Posts Tagged ‘FBI’

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

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.

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

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

The previous post in this series, Reading the Fire: Flame Indicators briefly looked at flames, the visible, light-emitting product of combustion and identified several basic categories of flame related fire behavior indicators as illustrated in Figure 1.

Figure 1. Basic Flame Indicators

As with each of the B-SAHF (building, smoke, air track, heat, and flame) indicators, it is essential that assessment of flame related indicators is integrated with other elements of the B-SAHF scheme to gain a clearer sense of fire conditions and likely fire behavior.

Size and Location

Location of the flames may provide important information. If flames are visible from outside the structure, where are they coming from? It is important to connect this information with building factors such as compartmentation. Is fire showing from a single window due to compartmentation or simply because that is the only window that has failed? Are the flames pushing from inside a compartment or is smoke igniting and burning outside?

Given the conditions depicted in Figure 2, the size and location of flames make it obvious that the fire involves multiple compartments of this single family dwelling. However, it is important not to be distracted or deceived by conditions observed from one location!

Figure 2. Fire Showing from a Single Family Dwelling

Note: Photo by Marc Caron, Gatineau, Québec Canada

Early on the morning of July 21, 2007; Contra Costa County Engine 70 responded to a residential fire with persons reported at 149 Michelle Drive. On arrival, Engine 70 observed fire showing from the door and large picture window on Side A. From this limited view of the building, the fire appeared to be in the living room with potential for trapped occupants in the bedrooms. Engine 70 went to work knocking down the fire from the doorway and initiating a primary search of the bedrooms. However, conditions were not as simple as they seemed. The fire, which had originated in one of the bedrooms on Side B was burning in a ventilation controlled state with a substantial accumulation of gas phase fuel in the bedrooms and hallway. As Engine 70 conducted their search, increased ventilation returned the fire to flaming combustion, igniting the gas phase fuel (smoke) in a flash fire that killed Captain Matthew Burton and Engineer Scott Desmond (for more information on this incident see: Contra Costa LODD, Contra Costa LODD: Part 2, Contra Costa LODD: What Happened?).

It is absolutely critical that observation of flames be integrated with all of the B-SAHF indicators from more than one perspective. The first arriving officer should conduct a 360^o reconnaissance whenever possible. However, this is not always possible. If the first arriving company cannot accomplish this task, it does not diminish the importance of determining conditions on other sides of the building and another company should be assigned to complete this task as soon as possible.

While working inside the building, what is the flame height? Are the flames impinging on the ceiling and bending to travel horizontally? Do you observe flames in the hot gas layer (i.e., ghosting, rollover)? Fire development speeds considerably after flames in the plume of hot gases reach the ceiling and begin to travel horizontally in the ceiling jet. Isolated flames in the hot gas layer are a strong indicator of a ventilation controlled fire. Flames in the hot gas layer or development of rollover are an important indicator of imminent flashover.

With flame indicators, it is not just what you see that is important. What you do not see is equally important. Remember that the low oxygen concentration in backdraft conditions may preclude flaming combustion (at least in that compartment). However, conditions can vary widely from compartment to compartment (void spaces are compartments too!) and you may have visible flames from the exterior, but quite different conditions inside the building.

As with other fire behavior indicators, change over time is an important indication of fire development or progress towards control. This is particularly true with flaming combustion. Once fire control operations have started, firefighters and fire officers must evaluate the effect of fire streams. Failure of water application to reduce the size of the fire indicates that either the flow rate is inadequate, the application point is ineffective, or both.

Flame Color

Flame color is largely dependent on the type of fuel involved and the extent to which the fuel and oxygen are mixed (see the previous post Reading the Fire: Flame Indicators, Figure 2-Diffusion and Premixed Flames). Because there are several influences on flame color, it is important to interpret this information in context with other fire behavior indicators. Organic materials (natural or synthetic) will tend to burn with light yellow to reddish orange color depending on oxygen concentration as illustrated in Figure 3.

Figure 3. Fire Showing

Note: Photo courtesy of Mercer County Fire Protection District

While flame color can often be observed from the exterior as illustrated in Figure 3, it is also important while working inside as observed by Captain James Mendoza of the San Jose Fire Department.

The coloration of diffusion flames commonly encountered in structure fires runs from red to orange to yellow to almost white. This scale tells you something about the energy of the fire, with the redder the flame, the less temperature and radiant heat it is releasing. Often the lower energy red flames are due to combustion occurring with limited air, and if ventilation is increased, the energy released increases, temperature increases, and color changes from red to orange to yellow to white. So, if you are feeling extreme heat as you move towards dark orange flames, realize the air you just let in by opening the door can make the conditions worse, and you may be able to see that visually by a lighter flame color.

If organic fuel gas or vapor is premixed with air, flame color will be bluish. In compartment fires, a lazy bluish flame moving through the hot gas layer is an indication of a substantially ventilation controlled fire. However, it is important to remember that flame contact with other materials may influence color. For example, flame impinging on copper will have a blue green color.

Less commonly encountered in compartment fires, a bright white flame is usually indicative of high temperature such as that generated by burning metal (i.e., magnesium).

Duration

Given adequate fuel and oxygen, flaming combustion is likely to be continuous. However, when a compartment fire is burning in a ventilation controlled regime, flames may be intermittent as fuel and oxygen concentration varies. Watch the following video and observe the difference in flaming combustion from the window on Side B in the first 45 seconds (0:00 to 0:45) and from the window on Side A the next 30 seconds (00:46 to 1:16). How are the flames different? Why do you think that this is the case?

Work in Progress

Hopefully we have been working on this project together and you have been developing or refining the flame segment of your fire behavior indicators concept map. My current map is illustrated in Figure 4.

Figure 4. Flame Indicators Concept Map v5.2.2.1

You can also download a printer friendly version of the Flame Indicators Concept Map v5.2.2.1 As always, should you have any suggestions or feedback, please post a comment!

Ed Hartin, MS, EFO, MIFireE, CFO

In 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. Construction of a concept map increases awareness of key indicators and understanding their interrelationships. I am working through this process along with you, with the latest revision to my concept map. Thus far, I have examined Building Factors, Smoke Indicators, Air Track, and Heat Indicators the first fourcategories in the B-SAHF (Building, Smoke, Air Track, Heat, and Flame) organizing scheme. For review of the discussion of the work done so far, see the following Reading the Fire posts:

• 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

Focus Question

The process of developing or refining a concept map identifying fire behavior indicators (FBI) and their interrelationships starts with the following focus question:

What building, smoke, air track, heat, and flame indicators
provide clues to current and potential fire behavior?

As you develop the flame indicators concept map it is likely that you will uncover potential additions to the Building Factors, Smoke, Air Track or Heat Indicators concept maps. You may also identify interrelationships that you may not have thought of previously. Don’t forget to go back and capture these thoughts by adding them to your other maps or placing them in a staging area for further consideration.

Caution!

Flames get quite a bit of attention. Flames showing are sure to increase a firefighter’s pulse.

Figure 1. Flame Showing!

Note: Photo by Captain Jacob Brod, Pineville-Morrow Volunteer Fire Department

It is important to remember that while flames are an important fire behavior indicator, they provide only part of the picture. There is also a reason why they are last in the B-SAHF organizing scheme. Flame indicators must be integrated with Building, Smoke, Air Track, and Heat indicators to gain a more complete picture of incident conditions.

Flames

Flames are the visible, light emitting product of combustion. In compartment fires, flames are the result of glowing particulate material (predominantly carbon).

There are several distinctly different types of flames. Pre-mixed flames result when fuel vapor is mixed prior to combustion. The flame from a gas stove or heating appliance would be a good example of a pre-mixed flame. However, most of the flames encountered in a compartment fire are diffusion flames. In a diffusion flame, fuel defuses in the air to form a reaction zone containing fuel, air, and heat in the correct proportion to support combustion. Diffusion flames result from less efficient combustion (resulting in the presence of an increased percentage of unburned particulate material). The difference in appearance of pre-mixed and diffusion flames is illustrated in Figure 2.

Figure 2. Diffusion and Pre-Mixed Flames

Note: Each of these flames is being produced by the same fuel (Methane, CH4). The difference in appearance results from where the fuel and oxygen are mixed and the resulting efficiency of combustion.

Getting Started

Firefighters’ attention is often drawn to flames like a moth to a candle. However, this is only one of many fire behavior indicators. Visible flames may provide an indication of the size of the fire (i.e., fire showing from one window vs. fire showing from all windows on the floor). The size or extent of the fire may also be indicated by the effect (or lack of effect) of fire streams on flaming combustion.

As always in developing a concept map it is important to move from general concepts to those that are more specific. Flame Indicators can be divided into several categories as illustrated in Figure 3. However, you may choose to approach this somewhat differently.

Figure 3. Basic Flame Indicators

Developing the Detail

Expanding the map requires identification of additional detail for each of the fundamental concepts. If an idea appears to be obviously related to one of the concepts already on the map, go ahead and add it. If you are unsure of where it might go, but it seems important, list it off to the side in a staging area for possible additions. Download a printer friendly version of Flame Indicators to use as a starting point for this process.

Next Steps

Remember that the process of contracting your own map is likely as important as the (never quite) finished product. The following steps may help you expand and refine the flame indicators segment of the map:

• Look at each of the subcategories individually and brainstorm additional detail. This works best if you collaborate with others.
• Have a look at the following video clip using your partially completed map and notes as a guide to identifying important flame indicators. While this video clip is of conditions on the exterior, also think about how this fire would present if viewed from the interior.

The next post in this series will discuss flame indicators in greater depth.

Ed Hartin, MS, EFO, MIFireE, CFO

Reading the Fire Heat Indicators briefly examined energy, temperature, and heat in thermodynamic systems, and introduced the two major categories of heat related fire behavior indicators: those that we can see (visual) and others that can be felt (tactile) as illustrated in Figure 1.

Figure 1. Basic Heat Indicator Categories

Heat Indicators Part 2 elaborated on tactile effects. This post will examine visual effects and provide an expanded heat indicators concept map.

Remember that as with each of the B-SAHF (building, smoke, air track, heat, and flame) indicators; it is essential that assessment of heat is integrated with other elements of the B-SAHF scheme to gain a clearer sense of fire conditions and likely fire behavior.

Visual Effects

Air track often provides an early heat indicator. Observation of turbulent smoke pushing from the building at high velocity is a reliable indicator of a tremendous amount of heat energy and high temperatures inside the structure.

Figure 2. Air Track as a Heat Indicator

Note: Photo by Terry Moody, Ranlo NC.

Some visual indicators can be observed from the exterior such as bubbling paint, melting or softening roofing material, crazing glass, and condensation of pyrolyzate on windows. High temperature (and in some cases, not so high temperature) can have a more dramatic effect (see Figure 3). This vinyl frame window failed due to heat resulting from a fully developed fire inside the compartment.

Figure 3. Temperature Effects on Building Materials

Note: Photo by Ed Hartin

Fire stream effects such as evaporation of water from a hot surface (such as a door) or lack of return from a temperature check (brief application of water fog into the hot gas layer to check overhead temperature) also provide an indication of temperature (Figure 4)

Figure 4. Checking the Door and Temperature Check

Note: Photo by John McDonough

A thermal imaging camera (TIC) provides a highly effective means for visualizing temperature differences (see Figure 5). Use of a TIC should begin on the exterior and continue during interior operations.

Figure 5. Thermal Image

Note: Photo provided by Stefan Svensson

Despite the tremendous advantage provided by use of a TIC, it is essential to be mindful of the limitations of this technology. Thermal images only identify the temperature differences that are in direct line-of-sight. Insulating materials such as compartment linings can prevent the TIC from identifying fire conditions outside the compartment (e.g., floor below, ceiling void). In tests of floor and roof assemblies conducted by the Underwriters Laboratory (UL), thermal imaging cameras were unable to detect a fully developed fire below a typical wood floor (see Figure 6). The floor in Figure 6 consisted of an engineered system of I-joists, sub-floor, finished floor, carpet padding, and carpet. The floor system was being tested over a 14′ x 17′ (4.27 m x 5.18 m) gas fired furnace in accordance with ASTM E119. While the temperature indicated by the TIC is 80.1o F (27^o C), the highest temperature measured by thermocouples on the structural members was in excess of 1341o F (727^o C). It is essential to integrate thermal image data with direct visual observations to obtain a more complete picture of temperature conditions.

Figure 6. UL Floor Systems Test

Adapted from Underwriters Laboratory Structural Stability of Engineered Lumber in Fire Conditions [on-line training program]

The tests of engineered lumber systems and training program developed by UL provide excellent information on performance of these structural materials under fire conditions. This program as well as on-line training on fire behavior in single family dwellings and fire modeling are available free of charge from UL University.

Technological advancements also include temperature sensing integrated into breathing apparatus, personal alert safety systems (PASS), and even protective clothing (see Figure 7) to assist firefighters in recognizing dangerous elevated temperatures and in some cases telemetry to transmit this information to others, outside the hazardous environment. This could be viewed as a visual indicator (based on visual display of the information) or as augmentation of tactile indicators.

Figure 7. Smart Clothing by Viking Industries

Work in Progress

Hopefully we have been working on this project together and you have been developing or refining the air track segment of your fire behavior indicators concept map. My current map is illustrated in Figure 8.

Figure 8. Heat Indicators Concept Map v5.2.2.1

You can also download a printer friendly version of the Heat Indicators Concept Map v5.2.2.1 As always, should you have any suggestions or feedback, please post a comment!

Ed Hartin, MS, EFO, MIFireE, CFO

References

Underwriters Laboratory. (2009). Structural Stability of Engineered Lumber in Fire Conditions [on-line training program]. Retrieved August 27, 2009 from http://www.ul.com/global/eng/pages/offerings/industries/buildingmaterials/fire/courses/structural/

As discussed in prior Reading the Fire posts and the ongoing series examining fire behavior indicators (FBI) using the B-SAHF (Building, Smoke, Air Track, Heat, and Flame) organizing scheme, developing proficiency requires practice. This post provides an opportunity to exercise your skills using three video segments shot during a commercial fire. In addition to practicing your skill in reading the fire, use these video clips to help develop or refine your smoke indicators concept map (see Reading the Fire: Smoke Indicators).

Commercial Fire

The Lake Station (IN) Fire Department was dispatched to a reported structure fire in the vicinity of the American Legion Hall on Central Avenue. Responding companies found a commercial building with fire and smoke showing at the intersection of Central Avenue and Howard Street.

Download and the B-SAHF Worksheet.

While the video clip of this incident does not allow you to walk around the building and observe fire conditions, Google maps street view allows you to view all sides of the building. If you haven’t used street view, have a look at the following Google Street View Tutorial.

Perform a “walkaround” by clicking on the following link to view the building involved at this incident: 1691 Central Ave, Lake Station, IN. Note: Radio communication in the video clip identifies the Incident Commander as “Howard Command”. However, for this activity, I have identified Central Avenue as the A Side of the involved building. Click on the arrows to move east on Central Avenue and move and adjust the compass rose to look at Side D. Move back along Central Avenue and then go down Howard Street, again adjusting the compass rose to look at Sides B and C. After your “walk around”, complete the Building Factors segment of the B-SAHF Worksheet.

The video clip of this incident begins with the view of Side B from the A/B Corner prior to the arrival of the first engine company. 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 (add to what you have done so far), 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?

Watch the next three minutes of the video and identify if, and how conditions change from the beginning of the clip until the first line is placed in operation (at approximately 04:00).

Watch the next 2 minutes 30 seconds until the firefighters make entry through the door on Side A (at approximately 06:30).

1. What conditions would you expect to find inside this part of the building?
2. How would you expect the fire to develop over the next two to three minutes?

Watch the remainder of the video clip.

Important: While not related to Reading the Fire, you likely heard the Personal Alert Safety System (PASS) device sounding through much of the incident. While PASS devices can (and often are) accidentally activated, continuous sounding of a PASS indicates a firefighter in distress. While this was not the case in this incident, failure to silence PASS devices that are accidentally activated desensitizes firefighters to this important audible signal.

Remember the Past

August 1994 saw the loss of two company officers and a firefighter in three separate incidents involving extreme fire behavior. Rapidly changing fire conditions are a threat to firefighters working in career staffed, urban fire departments and volunteer departments serving small communities.

August 7, 1994
Captain Wayne Smith
Fire Department of the City of New York, New York

On August 7, Captain Wayne Smith of the New York City Fire Department was critically injured while conducting search and rescue operations on an upper floor of a building when he was trapped by high heat and heavy smoke conditions. Captain Smith was burned over 40 percent of his body and received severe smoke inhalation injuries to his lungs. He died on October 4 from his injuries. Fourteen other firefighters were injured in the blaze. Initial operations were hampered by a faulty fire hydrant across the street from the building.

August 8, 1994
Sergeant Craig Drury
Highview Fire District, Kentucky

On August 8, Sergeant Craig Drury of the Highview (KY) Fire District was caught in a flashover while making entry into a single story house. Sgt. Drury suffered severe burns to his lungs that eventually caused his death. The fire was started by an arsonist.

August 27, 1994
Firefighter Paul MacMurray
Hudson Falls Volunteer Fire Department, New York

On August 27, Firefighter Paul MacMurray of the Hudson Falls (NY) Volunteer Fire Department responded as part of an engine company to a fire on the first floor of in a three story hotel. Assigned to search for and rescue occupants on the second floor, MacMurray and another firefighter successfully evacuated several victims while attempts to extinguish the fire were initiated below them. Upon their return to continue the search, conditions quickly changed from a light haze of smoke to black smoke with high heat conditions. MacMurray and his partner became separated in their attempt to locate the stairwell and get out of the building. The other firefighter made several efforts to locate MacMurray, but was forced to retreat due to untenable conditions. Several rescue efforts were made but heavy fire conditions eventually forced the evacuation of all fire personnel to defensive positions as the entire structure burned. MacMurray’s body was recovered the following day. The fire was of incendiary origin.

Ed Hartin, MS, EFO, MIFIreE, CFO

Reading the Fire Heat Indicators briefly examined energy, temperature, and heat in thermodynamic systems, and introduced the two major categories of heat related fire behavior indicators: those that we can see (visual) and others that can be felt (tactile) as illustrated in Figure 1.

Figure 1. Basic Heat Indicator Categories

As with each of the B-SAHF (building, smoke, air track, heat, and flame) indicators, it is essential that assessment of heat is integrated with other elements of the B-SAHF scheme to gain a clearer sense of fire conditions and likely fire behavior.

The Thermal Environment

The thermal environment that firefighters encounter can be complex, but involves one or more of the following scenarios (Bryner, Madrzykowski, & Stroup, 2005):

• Immersion in a relatively static layer of hot gases (i.e., crawling or crouching in a room full of hot combustion products and smoke)
• Contact with a moving layer of hot gases (i.e., entry through a door or moving down a hallway with a strong air track)
• Exposure to radiant heat (i.e., working in proximity to flames or below a layer of hot gases)

Figure 2 illustrates the variations in temperature that firefighters may encounter during operations in a highly compartmentalized, multi-level structure. It is important to note that temperature varies from compartment to compartment and at different levels within each compartment.

Figure 2. Smokeview Slice

Note: Adapted from National Institute of Standards and Technology (NIST) Visualization techniques, Slice animation of a townhouse kitchen fire.

Firefighters’ personal protective equipment insulates them from the thermal environment. This layer of insulation makes it difficult to accurately assess temperature and heat flux (amount of heat transfer) that they are exposed to during firefighting operations. The thermal insulation provided by personal protective equipment slows, but does not stop heat transfer from the fire environment to the firefighter. Thermal exposure is dependent on gas temperature and radiant heat flux (heat transfer due to radiation)./

Thermal exposure can be divided into four categories: Ordinary, Hazardous, Extreme, and Critical (Foster & Roberts, 1995; Donnelly, Davis, Lawson, J., Selpak, 2006). As illustrated in Figure 3.

Figure 3. 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.

Several challenges confront firefighters in assessing the thermal environment during firefighting operations. These include:

• Of necessity, firefighters are insulated from their environment, delaying tactile perception of changes in temperature and heat flux.
• Perception of temperature is influenced by a wide range of factors and varies considerably from individual to individual.
• Firefighters focused on the task at hand may not notice subtle changes in temperature and heat flux.
• Temperature and heat flux do not always present obvious visual indicators.
• Conditions can change extremely rapidly, particularly as the fire approaches flashover.
• Firefighters may ignore warning signs of worsening conditions, believing that it is part of the job to tolerate extreme conditions.

Firefighters must have a sound understanding of the thermal environment encountered during firefighting operations and the, at times, subtle indicators of changing thermal conditions.

Tactile Effects

Tactile effects include sensing temperature or temperature change. Firefighters may sense temperature and changes in temperature, but as noted earlier, this is limited by the extent of thermal protection provided by their protective clothing and focus on the task at hand. Firefighters’ protective clothing effectively insulates them from the thermal hazards typically encountered in firefighting. The multiple layers of insulation in the protective ensemble slows (but does not stop) heat transfer. This time lag makes it difficult for the firefighter to appreciate their thermal exposure (Bryner, Madrzykowski, & Stroup, 2005).

Firefighter’s personal alert safety system (PASS) devices may be equipped with a temperature sensing function that provides warning at a specified exposure value when the specified temperature is exceeded for a specified time period (Figure 4). However, National Fire Protection Association 1982 Standard on Personal Alert Safety Systems (PASS) (NFPA, 2007) does not address thermal sensing and there is not standardized test protocol for these types of devices (Bryner, Madrzykowski, & Stroup, 2005). Thermal sensing devices use a temperature response curve to provide warning for long duration exposure to lower temperature and short duration exposure to higher temperature. However, during rapid increases in temperature such as those encountered in flashover or other forms of rapid fire development, adequate early warning to permit egress is unlikely due to limited sensitivity of the sensors (Bryner, Madrzykowski, & Stroup, 2005). While firefighters must be attentive to heat level and temperature change, it is often difficult to perceive these changes quickly enough to react to rapidly developing fire conditions. This reinforces the importance of integrating all the fire behavior indicators in your ongoing size-up and dynamic risk assessment.

Figure 4. PASS Device Temperature Sensor

Next Steps

The next post will conclude this look at Heat Indicators with examination of visual effects. While temperature and heat transfer cannot be observed directly, there are a number of ways in which firefighters can see the effects of temperature and heat.

Ed Hartin, MS, EFO, MIFireE, CFO

References

Bryner, N., Madrzykowski, D., Stroup, D. (2005). Performance of thermal exposure sensors in personal alert safety system (PASS) devices, NISTR 7294. Retrieved August 19, 2009 from http://www.fire.nist.gov/bfrlpubs/NIST_IR_7294.pdf.

Donnelly, M., Davis, W., Lawson, J., & Selpak, M. (2006). Thermal environment for electronic equipment used by first responders, NIST Technical Note 1474. Retrieved August 19, 2009 from http://www.fire.nist.gov/bfrlpubs/fire06/PDF/f06001.pdf

National Institute of Standards and Technology (NIST) Visualization techniques, Slice animation of a townhouse kitchen fire, [digital video file]. Retrieved August 19, 2009 from http://www.fire.nist.gov/fds4/refs/thouse3/thouse3_slice.avi

In 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. Construction of a concept map increases awareness of key indicators and understanding their interrelationships. I am working through this process along with you, with the latest revision to my concept map. Thus far, I have examined Building Factors, Smoke Indicators, and Air Track Indicators, the first three categories in the B-SAHF (Building, Smoke, Air Track, Heat, and Flame) organizing scheme. For review of the discussion of the work done so far, see the following Reading the Fire posts:

• Building Factors
• Building Factors Part 2
• Building Factors Part 3
• Smoke Indicators
• Smoke Indicators Part 2
• Air Track Indicators
• Air Track Indicators Part 2

Focus Question

The process of developing or refining a concept map identifying fire behavior indicators (FBI) and their interrelationships starts with the following focus question:

What building, smoke, air track, heat, and flame indicators
provide clues to current and potential fire behavior?

As you develop the heat indicators concept map it is likely that you will uncover potential additions to the Building Factors, Smoke, or Air Track Indicators concept maps. You may also identify interrelationships that you may not have thought of previously. Don’t forget to go back and capture these thoughts by adding them to your other maps or placing them in a staging area for further consideration.

Heat and Temperature

Firefighters, like everyone else, have a commonsense understanding of heat and temperature. This is likely where many of our challenges in really understanding thermodynamics begins. The way in which we use the concepts of heat and temperature on a daily basis are likely to be considerably different than they are used in science.

Thermodynamics is a branch of physics that describes processes that involve changes in temperature, transformation of energy, and the relationships between heat and work. Fires and firefighting also involves changes in temperature, transformation of energy, heat and work. “Thermodynamics, like much of the rest of science, takes terms with an everyday meaning and sharpens them – some would say, hijacks them – so that they take on an exact an unambiguous meaning” (Atkins, 2007, p. 3).

Thermodynamics deals with systems. A thermodynamic system is one that interacts and exchanges energy with the area around it. A system could be as simple as a block of metal or as complex as a compartment fire. Outside the system are its surroundings. The system and its surroundings comprise the universe. For example we might consider a burning fuel package as the system and the compartment as the surroundings. On a larger scale we might consider the building containing the fire as the system and the exterior environment as the surroundings.

Figure 1. Thermodynamic Systems

In a compartment fire, energy is exchanged within the thermodynamic system and between the system and its surroundings.

Energy is the ability to do mechanical work or transfer thermal energy from one object to another. Energy can only be measured on the basis of its effects. There are basically two kinds of energy, kinetic and potential. Potential energy is that which is stored and may be released at a later time. The chemical energy contained in fuel that can be released during combustion is one example of potential energy. Kinetic energy is associated with motion of an object. Movement of molecules when heated during combustion is a good example of kinetic energy. Temperature is a measure of average kinetic energy.

The word flow is often used in discussing heat transfer (e.g., energy flows from materials with higher temperature to those with lower temperature). This helps visualize patterns of movement, but it is important to remember that neither energy nor heat is a fluid. Heat is the process of energy transfer due to temperature differences.

It is important to remember that we cannot see energy, temperature, or heat. However, we can see and feel the impact of increases in temperature as a result of heat (energy transfer). Use of the word heat to describe this category of indicators is appropriate as these indicators are all related to transfer of energy within and out of the compartment fires thermodynamic system.

Getting Started

When reading the fire it is important not to focus on a single indicator or category of indicators. In the case of heat, there are many interrelationships with air track and flame indicators. In some cases, it is arguable whether an indicator belongs in one category or the other (likely it is not important as long as you recognize the interrelationships).

As always in developing a concept map it is important to move from general concepts to those that are more specific. Heat Indicators can be divided into two basic categories, those that you can see (visual effects) and those that you can feel (tactile effects) as illustrated in Figure 2. However, you may choose to approach this somewhat differently.

Figure 2. Basic Heat Indicators

Developing the Detail

Expanding the map requires identification of additional detail for each of the fundamental concepts. If an idea appears to be obviously related to one of the concepts already on the map, go ahead and add it. If you are unsure of where it might go, but it seems important, list it off to the side in a staging area for possible additions. Download a printer friendly version of Heat Indicators to use as a starting point for this process.

Next Steps

Remember that the process of contracting your own map is likely as important as the (never quite) finished product. The following steps may help you expand and refine the building factors segment of the map:

• Look at each of the subcategories individually and brainstorm additional detail. This works best if you collaborate with others.
• Have a look at the following video clip using your partially completed map and notes as a guide to identifying important heat indicators. While this video clip is of conditions inside a compartment, also think about how this fire would present if viewed from the exterior.

The following video clip illustrates a recreation of the Station Night Club Fire that occurred in Rhode Island in 2003 that was conducted at the National Institute of Standards and Technology (NIST) laboratory in Gaithersburg, MD

The next post in this series will discuss visual and tactile heat indicators in greater depth and examine the increasing influence of technology in our perception (and misperception) of developing fire conditions.

Ed Hartin, MS, EFO, MIFireE, CFO

References

Atkins, P. (2000). Four laws that drive the universe. Oxford, UK: Oxford University Press