Archive for the ‘Random Thoughts’ Category

The Chemical History of a Candle-Revisited

Sunday, December 22nd, 2013

English scientist Michael Faraday initiated The Royal Institution Christmas Lectures in 1825. These lectures which have been held at the Royal Institution in London each year since 1825, with the exception of 1939-1942 are an entertaining and informative presentation of scientific subjects. In 1848, Faraday conducted a series of lectures titles The Chemical History of a Candle (read on-line here).

Chemical History of a Candle

Faraday conducted a series of demonstrations during this lecture series that are still used by fire behavior instructors today. As Christmas approaches, I spent some time reading The Chemical History of a Candle and thinking about how we develop Firefighters understanding of fire behavior. Poking about   on YouTube, I came across a more recent Christmas lecture at the Royal Institution in which Ian Russell examined Faraday’s lecture on The Chemical History of a Candle and the creative tension between explanation and exploration in hands on science. I suspect that we spend far too much effort on explanation and too little on exploration. Developing Firefighters knowledge of fire behavior and their curiosity about the underlying science might be better served with a larger dose of exploration… If you teach fire behavior, take an hour and watch Ian Russell’s lecture.

Thanks to Ian Bolton for reminding me of another great resource on the topic: Understanding Fire Through the Candle Experiments on the International Association of Arson Investigators CFITrainer.net website (which also has other excellent fire dynamics resources).

In 2014, I will be working on the concept of a learning laboratory which will allow development of Firefighters understanding of practical fire dynamics by shifting the balance from explanation to exploration and encourage all of you to contribute to this process! Have a Happy Holiday season, remain curious, and keep learning! Ed Hartin

Theory and Practice

Sunday, August 11th, 2013

Recently I have been following a series of discussions on Facebook on the relative merits of compressed air foam (CAF) versus water as an extinguishing agent. Some of my colleagues profess that CAF is superior in all respects and in all applications for extinguishment by cooling. Others point to the limited ability to cool hot gases when dealing with a shielded compartment fire as a major problem with CAF and where water is the superior agent for fire control.

cafs_water_3

Knowledge and Belief

As I have followed and occasionally participated in this discussion about CAF and water, I began to think about why we believe what we do (and the difference between belief and knowledge). Some of us are zealots who are fanatically committed to a particular perspective. In this case, belief does not require evidence (or evidence is seen through a lens that supports existing belief and all else is dismisses or disregarded). Some of us are skeptics who instinctively doubt, question, or disagree with generally accepted conclusions. Some of us accept information provided from sources that we consider authoritative, while others think critically, weighing evidence in deciding if a claim is always true, sometimes true, partially true, or false regardless of the source.

Historical Perspective

It is interesting that the fire service in the 21st century is engaged in a concerted effort to integrate theory and practice, research with the fire service conducted by Underwriters Laboratories (UL), National Institute of Standards and Technology (NIST) as well as universities, government agencies, and fire services from around the world. We continue to struggle with moving from practical knowledge based on observation and information passed from earlier generations of firefighters to evidence based practice where practical decisions are made based on research that is valid and reliable. There may be some lessons in the 19th century writing of Massey Shaw, the first Chief Fire Officer of the Metropolitan London Fire Brigade:

In a new profession, all measures are necessarily in some degree tentative. It is only the superficial and half-educated who, in such cases, announce everything in detail beforehand, and thus find themselves, for years afterwards, working in a false position, endeavoring, contrary to experience and their improved information, to justify announcements made by them while laboring under that most unsatisfactory, but perhaps most common, form of ignorance, which consists of practical knowledge, absolutely alone, without the aid of theory, and which is consequently to a great extent antagonistic to all useful developments.

To those who have not studied the principles of true and useful progress, this statement may seem a paradox, but it really is nothing of the kind. Theoretical knowledge is essentially progressive; it suggests new modes of doing everything; and, even where absolutely new odes are proved to be impracticable, it suggests modifications and alterations of existing modes, an devises schemes for meeting every possible objection which can be urged. Practical knowledge alone, unaided by theory, is, on the contrary, from its very nature, obstructive to the last degree’ it makes objections to everything not actually proved to demonstration, and, in short, considers nothing possible that has not been already accomplished. Then there are the innumerable imperfect combinations of theory and practice, which, as long as they remain imperfect, produce the worse consequences of all.

How often do we see a man, eminently practical in all respects, and whose opinion on any practical matter connected with his ordinary business is worthy of the highest consideration, suddenly seized with an idea, which, being unaided by education, develops itself into a theory of the wildest kind, involving those who follow it in utter ruin – and all because the supposed theory turns out to be no true theory at all, and nothing better than the excrescence of an uneducated or eccentric intellect. And again, how often do we see theory along, however sound in itself, utterly prostrate and rendered worthless, through flying too wildly for want of the obstructive and steadying power of practice (Shaw, 1868, vii)

Moving Beyond Simple Experience

Kurt Lewin, a social psychologist observed “There is nothing so practical as a good theory” (Lewin, 1951, p. 169). He expands on this idea, observing that theory makes it possible to move beyond simple collection and description of facts by characterizing what is behind those observations. Theory helps us make sense of practical experience.

As firefighters and fire officers in the 21st century, we need to move beyond simple experience and integrate a sound understanding of the theory of fire dynamics and fire control. Similarly, we need to be wary of theory alone, and integrate practical experience with scientific research and underlying theoretical concepts. Both are necessary, but neither is sufficient.

generic cialis online Be curious, think critically, and learn continuously!

References

Lewin, K. (1951). Field theory in social science. New York: Harper Brothers.

Shaw, M. (1868) Fire protection: A complete manual of the organization, machinery, discipline, and general working of the fire brigade of London. London: Charles and Edwin Layton

What’s on Side C

Sunday, May 19th, 2013

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

View from the Street

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

need_and_feed_side_a_small

Reconnaissance on Side C

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

need_and_feed_side_c_small

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

The Rest of the Story

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

need_and_feed_side_a_small_annotated

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

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

need_and_feed_side_c_small_annotated

Strategic and Tactical Implications

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

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

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

Thanks!

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

Influence of Ventilation in Residential Structures: Tactical Implications Part 2

Saturday, June 18th, 2011

Is making entry with a hoseline for fire attack, ventilation? Is entering through a doorway when conducting search, ventilation? While many firefighters do not think about ventilation when performing these basic fireground tasks, the answer is a resounding yes!

Making Entry is Ventilation

While the Essentials of Firefighting (IFSTA, 2008) defines ventilation as “the systematic removal of heated air, smoke, and fire gases from a burning building and replacing them with cooler air” [emphasis added] (p. 541), the main focus of most ventilation training is on the exhaust opening. In discussing compartment fire development, the 6th Edition of Essentials (IFSTA, 2008) includes a discussion of the concept of fuel and ventilation controlled burning regimes. In addition, the section of the text addressing the positive effects of ventilation such as reducing potential for flashover and backdraft, Essentials (IFSTA, 2008) cautions that increasing ventilation to ventilation limited fires may result in rapid fire progression. However, these concepts were not included in earlier additions and the connection between openings made for the purpose of ventilation and openings made for other reasons is often overlooked.

Ventilation versus Tactical Ventilation

Despite the definitions given in fire service text that describe ventilation in terms of actions taken by firefighters, ventilation is simply the exchange of the atmosphere inside a building with that which is outside. Normal air exchange between the interior and exterior of a building is expressed as the number of complete air exchanges (by volume) per hour and varies depending on the purpose and function of the space. In residential structures, the air in the building is completely exchanged approximately four times per hour. In commercial and industrial buildings this rate may be significantly higher, depending on use. When firefighters arrive to find smoke issuing from a building, ventilation is occurring and when firefighters open a door to make entry, the ventilation profile changes as ventilation has been increased. Remember:

  • If smoke exits the opening (air is entering somewhere else) ventilation is occurring.
  • If air enters the opening (smoke is exiting somewhere else), ventilation is occurring.
  • If smoke exits and air enters the opening ventilation is occurring.

The entry point is a ventilation opening and if the fire is ventilation controlled, any ventilation opening will increase heat release rate (HRR)!

Ventilation Controlled Fires

As discussed in Influence of Ventilation in Residential Structures: Tactical Implications Part 1 [LINK], compartment fires that have progressed beyond the incipient stage are likely to be ventilation controlled when the fire department arrives. Firefighters and fire officers must recognize the potential for a rapid increase in HRR when additional atmospheric oxygen is provided to ventilation controlled fires. This is particularly important when considering door entry and door control during fire attack, search, and other interior operations. The Underwriters Laboratories (UL) research project Impact of Ventilation on Fire Behavior in Legacy and Contemporary Residential Construction (Kerber, 2011) examined fire behavior in a small, single-story, wood frame house and a larger, two-story, wood frame house (see Figures 1 & 2) Figure 1. Single-Story Legacy Dwelling

Figure 2. Two-Story Contemporary Dwelling

Each of the fires in these experiments occurred in the living room (one-story house) or family room (two-story house). While the fuel load was essentially the same, the family room had a much greater volume as it had a common cathedral ceiling with an atrium just inside the front door. Experiments one and two examined fire behavior in each of these structures with the front door being opened at the simulated time of arrival of the fire department. Figure 3 illustrates the changes in temperature during UL Experiment 1 (Single Story-Door as Vent Opening) and Experiment 2 (Two-Story-Door as Vent Opening). Figure 3. Living/Family Room Temperature Curves-Door as Ventilation Opening

As illustrated in Figure 3, temperature conditions changed dramatically and became untenable shortly after the front door was opened. In the one-story experiment (Experiment 1) temperature:

  • Was 180 °C (360 °F) at ventilation (480 s),
  • Exceeded the firefighter tenability threshold of 260 °C (500 °F) at 550 s
  • Reached 600 °C (1110 °F) at 650 s and transitioned through flashover to a fully developed fire in the living room

In the two-story experiment (Experiment 2) temperature:

  • Was 220 °C (430 °F) at ventilation (600 s)
  • Exceeded the firefighter tenability threshold of 260 °C (500 °F) at 680 s
  • Reached 600 °C (1110 °F) at 780 s and transitioned through flashover to a fully developed fire in the family room

When the door is opened the clock is ticking! HRR will increase and the tenability within the fire compartment and adjacent spaces will quickly deteriorate unless water can be applied to control the fire. Keeping the door closed until ready to make entry delays starting the clock. Closing the door after entry (leaving room for passage of your hoseline) slows fire development and buys valuable time to control the fire environment, locate the fire, and achieve fire control.

Just as in the UL experiments on the influence of ventilation in residential structures, heat release rate will increase and fire conditions can change dramatically when a door is opened for access and entry.

In 2008, two firefighters from the Riverdale Volunteer Fire Department in Prince Georges County Maryland recently were surprised by a flashover in a small, single family dwelling. In the first photo, firefighters from Engine 813 and Truck 807 prepare to make entry. Note that the front door is closed, the glass of the slider and windows are darkened, and smoke can be observed in the lower area of the front porch. Six seconds later it appears that the front door has been opened, flames are visible through the sliding glass door, and the volume of smoke in the area of the porch has increased. However, the smoke is not thick (optically dense). Forty eight seconds later, as the crew from Truck 807 makes entry to perform horizontal ventilation the volume of smoke from the front door increases and thickens (becomes more optically dense).

Figure 4. Ventilation Induced Flashover-Door as a Ventilation Opening

Note: Photos by Probationary Firefighter Tony George, PGFD The crew from Engine 813 experienced a burst hoseline, delaying fire attack. Two minutes after the first photo, and shortly after the crew from Truck 807 made entry, flashover occurred. For additional information on this incident, see Situational Awareness is Critical.

Door Control

The issue of door control presents a similar (and related) paradox as ventilation. Ventilation is performed to improve interior tenability and to support fire control, but when presented with a ventilation controlled fire, increased air supply increases HRR and can result in worsening tenability and potential for extreme fire behavior. Firefighters often chock doors open to provide ease of hoseline deployment and an open egress path, but when the fire is ventilation controlled, this (ventilation) opening starts the clock on increased HRR and rapid fire development. It is useful to consider door control in two phases, door entry procedures and control of the door after entry.

Size-Up: Door entry begins with a focused size-up as you approach the building. Assessment of conditions is not only the incident commander or officer’s job. Each member entering the building should perform a personal size-up and predict likely conditions. When making entry, size-up becomes more closely focused on conditions observed at or near the door and includes an assessment of potential forcible entry requirements as well as B-SAHF (Building-Smoke, Air Track, Heat, and Flame) indicators. If available, a thermal imaging camera (TIC) can be useful, but remember that temperature conditions may be masked by the thermal characteristics of the building. If a thermal imaging camera is not available, application of a small amount of water to the door may indicate temperature and the level of the hot gas layer (water will vaporize on contact with a hot door).

Size-up begins as you exit the apparatus and approach the building, but continues at the door and after you make entry!

At the door, pay close attention to air track and heat (door temperature) indicators as these can provide important clues to conditions immediately inside the building!

Prior to Entry: If the door is open, close it. If it is closed, don’t open it until you are ready. If the door is unlocked, control is generally a simple process (see Nozzle Techniques and Hose Handling: Part 3 for detailed discussion of door entry when the door is unlocked).

If the door is locked and must be forced, this adds an element of complexity to the door entry process. In selecting a forcible entry method, consider that the door must remain intact and on its hinges if you are going to maintain control of the air track at the opening.

This is fairly easy with outward opening doors. Inward opening doors present a greater challenge. A section of webbing or rope can be used to control an inward door by placing a cinch hitch around the door knob (see Figure 5). As the the door is forced, it can be pulled closed. However, if the door was not locked with a deadbolt, it may re-latch when pulled closed. Figure 5. Door Control with Web or Utility Rope

Figure 5. Door Control with Webbing or Utility Rope

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Alternately, a Halligan or hook may be used to capture the door and pull it substantially closed after it is forced (see Figure 6).

Figure 6. Door Control with a Tool

If B-SAHF (Building, Smoke, Air Track, Heat, & Flame) indicators point to hazardous conditions on the other side of the door, forcible entry must be integrated with good door entry procedure to control potential hazards. After Entry: The most effective way to control the door after entry and provide ease of egress is to have a firefighter remain at the opening to control the door and feed hose to the hose team working inside (see Figure 7).

Figure 7. Door Control After Entry

Note: The Firefighter maintaining door control would be wearing complete structural firefighting clothing and breathing apparatus (this is simply an illustration of door control with a hoseline in place)!

Unfortunately, many companies do not have sufficient staff to maintain a nozzle team of two and leave another firefighter at the door. In these cases, it may be possible for the standby firefighters (two-out) to control the door for the crew working inside until additional resources are available.

Nozzle Technique & Hose Handling

Prior posts on nozzle technique and hose handling included a series of drills to develop proficiency in critical skills.

Review these nine drills and then extend your proficiency by integrating forcible entry with good door entry procedure by maintaining control of the door.

Drill 10-Door Entry-Forcing Inward Opening Doors: Many doors (particularly interior and exterior residential) open inward. In this situation forcible entry, door control, and nozzle operation must bee closely coordinated. Practicing these techniques under a variety of conditions (e.g., wall locations, compartment sizes) is critical to developing proficiency.

Drill 11-Door Entry-Forcing Outward Opening Doors: Commercial (and some interior residential doors) open outward. While less complex, Firefighters must develop skill in integration of forcible entry, door control, and nozzle technique in this situation as well.

Hose Handling and Nozzle Technique Drills 11 & 12 Instructional Plan

In both of these drills, focus on maintaining control of the door during forcible entry and limit air intake by keeping the door as closed as possible while passing the hoseline as it is advanced.

References

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

International Fire Service Training Association (IFSTA). (2008) Essentials of firefighting (6th ed.). Stillwater, OK: Fire Protection Publications.

Influence of Ventilation in Residential Structures:
Tactical Implications Part 1

Sunday, February 6th, 2011

UL Research on the Impact of Ventilation on Fire Behavior

Earlier this year, Underwriters Laboratories (UL) conducted a series of full-scale experiments to determine the influence of ventilation on fire behavior in legacy and contemporary residential construction (see Did You Ever Wonder?).

UL University recently released an excellent on-line training program based on this research. In addition to the on-line course, UL has published a comprehensive report on this important project: Impact of Ventilation on Fire Behavior in Legacy and Contemporary Residential Construction (Kerber, 2011).

This series of posts will examine twelve tactical implications identified by UL in the research report and on-line course.

Burning Regime and Stages of Fire Development

As illustrated in Figure 1, the traditional fire development curve used to illustrate changes in heat release rate and temperature over time as a compartment fire develops shows ignition and the incipient stage of fire development followed by growth, a fully developed fire, and decay. While this is reasonably representative of combustion of a single fuel package under unconfined and well ventilated conditions, it often does not reflect the reality of today’s fire environment as illustrated by a near miss in Springfield, VA on January 22, 2011. Three firefighters from Fairfax County Fire Rescue were caught in flashover which occurred after initial firefighting operations were commenced in a two-story townhouse.

On February 4, 2011, five firefighters in New Hyde Park, NY were caught by rapid fire progression while advancing a hoseline into a basement fire in a single family dwelling (more information here).

These incidents point to the importance of a sound understanding of practical fire dynamics and the influence of ventilation on fire behavior.

In the contemporary fire environment, fires progress from ignition and incipient stage into growth, but here is where things change. Instead of progressing through growth to the fully developed stage, fires often become ventilation controlled and begin to decay. Decay continues until the ventilation profile changes (e.g., window failure due to fire effects, opening a door for entry or egress, or intentional creation of ventilation openings by firefighters. When ventilation is increased, heat release rate again rises and temperature climbs with the fire potentially transitioning through flashover to a the fully developed stage.

Figure 1. Fire Development in a Compartment

Oxygen Consumption and Energy Release

That the energy released by combustion is related to the oxygen consumed in the reaction is not a new idea: “The door should be kept shut while the water is being brought, and the air excluded as much as possible, as the fire burns exactly in proportion to the quantity of air which it receives” (Braidwood, 1866, p. 64). For the time, James Braidwood, first Chief of the City of London Fire Brigade had a remarkable understanding of combustion. Despite this practical understanding of oxygen and release of energy through combustion, it wasn’t until 50 years later that this relationship was quantified. In 1917, British scientist W.M. Thornton discovered that while the heat of combustion of various types of organic (carbon based) fuel varies widely, the amount of oxygen required for release of a given amount of energy remains remarkably consistent (Thornton, 1917).

While the heat release of 13.1 MJ/kg (13.1 kJ/g) of oxygen consumed during combustion is often referred to as Thornton’s Rule, discovery of this concept and quantification of this value under a variety of conditions was the work of a number of individuals. For example, in the 1970’s, researchers at the National Bureau of Standards (now the National Institute of Standards and Technology, NIST) independently discovered the same thing and extended this work to include many other types of organic materials and examined both complete and incomplete combustion (Parker, 1977; Huggett, 1980).

Heat release during combustion is dependent on oxygen. However, the atmosphere is comprised of only 21% oxygen. Examining the relationship between consumption of atmospheric oxygen and energy release requires adaptation of Thornton’s Rule based on oxygen concentration. Multiplying 13.1 MJ/kg of oxygen by 21% gives a value of 2.751 MJ/kg of air. The Society of Fire Protection Engineering (SFPE) Handbook of Fire Protection Engineering (SFPE, 2002) rounds this value to 3.0 MJ/kg of air. While it is easy to understand that air has mass, it may be a bit more difficult to visualize a kilo of air! The density of dry air at sea level and at a temperature of 20o C is 1.2 kg/m3 (0.075 lbs./ft3). Air density decreases as temperature or moisture content of the air increases, but this provides a starting point for visualizing the relationship between volume and mass at normal temperature and pressure.

As illustrated in Figure 1, multiplying the mass of a cubic meter of air (1.2 kg) by the energy released per unit mass of air (3.0 KJ/kg) provides an approximation of the energy released when the oxygen in one cubic meter of air is consumed in a combustion reaction.

Figure 2. Energy Release per Cubic Meter of Dry Air

Oxygen to support energy release resulting from combustion occurring within a closed compartment is substantially (but not entirely) limited to the mass of air in the compartment. Normal air exchange between the interior and exterior of a building is expressed as the number of complete air exchanges (by volume) per hour and varies depending on the purpose and function of the space. In residential structures, the air in the building is completely exchanged approximately four times per hour. In commercial and industrial buildings this rate may be significantly higher, depending on use.

Designed air exchange and leakage provide additional oxygen that can support ongoing combustion, but this is generally not a major factor in buildings where the windows and doors are closed and intact.

Oxygen Concentration and Ventilation Controlled Fires

Energy release as a result of combustion is directly proportional to the oxygen consumed in the reaction. However, when a fire is burning in an oxygen limited environment such as an enclosed space, not all of the oxygen can be used to support flaming combustion. As observed by Mowrer, “A diffusion flame immersed in a vitiated [oxygen limited] atmosphere will extinguish before consuming all the available oxygen from the atmosphere” (McGrattan, Hostikka, Floyd, Baum, & Rehm, 2008, p. 85).

As oxygen within a compartment is consumed, fire growth becomes limited by ventilation (inclusive of the air within the compartment at ignition and the ongoing air exchange). Ventilation becomes the dominant factor in fire development when the oxygen concentration is between 14 and 16 %.

Oxygen Concentration and Flaming Combustion

As temperature increases, the oxygen concentration required to support flaming combustion decreases. Figure 3 illustrates the relationship between gas temperature and the concentration of oxygen required to support flaming combustion. Keeping in mind that temperature within involved and adjacent compartments can vary considerably, flaming combustion may be possible in some areas and not in others.

Figure 3. Oxygen Concentration Required for Flaming Combustion

Note: Adapted from Fire Dynamics Simulator (Version 5) Technical Reference Guide (p. 25), by K. McGrattan, S. Hostikka, J. Floyd, H Baum, & R. Rehm, 2008, National Institute of Standards and Technology.

Oxygen concentration required to support flaming combustion varies over a wide range based on temperature.  However, in examining fire development in a single compartment or a residential structure, it is reasonable to use the value of 10.5% as the concentration required to support flaming combustion based on the fairly consistent temperatures of between 500o C and 600o C developed prior to ventilation (window failure, opening a door for access, or tactical ventilation operations). This assumption is based on analysis of the data from full scale residential fire tests conducted by Underwriters Laboratories in representative legacy and contemporary structures (Kerber, 2011).

Limitations on Fire Development in a Single Compartment

A fire in a single, small compartment with no openings (window and door closed) provides a simple example of the impact of limited oxygen on fire development. To estimate the potential for development of a ventilation limited conditions, the available oxygen must be compared to the oxygen that would likely be consumed during combustion of typical contents.

Figure 4. Single Compartment

As illustrated in Figure 4, a 3 m x 4 m x 2.44 m (9’ 10” x 13’ 1” x 8’) compartment contains 30 m3 (1059.44 ft3) of air. Given the oxygen concentration required for flaming combustion under conditions typically encountered in a developing fire (10.5 % O2 at a temperature of 600o C), half of this volume, 15 m3 (529.72 ft3) would be available to support flaming combustion in a rapidly developing fire. Multiplying 15 m3 x 3.6 MJ/m3 of dry air indicates that the total energy release before flaming combustion is substantially reduced or ceases is approximately 46.8 MJ.

A single wood and polyurethane upholstered chair (such as a recliner) is likely to have a heat of combustion of approximately 18 MJ/kg and have a mass of 28 kg (Bukowski, 1985). Multiplying the heat of combustion by the mass identifies the total potential energy of this single fuel package as being approximately 504 MJ, well in excess of the potential energy release provided by the oxygen available in the 3 m x 4 m x 2.44 m (9’ 10” x 13’ 1” x 8’) compartment.

While a single fuel package such as an upholstered chair provides sufficient fuel to develop a ventilation limited fire, the fuel load in a normal residential compartment is likely to be substantially greater. International Fire Engineering Guidelines indicate the 95% fractile fuel load for dwellings may be estimated as 970 MJ/m2 (95% of dwellings will have a value at or below this level) (Bukowski, 2006). Multiplying the compartment floor area 12 m2 by 970 MJ/m2 provides an estimated total fuel load of 11,640 MJ. This indicates that there is far less atmospheric oxygen in the compartment than required to fully oxidize the likely fuel load.

Joules are a measure of energy, in this case a measure of total energy released by the combustion reaction. This is important, but even more important is the energy released per unit of time or heat release rate (HRR).

Some fires develop slowly, consuming oxygen at a correspondingly slow rate. However, as illustrated in Figure 3 fires involving many contemporary furnishings develop quite quickly.

Figure 5. T2 Fire Development Curves

At a HRR of 0.5 MW (500 kW), a fire in the 3 m x 4 m x 2.44 m (9’ 10” x 13’ 1” x 8’) compartment illustrated in Figure 4, would become ventilation limited to the point where flaming combustion would be significantly diminished or cease in less than two minutes. As the fire develops and HRR increases, the time for the fire to become ventilation controlled and enter the decay stage becomes considerably less.

Calculation of the energy release or time to become ventilation controlled and enter the decay stage based on the volume of the room does not account for normal building ventilation (exchange of the atmosphere inside the building with that on the outside). With an exchange of four times per hour, the 3 m x 4 m x 2.44 m (9’ 10” x 13’ 1” x 8’) compartment containing 30 m3 (1059.44 ft3) of air would have an air exchange rate of 0.033 m3/s (1.65 ft3/s). Multiplying the 0.033 m3 of air exchanged per second by 3.6 MJ/m3 (of dry air) indicates that the normal air exchange would support an ongoing HRR of 118.8 kW (roughly the same peak heat release rate as combustion of a small trash can).

Important: Rapid transition from growth to decay stage is dependent on ventilation being limited to normal building air exchange with the door and windows in the compartment remaining closed and intact. Should the door be open, windows fail, or a combination of both, the fire may become ventilation limited, but continue in the growth stage and potentially transition through flashover to a fully developed fire.

Limitations on Fire Development in Multiple Compartment

Examination of fire development in a single, closed compartment provides a simple illustration of how compartment fire development is influenced by compartment volume and normal building ventilation. However, firefighters most commonly encounter fires in buildings comprised of multiple, interconnected compartments. Interior doors (particularly in residential occupancies) are frequently open, providing additional atmospheric oxygen for fire development and a pathway for smoke and fire travel from the compartment of origin into adjacent compartments.

In order to assess the potential for development of a ventilation limited, decay stage fire in the residential structures used in the UL experiments on the Impact of Ventilation on Fire Behavior in Legacy and Contemporary Residential Construction, researchers conducted a series of heat release rate experiment using a 5.49 m x 3.96 m x 2.44 m (18’ x 13’ x 8’) compartment, similar to the living rooms in the experimental houses. The opening in the front of the room was 3.66 m x 2.13 m (12’ x 7’) simulating the interconnection between the living room and other areas of the experimental houses.

During the HRR experiment, 3647.01 MJ of thermal energy was released over the 19 minute experiment with 2268.44 MJ released in the first 10 minutes after ignition. The total atmospheric oxygen in the single-story legacy dwelling was sufficient to support release of 846.2 MJ of thermal energy if it was completely consumed. If, as in our single compartment example, the fire becomes ventilation limited at an oxygen concentration of 10.5%, a fire in this dwelling would become ventilation limited after a release of just over 423 MJ of thermal energy. To put this in perspective in relation to HRR, in the UL living room fuel package tests, HRR reached 1 MW within 4 minutes 30 seconds and 10 MW in 5 minutes 30 seconds (Kerber, 2011).

The full-scale burns in the single-story, legacy dwelling in Experiments 1 and 3 in UL’s research provide a graphic example of the influence of ventilation on fire behavior fire development and burning regime. Experiments 1 and 3 were conducted in the one-story 111.48 m2 (1200 ft2) ranch house (see Figure 6). While the floor plan was of legacy design, the dwelling was furnished with contemporary contents including furnishings, carpet, and carpet pad.

Figure 6. Configuration of the Single Story Legacy Dwelling

In each of the experiments conducted in this structure the fire was located in the Living Room. The only major variable was the location, sequence, and total area of horizontal ventilation openings provided. There was also variation in water application method (straight versus fog stream), but this was not the primary research focus.

The living room was furnished with two sofas, armoire, television, end table, coffee table, two pictures, lamp with shade, and two curtains. The floor was covered with polyurethane foam padding and polyester carpet. Additional detail on the fuel load used during these experiments (e.g., bedrooms, kitchen, and dining room) is provided in UL’ research report Impact of Ventilation on Fire Behavior in Legacy and Contemporary Residential Construction (Kerber, 2011).

All of the experiments began with the windows and exterior door closed and all of the interior doors in the same position (open with the exception of the door to Bedroom 3 which was closed during all experiments). This ventilation profile remained constant until eight minutes (8:00) into the experiment at which point tactical ventilation was initiated. This timeframe was based on three factors: time to achieve ventilation limited conditions, potential fire service response and intervention time, and potential window failure time. After ventilation, fire development was allowed to progress to flashover or perceived maximum burning rate (based on temperature readings and observation of exterior and interior conditions).

At the conclusion of each experiment, a hand held hose stream was applied through a ventilation opening for 10 seconds. Two patterns were used, a straight stream and a 30o fog pattern positioned upward 30o to 40o from horizontal (e.g., directed towards the ceiling). The purpose of this manual water application was not to extinguish the fire completely, but to control flaming combustion in the upper layer and determine the impact of this type of water application on conditions in adjacent rooms. After manual water application with the hoseline, sprinklers were manually activated to complete the extinguishment process.

Experiment 1: This experiment was designed to simulate firefighters making entry through the front door by opening the front door eight minutes after ignition. No other ventilation openings were made in the time between opening the door and manual fire suppression with a hoseline. After manual fire suppression, the right half of the window in the living room (fire compartment) was opened.

Figure 7 illustrates the temperature and oxygen concentration at 1.24 (5’) meters above the floor throughout Experiment 1. What can be learned by examining the relationship between the temperature and oxygen concentration?

Figure 7. Experiment 1: Oxygen Concentration and Temperature at 1.24 m (5’)

As illustrated in Figure 7, it is apparent that the fire became ventilation controlled at approximately 325 seconds as oxygen concentration decreased to below 15%. However, understanding what happened next requires some thought. As previously illustrated in Figure 3, the concentration of oxygen required to support flaming combustion is dependent on temperature. The higher the temperature, the less oxygen that is required for flaming combustion. Limited ventilation can result in the fire progression into the decay stage, as it did in Experiment 1 prior to opening of the door on Side A (see Figure 6). However, increased ventilation and transition through flashover to a fully developed fire, results in burning that is still ventilation limited, as evidenced by oxygen concentrations that do not exceed 13% throughout the remainder of the experiment. The implications of a ventilation limited, but fully developed fire are a rapid, further increase in HRR (and temperature) if additional ventilation is provided. This is illustrated by the rapid temperature rise and significantly higher temperature following opening of the left half of the living room window (see Figure 7)

Experiment 3: This experiment was designed to simulate firefighters making entry through the front door and having a ventilation opening made shortly after near the seat of the fire. In this experiment the front door was opened eight minutes after ignition and the living room window was opened 15 seconds later. At the conclusion of the experiment, water from a hoseline was applied through the living room window for 10 seconds prior to manual activation of the sprinkler system.

Figure 8 illustrates the temperature and oxygen concentration at 1.24 (5’) meters above the floor throughout Experiment 3. In what ways is this similar to the relationship of oxygen concentration and temperature in Experiment 1? In what ways is it different? What can be learned by comparing the results of these two experiments?

Figure 8. Experiment 3: Oxygen Concentration and Temperature at 1.24 m (5’)

Tactical Considerations

The UL research report, Impact of Ventilation on Fire Behavior in Legacy and Contemporary Residential Construction (Kerber, 2011) identifies stages of fire development as an important tactical consideration. The following key points, expand on this important tactical consideration.

  • Fires that have progressed beyond the incipient stage are likely to be ventilation controlled when the fire department arrives.
  • Ventilation controlled fires may be in the growth, decay, or fully developed stage.
  • Regardless of the stage of fire development, when a fire is ventilation controlled, increased ventilation will always result in increased HRR.
  • Firefighters and fire officers must recognize that the ventilation profile can change (e.g., increasing ventilation) as a result of tactical action or fire effects on the building (e.g., window failure).
  • Firefighters and fire officers must anticipate potential changes in fire behavior related to changes in the ventilation profile and ensure that fire attack and ventilation are closely coordinated.

These key points do not mean that (planned, systematic, and coordinated) tactical ventilation is inappropriate. Simply that firefighters and fire officers must recognize the potential for a rapid increase in HRR when additional atmospheric oxygen is provided to ventilation controlled fires. This necessitates anticipating unplanned ventilation as a result of fire effects and close coordination of fire attack and tactical ventilation operations.

This is the foundation for many of the other tactical considerations identified in the UL’s on-line training program and research report, Impact of Ventilation on Fire Behavior in Legacy and Contemporary Residential Construction (Kerber, 2011).

Making Entry is Ventilation

Any opening that introduces air or allows smoke to escape is a ventilation opening! Often, the most significant ventilation opening during initial operations is the door through which firefighters make entry. The next post in this series will examine tactical consideration of the entry point as a ventilation opening.

References

Bukowski, R. (1985) Evaluation of furniture fire hazard using a hazard assessment computer model. Retrieved February 4, 2011 from http://fire.nist.gov/bfrlpubs/fire85/PDF/f85007.pdf.

Bukowski, R. (2006). Determining Design Fires for Design-level and Extreme Events. Retrieved February 4, 2011 from http://www.fire.nist.gov/bfrlpubs/fire06/PDF/f06014.pdf

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

McGrattan, K., Hostikka, S., Floyd, J., Baum, H., & Rehm, R. (2008). Fire dynamics simulator (Version 5) technical reference guide. Retrieved January 23, 2011 from http://www.fire.nist.gov/bfrlpubs/fire07/PDF/f07048.pdf

Society of Fire Protection Engineers (SFPE). (2002). The SFPE handbook of fire protection engineering. Quincy, MA: National Fire Protection Association.

The Engineering Toolbox (n.d.). Air exchange rates for typical rooms and buildings. Retrieved January 23, 2011 from http://www.engineeringtoolbox.com/air-change-rate-room-d_867.html

Five Days of Progress!

Sunday, May 23rd, 2010

Last night I returned from The International Fire Instructors Workshop and OTTAWA FIRE 2010 Symposium. The workshop was started in 2008 by Dr. Stefan Svensson of the Swedish Civil Contingency Agency who wanted to see what would happen if he put a number of operational fire officers, instructors, scientists and engineers, in a room together for discussion of ideas of mutual interest. Since then, the workshop has continued to provide a forum for a loosely organized network of operational firefighters and fire officers, engineers, and scientists with a passionate interest in fire dynamics and firefighting. However, despite the looseness of our organization, we have had a tremendous impact on one another and continue efforts to positively influence our respective fire services understanding of fire dynamics.

OTTAWA FIRE 2010

At the closing of OTTAWA FIRE 2010 symposium, our host, and symposium organizer, Captain Peter McBride of Ottawa Fire Services rephrased the oft repeated sentiment that the fire service has seen 100 (or more) years of tradition, unimpeded by progress. He stated that the symposium was five days of progress, unimpeded by tradition. As stated on the symposium web site:

The OTTAWA FIRE 2010 symposium was conceived to address the needs of Ottawa Fire Services personnel in response to the recommendations of the Workers’ Report on Critical Injuries as a result of the Forward Avenue Fire on February 12, 2007.

Over the last week, the Ottawa Professional Firefighters Association in partnership with the Ottawa Fire Services, the National Research Council of Canada and Carleton University’s Industrial Chair in Fire Safety Engineering hosted this international symposium which was held in Ottawa at Carleton University. The partners sought to examine the issues facing the fire service through relationships, education, discovery and advocacy. This effort was a rousing success!

Purposeful Action

Firefighter Carissa Campbell-Darmody opened the symposium with a presentation entitled First One Out, giving a first person account of her traumatic experience in the Forward Avenue fire. On February 12, 2007 the members of Ottawa Fire Services Station 11, D Platoon (Pumps 11A, 11B, and Ladder 11) responded to a reported structure fire at 187 Forward Avenue. Within 9 minutes, they would be fighting to survive wind driven rapid fire progression that cut off their means of escape from the third floor of an apartment building.

forward_ave_side_a

Note: Photo by Jean Ladonde from Workers Report Critical Injuries: Forward Avenue Fire Ottawa Fire Services Incident # 07-8038, February 2007.

Three members of Pump 11B (Lieutenant John Chatterton, Firefighter Robert Witham and Probationary Firefighter Carissa Campbell) were trapped on the third floor of Exposure Delta while conducting primary search. Two members of Ladder 11 (Lieutenant Tim Taylor and Firefighter Gerald Barrett) were trapped on the third floor of the fire unit after rescuing an occupant and continuing primary search operations. All of these members were forced to jump from the third floor (fourthlevel including basement which was substantively above grade) to escape untenable conditions and suffered burns and musculoskeletal trauma.

As with most investigations into significant injuries or fatalities, the Workers’ Investigation conducted by the Ottawa Professional Firefighters Association identified multiple causal and contributing factors related to the tragic outcome of this incident.

Carissa’s presentation of the sequence of events and the experiences of her crew during this incident were incredibly detailed, insightful, and provided a powerful focus for the purpose of the symposium.

Connections

The symposium included a wide range of presentations focused on the importance of science and engineering to the firefighters’ work. Of particular significance were discussion of Managing the Mayday by Battalion Chief George Healy of the Fire Department of the City of New York (FDNY), Understanding the Fire Environment and Ventilating Today’s Residential House Fires by Steve Kerber from Underwriters Laboratories (UL), Wind Driven Fires by Dan Madryzkowski from the National Institute for Standards and Technology (NIST) and a historical look at the evolution of Ventilation Tactics by Battalion Chief Gerry Tracy of FDNY (retired).

Symposium participants also had the opportunity to observe how scientific research impacts the fire service with a visit to the Canadian National Research Council’s fire research facility.

full_scale_test

Quantitative and Qualitative Research

On the last day of the symposium, I delivered a presentation on the use of case studies which emphasized the importance of both quantitative and qualitative research to the fire service. As frequent readers of this blog are aware, case studies can be a useful method of gaining insight into both the events involved in a particular event as well as identifying commonality with similar events. This presentation will be incorporated into several subsequent posts.

Ed Hartin, MS, EFO, MIFireE, CFO

References

Ottawa Professional Firefighters Association, International Association of Firefighters Local 162. (2007). Workers Report Critical Injuries: Forward Avenue Fire Ottawa Fire Services Incident # 07-8038, February 2007. Retrieved May 23, 2010 from http://www.ottawafirefighters.org/ottawafire2010/docs/ForwardAvenue_24_01_10.pdf

Last night I returned from The International Fire Instructors Workshop and OTTAWA F�I�R�E� 2010 Symposium. The workshop was started in 2010 by Dr. Stefan Svensson of the Swedish Civil Contingency Agency who wanted to see what would happen if he put a number of operational fire officers, instructors, scientists and engineers, in a room together for discussion of ideas of mutual interest. Since then, the workshop has been continued to provide a forum for a loosely organized network of operational firefighters and fire officers, engineers, and scientists with a passionate interest in fire dynamics and firefighting. However, despite the looseness of our organization, we have had a tremendous impact on one another and continue efforts to positively influence our respective fire services understanding of fire dynamics.

OTTAWA F�I�R�E� 2010

At the closing of OTTAWA F�I�R�E� 2010 symposium, our host, and symposium organizer, Captain Peter McBride of Ottawa Fire Services rephrased the oft repeated sentiment that the fire service has seen �100 (or more) years of tradition, unimpeded by progress�. He stated that the symposium was �five days of progress, unimpeded by tradition�. As stated on the symposium web site:

The OTTAWA F�I�R�E� 2010 symposium was conceived to address the needs of Ottawa Fire Services personnel in response to the recommendations of the Workers� Report [http://www.ottawafirefighters.org/ottawafire2010/docs/ForwardAvenue_24_01_10.pdf ] on Critical Injuries as a result of the Forward Avenue Fire on February 12, 2007.

Over the last week, the Ottawa Professional Firefighters Association in partnership with the Ottawa Fire Services, the National Research Council of Canada and Carleton University�s Industrial Chair in Fire Safety Engineering hosted this international symposium which was held in Ottawa at Carleton University. The partners sought to examine the issues facing the fire service through relationships, education, discovery and advocacy. This effort was a rousing success!

Purposeful Action

Firefighter Carissa Campbell-Darmody opened the symposium with a presentation entitled First One Out, giving a first person account of her traumatic experience in the Forward Avenue fire. On February 12, 2007 the members of Ottawa Fire Services Station 11, D Platoon (Pumps 11A, 11B, and Ladder 11) responded to a reported structure fire at 187 Forward Avenue. Within 9 minutes, they would be fighting to survive wind driven rapid fire progression that cut off their means of escape from the third floor of an apartment building.

forward_ave_side_a.jpg

Note: Photo by Jean Ladonde from Workers Report Critical Injuries: Forward Avenue Fire Ottawa Fire Services Incident # 07-8038, February 2007.

Three members of Pump 11B (Lieutenant John Chatterton, Firefighter Robert Witham, Probationary Firefighter Carissa Campbell) were trapped on the third floor of Exposure Delta while conducting primary search. Two members of Ladder 11 (Lieutenant Tim Taylor, Firefighter Gerald Barrett) were trapped on the third floor of the fire unit after rescuing an occupant and continuing primary search operations. All of these members were forced to jump from the third floor (forth level including basement which was substantively above grade) to escape untenable conditions and suffered burns and musculoskeletal trauma.

As with most investigations into significant injuries or fatalities, the Workers Investigation conducted by the Ottawa Professional Firefighters identified multiple causal and contributing factors related to the tragic outcome of this incident.

Carissa�s presentation of the sequence of events and the experiences of her crew during this incident were incredibly detailed, insightful, and provided a powerful focus for the purpose of the symposium.

Connections

The symposium included a wide range of presentations focused on the importance of science and engineering to the firefighters work. Of particular significance were discussion of Managing the Mayday by Battalion Chief George Healy of the Fire Department of the City of New York (FDNY), Understanding the Fire Environment and Ventilating Today�s Residential House Fires by Steve Kerber from Underwriters Laboratories (UL), Wind Driven Fires by Dan Madryzkowski from the National Institute for Standards and Technology (NIST) and a historical look at the evolution of Ventilation Tactics by Battalion Chief Gerry Tracy of FDNY (retired).

Symposium participants also had the opportunity to observe how scientific research impacts the fire service with a visit to the Canadian National Research Council�s fire research facility.

full_scale_test.jpg

Quantitative and Qualitative Research

On Friday, I delivered a presentation on the use of case studies which emphasized the importance of both quantitative and qualitative research to the fire service. As frequent readers of this blog are aware, case studies can be a useful method of gaining insight into both the events involved in a particular event as well as identifying commonality with similar events. This presentation will be incorporated into several subsequent posts.

Ed Hartin, MS, EFO, MIFireE, CFO

References

Ottawa Professional Firefighters Association, International Association of Firefighters Local 162. (2007). Workers Report Critical Injuries: Forward Avenue Fire Ottawa Fire Services Incident # 07-8038, February 2007. Retrieved May 23, 2010 from http://www.ottawafirefighters.org/ottawafire2010/docs/ForwardAvenue_24_01_10.pdf

Reading the Fire 11

Thursday, November 5th, 2009

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 an apartment fire.

Apartment Fire

The Alexandria, VA fire department was dispatched to an apartment fire at the Parkfairfax Complex in the 3700 block of Lyons Lane. First arriving companies observed a large volume of smoke from the attic of a four unit, townhouse style condominium building.

Download and the B-SAHF Worksheet.

Video Segment 1 is shot from Side A, towards the A/D corner. Watch the first 2 minutes of this video clip. First, describe what you observe in terms of the Building, Smoke, Air Track, Heat, and Flame Indicators; 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 (on floor 2 and in the attic)?
  5. How would you expect the fire to develop over the next two to three minutes

Watch the remainder of Video Segment 1 and identify if, and how conditions change from the beginning of the clip.

  1. Did fire conditions progress as you anticipated?
  2. What influence did the failure of the roof sheathing over the unit on Side B have on fire conditions in the attic?
  3. What concerns would you have about working on the top floor of the unit on Side B (and possibly Exposure D1)?

Video Segments 2-5 illustrate fire conditions from several different perspectives and show fire development and the impact of tactical operations as the incident progresses. Note: These video clips will open in a new window.

While this incident had a positive outcome, it is important to recognize the potential for collapse of lightweight, engineered structural systems such as truss roof assemblies. Tactical success in one incident is not necessarily a predictor of future success should conditions be different (e.g., duration of fire impingement on structural members prior to arrival, burning regime, changes to the ventilation profile, etc.).

Master Your Craft

Ed Hartin, MS, EFO, MIFIreE, CFO

CFBT Seminar-MSB Sand

Sunday, October 18th, 2009

On 12-16 October 2009 a group of compartment fire behavior training (CFBT) instructors representing six nations gathered for a seminar at the Myndigheten fr Samhllsskydd och Beredskap (MSB) (Swedish Civil Contingencies Agency) College in Sand, Sweden. This was a unique event in that the group had the opportunity to learn the history of Swedish fire behavior training from Mats Rosander, Marcos Dominquez, and Nils Bergstrm, three pioneers in fire control methods and training.

Figure 1. Mats Rosander and Nils Bergstrm

history_09

(Left to Right) Mats Rosander, Ed Hartin, & Nils Bergstrm

In addition to presentations on the history and evolution of Swedish fire behavior training and fire control methods, workshop participants participated in representative examples of fire behavior classroom instruction laboratory exercises and practical evolutions conducted at Sand.

Figure 2. Practical Exercises

practical

The MSB College at Sand has extensive live fire training facilities with demonstration, attack, window, and large volume cells as well as a variety of multi-compartment live fire training props.

Figure 3. Mats, Marcos, & Nisse Preparing the Aquarium

aquarium

Figure 3. Backdraft Demonstration in the Classroom

aquarium2

Seminar Presentations

On Thursday morning, Shan Raffel, Peter McBride, John McDonough, and Ed Hartin delivered short presentations on Reading the Fire, Role of the Incident Safety Officer, Firefighter Behavior (transfer of training to incident operations), and Live Fire Training as Simulation: The Role of Fidelity in Effective Training. This segment of the workshop was open to college staff, students attending courses at the college, and local fire service personnel.

Figure 4. Seminar Presentation

ed_presentation

Download Live Fire Training as Simulation: The Role of Fidelity in Effective Training.

So What?

Seminar participants all recognized this seminar as an extremely significant event. On the surface, it appears to be an ordinary seminar, but in reality it was really quite different. Great strides have been made in developing relationships between compartment fire behavior training practitioners around the world through the Institution of Fire Engineers (IFE) Compartment Firefighting Special Interest Group (SIG) International Fire Instructors Workshops held in Revenge, Sweden (2008) and Sydney, Australia (2009). However, this event was unique in that it provided a bridge back into history. Unfortunately, leaders and pioneers in many fields are not recognized during their lifetime, limiting researchers and students to often meager written records of their contributions. This workshop provided the participants with the opportunity to make a direct connection to the origins of many innovative concepts and developments in fire behavior and fire control theory.

Fire Behavior Pioneers Honored

Yesterday morning, Acting Inspector Shan Raffel, ASFM, CMIFireE, EngTec, presented certificates of recognition to Mats Rosander, Nils Bergstrm, Marcos Dominguez, and Krister Giselsson (posthumously) on behalf of the Institution IFE and fire services around the world for their pioneering work in fire behavior training and firefighting operations.

Special Thanks

I would like to acknowledge the efforts of Roy Reyes, his colleague David Flateb, and the staff of the MSB College at Sand in facilitating this important seminar. This was an important step in forging a stronger network of fire service leaders committed to ensuring that firefighters have the knowledge and skills necessary to operate safely and effectively in an ever changing built environment.

Whats Next?

It will take some time to digest the tremendous amount of information from the Sand Workshop. However, I look forward to sharing what I have learned and providing a bit of historical context for much of what we are doing in fire behavior training today.

My next post will return to examination of fire behavior indicators related to fires in the fully developed stage along with variations in conditions when fire conditions impact on multiple compartments (as is usually the case).

Ed Hartin, MS, EFO, MIFireE, CFO

Upcoming Events and Information

Monday, October 12th, 2009

Open Enrollment CFBT Level I & Instructor Courses

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

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

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

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

CFBT Workshop in Sand, Sweden

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

Figure 1. Fire Behavior Training in Sand

sando1

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

Figure 2. MSB College in Sand

sando2

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

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

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

NIOSH Death in the Line of Duty F2007-02

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

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

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

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

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

Ed Hartin, MS, EFO, MIFireE, CFO

Compartment Fire Behavior Blog Anniversary!

Monday, August 10th, 2009

Just over a year ago I had the idea to develop a blog focused on compartment fire behavior and firefighting. A bit of work on the technology side and I made my introductory post on 8 August 2008. That month the CFBT-US web site had 2900 page views, this past July the page view count was in excess of 24,000 with 4400 unique readers. While this is not a huge readership in terms of the total number of firefighters in the world who have English as a language, it shows significant growth.

Accomplishments

At the start of this adventure, I set a goal to post twice weekly (Monday and Thursday mornings) and for the most part have managed to keep this schedule. Dominant themes have included:

  • Reviews of books, training programs, magazine/journal articles, and conference presentations
  • Case studies based on National Institute for Occupational Safety and Health (NIOSH) and agency reports on significant incidents, injuries, and fatalities
  • An ongoing series of posts examining the B-SAHF (building, smoke, air track, heat, and flame) organizing scheme for fire behavior indicators and reading the fire
  • B-SAHF video and photo based exercises in reading and interpreting B-SAHF indicators to predict likely fire behavior and the impact of tactical operations
  • Examination of extreme fire behavior phenomena such as flashover, backdraft, smoke explosion, and flash fire with an emphasis on understanding the underlying causes and influence of tactical operations on fire dynamics
  • Discussion of research on positive pressure ventilation and wind driven fires conducted by the National Institute for Standards and Technology
  • Identification of the potential learning opportunity presented by systematic investigation of near miss, injury, and fatality incidents
  • Discussion of the importance of deliberate practice and the concept of the need for 10,000 hours to master your craft

Hopefully you have found these posts useful in developing your understanding of compartment fire behavior or have motivated you to take action and share your knowledge of our profession with others. I have benefited greatly from the thought process and effort of writing on a regular and systematic basis.

As a reference, I have prepared a printer friendly Compartment Fire Behavior Blog Index in portable document format (PDF) which includes the date, title, URL, and brief synopsis of post content.

I Need Your Help

Your comments and feedback are important to making the Compartment Fire Behavior Blog better. If I write something that you do not agree with or think that a concept could be expressed more clearly, please comment or question!

The Way Forward

I am currently working on a loose editorial calendar to help guide my writing over the next year. Several important themes will continue:

  • Case studies and lessons learned
  • Reading the fire and B-SAHF exercises
  • Practical fire dynamics
  • Review of books, magazine/journal articles
  • Fire control and tactical ventilation

If there are topics you think should be on the list, please provide your input as a comment on this post.

My next several posts will get back to study of the B-SAHF scheme with a look at Heat Indicators and continuing examination of flashover. As I have been looking back over the last year, I find that I have taken two distinctly different approaches to sequencing posts. Some topics have been addressed in successive posts (e.g., case studies and discussion of wind driven fires) and others have alternated between several different topics (e.g., B-SAHF and flashover). From my perspective, each has its advantages and disadvantages. If you have a preference or opinion, please let me know!

Thanks for your readership and participation,

Ed Hartin, MS, EFO, MIFireE, CFO