see or hear Firefighters Mathews (E-26) and Phillips (E-10) while working on Floor 1. Rescue 1B noted that the floor in the living room was spongy. The Rescue 1 Officer ordered his B Team to exit, but instead they returned to the front door and then attempted to search Floor 2, but were unable to because of extremely high temperature.

Unaware that Firefighter Phillips (E-10) was missing, Command tasked Engine 10  and Rescue 1A, with conducting a search for Firefighter Mathews (E-26). The Engine 10 officer entered Floor 1 to conduct the search (alone) while instructing another of his firefighters to remain at the door. Rescue 1A followed Engine 26’s 1-1/2″ (38 mm) hoseline to Floor 1 Slide C. Rescue 1B relocated to Side B to search the basement for the missing firefighter.

The Engine 26 Officer again advised Command (Battalion 1) that Firefighter Mathews was missing. Engine 17 made a final request to attack the fire from Side C. Given that a firefighter was missing and believing that the fire had extended to Floor 1, Command instructed Engine 17 to attack the fire with a straight stream (to avoid pushing the fire onto crews working on Floor 1). At approximately 00:33, Battalion 2 reported (from Side C) that the fire was darkening down. Engine 14 arrived and staged on Bladensburg Road.

Command ordered a second alarm assignment at 00:34 hours. At 00:36, Command ordered Battalion 2 (on Side C) to have Engine 17 and Truck 4 search for Firefighter Mathews in the Basement. Engine 10’s officer heard a shrill sound from a personal alert safety system (PASS) and quickly located Firefighter Phillips (E-10). Firefighter Phillips was unconscious, lying on the floor (see Figure 4) with his facepiece and hood removed. Unable to remove Firefighter Phillips by himself, the officer from Engine 10 unsuccessfully attempted to contact Command (Battalion 1) and then returned to Side A to request assistance.

Command received a priority traffic message at 00:37, possibly attempting to report the location of a missing firefighter. However, the message was unreadable.

The Hazmat Unit and Engine 6 arrived and staged on Bladensburg Road and a short time later were tasked by Command to assist with rescue of the downed firefighter on Floor 1. Firefighter Phillips (E-10) was removed from the building by the Engine 10 officer, Rescue 1A, Engine 6, and the Hazardous Materials Unit at 00:45. After Firefighter Phillips was removed to Side A, Command discovered that Firefighter Mathews (E-26) was still missing and ordered the incident safety officer to conduct an accountability check. Safety attempted to conduct a personnel accountability report (PAR) by radio, but none of the companies acknowledged his transmission.

The Deputy Chief of the Firefighting Division arrived at 00:43 and assumed Command, establishing a fixed command post at the Engine 26 apparatus. Battalion 4 arrived a short time later and was assigned to assist with rescue operations along with Engines 4 and 14.

Firefighter Mathews was located simultaneously by several firefighters. He was unconscious leaning over a couch on Side C of the living room (see Figure 4). Firefighter Mathews breathing apparatus was operational, but he had not activated his (non-integrated) personal alert safety system (PASS). Firefighter Mathews was removed from the building by Engine 4, Engine 14, and Hazardous Materials Unit at 00:49.

Command (Deputy Chief) ordered Battalions 2 and 4 to conduct a face-to-face personnel accountability report on Sides A and C at 00:53.

Questions

1. Based on the information provided in the case to this point, answer the following questions:
2. National Institute for Occupational Safety and Health (NIOSH) Death in the Line of Duty Reports examining incidents involving extreme fire behavior often recommend close coordination of fire attack and ventilation.
3. Did the fire behavior in this incident match the prediction you made after reading the previous post (Towhouse Fire: Washington DC-What Happened)?
4. What type of extreme fire behavior occurred? Justify your answer?
5. What event or action initiated the extreme fire behavior? Why do you believe that this is the case?
6. How did building design and construction impact on fire behavior and tactical operations during this incident?
7. How might a building pre-plan and/or 360^o reconnaissance have impacted the outcome of this incident? Note that 360^o reconnaissance does not necessarily mean one individual walking completely around the building, but requires communication and knowledge of conditions on all sides of the structure (e.g., two stories on Side A and three stories on Side C).
8. How might the outcome of this incident have changed if Engine 17 had been in position and attacked the fire in the basement prior to Engines 26 and 10 committing to Floor 1?
9. What strategies and tactics might have been used to mitigate the risk of extreme fire behavior during this incident?

More to Follow

This incident was one of the first instances where the National Institute of Standards and Technology (NIST) Fire Dynamics Simulator (FDS) was used in forensic fire scene reconstruction (Madrzykowski & Vettori, 2000). Modeling of the fire behavior in this incident helps illustrate what was likely to have happened in this incident. The next post in this series will examine and expand on the information provided by modeling of this incident.

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

The first post in this series, Reading the Fire: How to Improve Your Skills, I discussed building a concept map of fire behavior indicators as a method to increase competence in reading the fire. In the 12 posts that followed, we have explored each of the categories of the B-SHAF organizing scheme by developing a concept map for each type of indicator.

• How to Improve Your Skills
• Building Factors
• Building Factors Part 2
• Building Factors Part 3
• Smoke Indicators
• Smoke Indicators Part 2
• Air Track Indicators
• Air Track Indicators Part 2
• Heat Indicators
• Heat Indicators Part 2
• Heat Indicators Part 3
• Flame Indicators
• Flame Indicators Part 2

I have been working through this process as well in an effort to expand and refine my personal B-SAHF concept map. This post will review the work accomplished so far and lay the foundation for moving to the next step in the process; applying B-SAHF to recognize key indicators and predict likely fire behavior.

This review will be graphic, using the current version (5.2.2.1) of each of the concept maps developed in this series of posts.

Building Factors

Unlike the other elements of the B-SAHF organizing scheme for fire behavior indicators, Building Factors are present before the fire. Frank Brannigan was fond of saying “the building is the enemy” (Brannigan & Corbett, 2008, p. 81). The term enemy (2009) can be used to describe one who is antagonistic or seeking to injure or harm another. In this sense the building is not our enemy as it has no intent. However, it may also be used to describe something that is potentially harmful (Enemy, 2009). From this perspective Frank could be correct. However, I find that in the use of warfare as a metaphor for firefighting, I find it more useful to consider the building as the terrain that we fight on, rather than the enemy.

Building factors (such as use of lightweight or engineered wood support systems) present a significant hazard, but only under fire conditions. Fire dynamics and building performance under fire conditions are interrelated and should be key considerations in the pre-planning process.

In many respects, Building Factors is the most complex category of the fire behavior indicators. Figure 1 illustrates my current concept map capturing many (but likely not all) of the key building factors that influence fire behavior.

Figure 1. Building Factors

Consider what other building factors might be of interest or concern as well as how these factors may be interrelated with the other elements of the B-SAHF scheme.

Smoke Indicators

There are a significant number of interrelationships between smoke indicators and the other elements of the B-SAHF model, particularly Building Factors, Air Track, and Heat. These relationships reinforce the importance of looking at fire behavior indicators holistically, rather than simply as individual elements.

Figure 2. Smoke Indicators

Are there other indicators related to smoke that may be useful in identifying or assessing the stage of fire development, burning regime, or other important aspects of fire behavior? What additional interrelationships exist with the other elements of B-SAHF?

Air Track Indicators

Air track is the movement of both smoke (generally out from the fire area) and air (generally in towards the fire area). Air track is caused by pressure differentials inside and outside the compartment and by gravity current (differences in density between the hot smoke and cooler air). Air track indicators include velocity, turbulence, direction, and movement of the hot gas layer. As in the case of smoke, air track is closely interrelated with Building Factors, Smoke, and Heat Indicators.

Figure 3. Air Track Indicators

Are there other air track indicators that might be useful in assessing conditions and making predictions about likely fire behavior? What other interrelationships exist between air track and the other elements of B-SAHF?

Heat Indicators

In considering heat indicators, it is important to distinguish between energy, temperature, and heat. While this category is titled heat indicators, much of what we observe and feel is based on increased temperature due to transfer of energy (energy in transit is heat). To review the discussion of energy, temperature and heat, see Reading the Fire: Heat Indicators.

Figure 4. Heat Indicators

What other heat indicators may be useful in assessing conditions, the risk to firefighters, and impact of tactical operations on fire behavior? Are there additional interrelationships with other elements of B-SAHF?

Flame Indicators

Flames are the visible, light emitting product of combustion. In compartment fires, flames are the result of glowing particulate material (predominantly carbon). While extremely useful, information from flame indicators must be considered in conjunction with the other elements of B-SAHF.

Figure 5. Flame Indicators

Are there other flame related indicators that might be useful? Are there additional interrelationships with other elements of B-SAHF?

Applying B-SAHF

Developing your skill in reading the fire requires ongoing deliberate practice. What does this look like? In the following video clip, Tiger Woods is described as “just a pro who wants his game to get better, every day”

Are we professionals who want our skill at reading the fire to get better, every day? What does will it take for us to accomplish this task? It takes more than just talking about it or attending a class. Developing this level of skill requires ongoing, deliberate practice. Building a concept map of the B-SAHF indicators is an early step in this process as it gives you a way to think about information provided by the building and fire that will allow you to recognize important conditions and what is likely to happen next. Developing this understanding is necessary, but not sufficient. You also need to work on your skill at recognition and developing the ability to interpret this information in the context of the situation.

Using video is a great way to practice your skill in recognizing key indicators. On the fireground, you may only see a particular indicator for a few seconds. There is no instant replay. However, with video you can watch a particular clip again and again to practice your skill and develop the ability to separate critical indicators from the noise of extraneous information.

Practice Your Craft!

Reading the fire and recognizing likely and potential fire development is a critical part of initial size-up and action planning. However, this process needs to continue throughout incident operations as you evaluate the impact of tactical operations (the responsibility of everyone on the fireground, not just officers or the incident commander). Use the following two video clips of tactical operations to practice your skill (and maybe discover a few additional indicators to add to your B-SAHF concept maps).

Video Clip1-Roof Operations: Watch this video clip of vertical ventilation operations and identify the key B-SAHF Indicators. What information do the building, smoke, air track, heat, and flame indicators provide about current conditions? How is fire behavior likely to change?

Video Clip 2-Fire Attack: Watch this video clip of initial attack operations at a commercial fire. What building, smoke, air track, heat, and flame indicators can you observe in this clip? What information do these indicators provide? How do the indicators change based on application of water? What can you determine based these changes?

More to Follow

The next post in this series will begin to examine application of the B-SAHF scheme to recognizing stages of fire development and burning regime as part of initial and ongoing size-up and situation assessment.

Ed Hartin, MS, EFO, MIFireE, CFO

References

Brannigan, F. & Corbett, G. (2008). Building construction for the fire service. Sudbury, MA: Jones & Bartlett.

Enemy. (2009). In Merriam-Webster Online Dictionary. Retrieved September 17, 2009, from http://www.merriam-webster.com/dictionary/enemy