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Most of the provisions outlined in National Fire Protection Association (NFPA) 1403 Standard on Live Fire Training Evolutions, deal with mitigating the risk of traumatic injury or fatality. The standard addresses training prerequisites, but does not speak to medical and physical capacity prerequisites. The standard does specify that:

• The instructor-in-charge is responsible for provision of rest, and rehabilitation (inclusive of medical evaluation)
• Emergency medical services must be available on-site, and
• The instructor-in-charge is responsible for overall fireground activiey to ensure correct [emphasis added] levels of safety.

While the emphasis on live fire training safety has been placed on traumatic injuries and fatalities, this is not the predominant cause of live fire training line of duty deaths. Between 1994 and 2003, 65% of live fire training related fatalities resulted from physiological stress and heart attack (Grimwood, Hartin, McDonough, & Raffel, 2005)

NIOSH recently released Death in the Line of Duty Reports 2008-30 and 2008-36, both of which examined incidents in which firefighters lost their lives during or immediately after live fire training. It is easy to glance at these reports and think that this is just another heart attack with the same recommendations as all the other report. However, I encourage you to stop, read these two reports, and give some thought to what this information means to you on a personal level.

NIOSH Report 2008-30

On August 9, 2008; Captain Sean Whiten (Age 47) was leading a team of students during live fire training in a purpose built burn building. After completing an interior attack, Captain Whiten complained of being tired but otherwise had no complaints. Medical evaluation conducted as part of the rehabilitation process showed elevated pulse and blood pressure, but this was consistent with participation in a strenuous training activity.

After rehab, Captain Whiten was relaxing by his vehicle when he went into cardiac arrest. Instructors and students began CPR and applied a automatic external defibrillator prior to the arrival of an advanced life support ambulance. Paramedics initiated advanced live support procedures and transported Captain Whiten to the hospital where resuscitation efforts continued until he was pronounced dead by the attending physician.

An autopsy conducted by a forensic pathologist discovered that Captain Whiten suffered from coronary artery disease and had ventricular hypertrophy (LVH) and cardiomegaly, conditions which increase the risk of sudden cardiac death. The Captain also had mild elevation of his carboxyhemoglobin (COHb) level, but it is unclear if this had any influence on his heart attack and sudden cardiac death. The Captain’s risk factors for CAD included male gender, age over 45, high blood cholesterol, and obesity. However, he had been cleared by his primary care physician to engage in a fire department physical ability test.

NIOSH Report 2008-36

On July 6, 2008 Firefighter Rufus Brinson (Age 50) was teaching a class involving live fire training at a local community college. After several evolutions under high ambient temperature 34.4^o C (94^o F) and high relative humidity (58%), including a search drill conducted using hot smoke in a purpose built burn building, Firefighter Brinson indicated that he was not feeling well and took a break in the air conditioned cab of the engine. Another instructor took over teaching for the next evolution while Firefighter Brinson operated the pump. While refilling the apparatus tank after the final evolution, he collapsed next to the apparatus.

An instructor initiated CPR and requested an ambulance. The ambulance was staffed with intermediate level emergency medical technicians who requested response of a paramedic level unit. Transport was initiated prior to the arrival of paramedics who met the ambulance enroute to the hospital and initiated advanced life support procedures. Resuscitation efforts continued at the hospital until Firefighter Brinson was pronounced dead by the attending physician.

An autopsy conducted by the medical examiner listed congestive heart failure as the cause of death and severe coronary atherosclerotic disease and hypertensive heart disease as contributing factors. Firefighter Brinson was also found to have left ventricular hypertrophy (LVH) and cardiomegaly. Risk factors for CAD included male gender, age over 45, smoking, overweight (but not obese), and limited aerobic exercise. Firefighter Brinson had not had a medical exam by a physician in seven years.

Common NIOSH Recommendations

While both of these reports contains unique recommendations based on the circumstances involved, there are also several common recommendations:

Provide pre-placement and annual medical evaluations to fire fighters consistent with National Fire Protection As­sociation (NFPA) 1582, Standard on Comprehensive Occupational Medical Program for Fire Departments, to determine their medical ability to perform duties without presenting a significant risk to the safety and health of themselves or others.

Incorporate exercise stress tests following standard medical guidelines into a Fire Department medical evaluation program.

Ensure fire fighters are cleared for return to duty by a physician knowledge­able about the physical demands of fire fighting, the personal protective equipment used by fire fighters, and the vari­ous components of NFPA 1582.

Phase in a comprehensive wellness and fitness program for fire fighters to reduce risk factors for cardiovascular disease and improve cardiovascular capacity.

Perform an annual physical performance (physical ability) evaluation to ensure fire fighters are physically capable of performing the essential job tasks of structural fire fighting.

Provide fire fighters with medical clearance to wear a self-contained breathing apparatus (SCBA) as part of a Fire Department medical evaluation program.

These recommendations are no surprise. It is commonly known that firefighting is a physiologically stressful activity and that working in a high ambient temperature environment increases that stress substantially. Firefighters must be well and fit in order to safely and effectively operate in realistic training and on the fireground.

Responsibility

Who is responsible for ensuring that firefighters are medically and physically capable of engaging in firefighting operations? On one hand, you can make a reasonable argument that it is the fire department’s (employer’s) responsibility. One of the foundations of occupational safety and health regulation is the employer’s responsibility to provide a place of employment which is free from recognized hazards that are causing or likely to cause death or serious physical harm. However, is this solely the employer’s responsibility?

In examining this issue, I will put things in a personal context. I am a male, over 50, have a family history of heart disease, and last ago was diagnosed with hyperlipidemia (high cholesterol). While not grossly overweight, over the last 10 or 12 years my body mass index had crept up and outside the optimum. In addition, my work schedule and graduate studies had negatively impacted my workout schedule and reduced my aerobic exercise considerably. When I had my annual medical physical as a hazmat technician, the occupational medicine physician indicated that I should talk with my primary care physician about my cholesterol level lose some weight, and get more aerobic exercise. Several weeks later, I sat with my dad (a retired fire chief) as he died from congestive heart failure (at age 92). He had retired due to a heart attack the year I started my fire service career. The time that I spent with him over the last week of his life gave me a great deal to think about.

While my employer should (and does) provide medical physicals, respirator qualification, physical ability assessment, and the facilities and time to work out, I am the one responsible for action. Since last summer, I have lost 15.9 kg (35 pounds), substantially improved my aerobic fitness, and reduced my cholesterol to near optimal level. While I had not noticed the degradation in my physical capacity (other than to figure that I was getting old), I have noticed a significant improvement. I feel better on a day-to-day basis and find myself less fatigued when delivering live fire training.

Fire service organizations have a responsibility to their members to provide medical/physical assessment and wellness/fitness programs. However, each of us also has a responsibility to ensure that we are medically and physically qualified for the work we are doing. Take care of yourself and look out for the people you work with!

References

National Fire Protection Association (NFPA). (2007). Standard on live fire training evolutions. Quincy, MA: Author.

National Institute for Occupational Safety and Health (NIOSH). (2008). Death in the line of duty (Report Number 2008-30). Retrieved June 4, 2009, from http://www.cdc.gov/niosh/fire/pdfs/face200830.pdf

National Institute for Occupational Safety and Health (NIOSH). (2008). Death in the line of duty (Report Number 2008-36). Retrieved June 4, 2009, from http://www.cdc.gov/niosh/fire/pdfs/face200836.pdf

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

Art and Science of Firefighting

NIST has performed a wide range of research that can have a positive impact on the safety and effectiveness of firefighting operations. However, all too often, this information has not made it to front line firefighters. Dan Madrzykowski and Steve Kerber have made a concerted effort to address this issue and increase the day to day impact of NIST fire research. In the video overview of the wind driven fire research, Battalion Chief Jerry Tracy of the FDNY stated that this project was an effort to bridge the gap between the science and art of firefighting and get science to the street.

Research on Wind Driven Fires= Governors Island, New York City

Note: John Freeman Photo from NIST Report TN 1629

Understanding, Surviving, & Fighting Wind Driven Fires

This two DVD training package is based on NIST research conducted at the Building Fire Research Lab (BFRL) in Gaithersburg, MD and on Governors Island in New York city. The package contains:

• Written reports on the laboratory and field experiments
• Multiple videos of the experiments (from standard and thermal imaging video cameras)
• PowerPoint presentation on experimental procedures and results
• Video overview of the research and implications for fireground operations

While the reports and detailed video are tremendous resources, I believe that every firefighter in the United States would benefit from taking 86 minutes to watch the introductory video overview narrated by Battalion Chiefs Peter Van Dorpe (Chicago Fire Department), Jerry Tracy (Fire Department of New York), Dan Madrzykowski (NIST), and Steve Kerber (NIST). The overview presentation is divided into four segments:

1. Introduction and the Chicago Fire Department Experience (BC Peter Van Dorpe)
2. The FDNY Experience (BC Jerry Tracy)
3. Laboratory Experiments (Dan Madrzykowski, PE)
4. Governors Island Experiments (Steve Kerber)
5. Conclusion (BCs Peter Van Dorpe and Jerry Tracy)

This video provides a powerful explanation of the potential danger of wind driven fires (in both high and low-rise structures) and illustrates how scientific research can have a positive impact on the safety and effectiveness of fireground operations. While some may discount the information presented because the research focused (to a large extent) on high-rise buildings, many of the lessons learned have applicability to a much wider range of buildings.

In the summary section of the overview video, BC Peter Van Dorpe made several interesting observations regarding the lessons he learned from this research:

In a high-rise building, you don’t ventilate until you have water on the fire based on potential for a wind driven fire and dramatic influence of wind and ventilation on fire behavior.

Consideration of the concept that the first water on a high-rise fire [in a non-sprinklered building] should be from the exterior based on the dramatic effect of relatively low flow application from the exterior in changing conditions from severe to controllable.

BC Jerry Tracy emphasized the importance of integrating the art and science of firefighting and the need for change. Credibility is critical, both from a scientific and operational perspective. He pointed to the importance of understanding impact of changes in ventilation profile on fire behavior in all types of fires and the potential benefits of alternative strategies and tactics.

How to Order

This two DVD set can be ordered from the United States Fire Administration (USFA) Web Site. However, orders are limited to a single set per organization.

Order Evaluating Firefighting Tactics Under Wind Driven Conditions

Information on this research is also available on the NIST Wind Driven Fire Research web page.

Action Steps

Get a copy of this training package and have a look at the overview video. Ask yourself how this information can be put to work in your environment? What application does this research have beyond high-rise buildings? How can we use this information to increase the safety and effectiveness of firefighting operations in single and multi-family dwellings and in commercial buildings?

CFBT-US on Twitter

In an effort to expand our network, CFBT-US is now on Twitter! Follow Chief Instructor Ed Hartin for information on fire behavior, incident information, photos and video for B-SAHF exercises. Check out the Twitter Portal for an overview video on Twitter and additional information on this social networking tool.

CFBT-US is exploring how to integrate Twitter with the CFBT Blog (and the blog with Twitter). Please share your feedback on the effectiveness and utility of this approach to information sharing.

Ed Hartin, MS, EFO, MIFireE, CFO

Application of the B-SAHF (Building, Smoke, Air Track, Heat, & Flame) organizing scheme for critical fire behavior indicators to photographs or video of structure fires provides an excellent opportunity to develop your knowledge of fire behavior and skill in reading the fire.

Residential Fire

Shortly after 1730 hours on May 19, 2008, companies from the Baltimore City Fire Department were dispatched for a residential fire at 321 S Calhoun Street. Responding companies observed a large column of smoke from several blocks away.

Download and print the B-SAHF Worksheet. Watch the first 60 seconds of the video clip. 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?

1. Watch the next 60 seconds (first two minutes) of the video clip and consider the following questions:
2. What changes in fire behavior indicators have you observed in the second 60 seconds?

Watch the remainder of the video and see if your assessment matches actual incident conditions. Additional video of this incident can be viewed on the WBAL-TV { http://www.wbaltv.com/video/19514614/index.html ] web site.

Remember the Past

As mentioned in earlier posts, I am involved in an ongoing project to assemble and examine narratives, incident reports, and investigations related to extreme fire behavior events. Unfortunately many of these documents relate to line of duty deaths. As I read through the narratives included in the United States Fire Administration line of duty death database and annual reports on firefighter fatalities, I realized that every week represents the anniversary of the death of one or more firefighters as a result of extreme fire behavior.

While some firefighters have heard about the incidents involving multiple fatalities, others have not and most do not know the stories of firefighters who died alone. In an effort to encourage us to remember the lessons of the past and continue our study of fire behavior, I will occasionally be including brief narratives and links to NIOSH Death in the Line of Duty reports and other documentation in my posts.

May 30, 1999
Firefighter Lewis Jefferson Matthews
Firefighter Anthony Sean Phillips, Sr.
District of Columbia Fire Department

District of Columbia Fire Department Firefighter Matthews and Firefighter Phillips were members of two different engine companies working on the first floor of a townhouse that was experiencing a fire. Both crews had entered the front door of the townhouse at street level. The fire was confined to the basement. The basement, at grade at the rear of the structure, was opened by a truck company and a small fire was observed. A company officer at the basement door requested permission to hit the fire but his request was denied by the incident commander since he knew that crews were in the building and he did not want to have an opposing hose stream situation. The fire grew rapidly and extended up the basement stairs into the living areas of the townhouse where Firefighter Matthews, Firefighter Phillips, and other firefighters were working. With the exception of Firefighter Matthews and Firefighter Phillips, all firefighters exited

the building after the progress of the fire made the living area of the townhouse untenable. On the exterior of the building, firefighters realized that Firefighter Matthews was not accounted for. Firefighters reentered the building and followed the sound of a PASS device. They removed the firefighter with the activated PASS to the exterior of the building. Once outside, firefighters realized that the firefighter who had been rescued was not Firefighter Matthews, but was, in fact, Firefighter Phillips. The search continued and Firefighter Matthews was discovered and removed approximately 4 minutes later. Firefighter Phillips’ PASS device was of the type that is automatically activated when the SCBA is activated and it worked properly. Firefighter Matthews’ PASS was a manually activated type and it was found in the “off” position. Both firefighters received immediate medical care on the scene and were transported rapidly to hospitals. Firefighter Phillips was pronounced dead upon arrival at the hospital and Firefighter Matthews died the following day, May 31, 1999. Firefighter Phillips died as the result of burns over 60 percent of his body surface area and his airway. Firefighter Matthews died as the result of burns over 90 percent of his body surface area and his airway. 2 other firefighters were injured fighting the fire. One (1) of these 2 firefighters, who suffered burns over 60 percent of his body surface area, survived and was released from the hospital in late August. At the time of his release, it was not clear if this firefighter would ever return to work. Additional information about this incident can be found in NIOSH Fire Fighter Fatality Investigation 99-F-21 and National Institute for Standards and Technology (NIST) report Simulation of the Dynamics of the Fire at 3146 Cherry Road NE, Washington D.C., May 30, 1999.

May 9, 2001
Firefighter Alberto Tirado
Passaic Fire Department, New Jersey

Firefighter Tirado and members of his department were dispatched to a report of a fire in an occupied three-story apartment building. The first-arriving engine company reported a working fire and Firefighter Tirado responded as the tiller driver of the first-arriving ladder company.

Firefighters on-scene received reports that children were trapped in the building. Firefighter Tirado and another firefighter from his company proceeded to the second floor of the building to conduct a search. A search of the second floor was conducted and all of the apartments on that floor were found to be clear. Firefighter Tirado and the other firefighter proceeded to the third floor to continue their search. On their way to the third floor, the team encountered heavy smoke and high heat. Both firefighters went back to the second-story landing. Firefighter Tirado’s partner told Firefighter Tirado to wait on the landing while he retrieved additional lighting from the apparatus.

A few minutes later, Firefighter Tirado called on the radio and said that he was trapped on the third floor. This transmission was not heard on the fireground and a second request for help was also not heard. He called a third time and reported that he was trapped on the third floor and needed help. Firefighter Tirado’s exit path had been blocked by fire, and he was unable to find his way out.

A defective throttle on the pumper supplying the initial attack line created water supply and pressure problems. Firefighters were unable to advance to the third floor to rescue Firefighter Tirado. The fire on the third floor grew to a point where it was impossible for firefighters to control it with handlines. An aerial master stream was used to darken down the fire and allow firefighters to access the third floor. After a number of attempts, Firefighter Tirado was discovered in a third-story bedroom.

The cause of death was listed as asphyxiation. Firefighter Tirado’s carboxyhemoglobin level was found to be 65%. The fire was caused by an unsupervised 12 year old girl that was attempting to light a stove. The children that were reported trapped were actually out of the building.

For additional information on this incident, refer to NIOSH Fire Fighter Fatality Investigation F2001-18.

Ed Hartin, MS, EFO, MIFireE, CFO

This post reviews articles on positive pressure ventilation written by Watch Manager Gary West of the Lancashire (UK) Fire and Rescue Service and Battalion Chief Kriss Garcia of the Salt Lake City Fire Department. Gary, Kriss, and I were recently in Australia for a meeting of the Institution of Fire Engineers (IFE) Compartment Firefighting Special Interest Group and to present at the 2009 International Firefighting Safety Conference hosted by IFE-Australia.

Gary and Kriss are both strong advocates of positive pressure ventilation (PPV) and its use to support fire attack (positive pressure attack (PPA)). In August 2008, Gary’s article Positive Thinking was published in Fire Risk Management Journal and October 2008, Kriss’s article The Power of Negative Thinking was published in FireRescue magazine. While the titles appear to be contradictory, both of my colleagues had a common theme; the importance of education and training to ensure safe and effective tactical ventilation on the fireground.

Common Elements

Gary and Kriss both emphasize the benefits of effective use of PPV while cautioning that education in practical fluid and fire dynamics and tactical ventilation concepts must be integrated with training in PPV/PPA tactics.

Positive Thinking

Gary provides an overview of the three phased approach to PPV training and implementation commonly used in the UK. This approach is designed around building understanding of key concepts and competence in tactical skills while minimizing risk.

Phase I-Post Fire Control PPV: In this phase, PPV is limited to clearing smoke after the fire has been controlled. In many respects this is the simplest and safest application of PPV.

Phase 2-Defensive PPV: In Phase 2, PPV is used during firefighting operations to clear smoke logged areas not involved in fire. This approach requires confinement of the fire using structural barriers (e.g., closing doors) and placement of hoselines. This tactical approach is less common in the United States, likely due to differences in construction. However, use of PPV to clear and then pressurize attached exposures can be an effective tactic in limiting smoke and fire spread.

Phase 3-Offensive PPV (PPA): In the third phase, PPV precedes fire attack and has a direct influence on fire behavior as well as clearing smoke from the entry path and uninvolved areas of the building.

Gary concludes with reinforcement of the importance of education and training prior to implementation and the criticality of ongoing training and development:

It must be understood that PPV is a tool that will save the lives of casualties, and also reduce the risk to firefighters, if used correctly. Initial training should cover all aspect of fan configurations, the different phases of PPV, and include an understanding of the way in which fire behaves generally [emphasis added], among other things.

However, it cannot be emphasized enough that, if used incorrectly, PPV is a potentially life-threatening and, as such, an ongoing training and development programme ought to be available to all users [emphasis added] (P. 49).

Critique of Positive Thinking

Gary provides a solid overview of the three phased approach to PPV training and implementation used in the UK and advocates for progression to Phase 3, positive pressure ventilation in support of fire attack. However, I take exception to two statements made in this article.

The first relates to the relationship between the size of inlet and exhaust opening. “It is widely understood that the size of the exhaust(s) must add up to less than the surface are of the inlet in order that positive pressure is achieved.” This is incorrect. As outlined in my previous post, Positive Pressure Ventilation: Inadequate Exhaust, the exhaust opening should be at least equal to the size of the inlet and preferably two to three times the area of the inlet opening.

The second statement relates to water application technique. “Students have a temptation to apply water using pulsing and gas-cooling techniques. However, it is not necessary in this mode of PPV [Phase 3]. While of less concern than inadequately sized exhaust openings, use of PPV does not necessarily negate the use of gas cooling. Depending on firefighters operating location and conditions encountered, cooling hot gases may still be necessary, particularly away from the path leading from inlet to outlet. Nozzle techniques and water application should be determined based on conditions, not the ventilation tactic being used. However, that said, Gary is correct that excess steam produced during attack in the fire compartment will be carried out the exhaust opening.

Negative Thinking

Kriss shares much of Gary’s perspective regarding the value of PPV and in particular its use to support fire attack (Phase 3/PPA).  However, the main focus of The Power of Negative Thinking is on the practical aspects of the fluid dynamics involved in PPV. Kris points out that the application of positive pressure at an inlet simply adds a slight amount of pressure to direct the flow of fire effluent from the inlet to the exhaust opening(s).

Kriss states that “When PPA goes wrong, it’s usually attributable to one or two conditions, or their combination. First, mistakes result from a lack of coordination and control on the fireground including a lack of department wide training and education in the use of PPA.

Second, problems may arise from insufficient or not forward exhaust. When products of combustion are emitted under pressure adhead of the attack crews, substantial exhaust is need (P. 39).

One of the most important points that Kriss raises in this article is the importance of reading conditions at the inlet opening (which he refers to as the “ventilation” opening). “If heavy smoke and/or fire is returning to the attack entrance [and] exhausting above the blower, do not enter“ (p. 39) [additional emphasis added].

This article also outlines initial considerations for using PPV in support of fire attack Phase 3/PPA). Of particular importance is training and educating members in theory, application, and precautions involved in the offensive use of PPV. In addition, departments training and implementing the use of this tactic must define when it will be used (e.g., fire conditions, building types).

Critique of Negative Thinking

This article raises important points in developing an understanding of why PPV works (e.g., pressure differences) and provides a straightforward explanation of its safe use in support of fire attack. However, Kriss indicates that the pressure generated by the blower is less than that created by the fire and expansion of steam due to fire control operations. This is inconsistent with the results of research conducted by NIST (Kerber & Madryzkowski, 2008; 2009). On a related note, Kriss’s assumptions regarding pressure generated by steam expansion are dependent on excessive or inappropriate water application during fire suppression operations (which is not necessarily a given).

Final Thoughts

In these two articles, Gary and Kriss raise a number of important points and focus attention on the importance of understanding not simply what and how, but why. Kriss’s emphasis on the importance of having a decision-making framework and assessing conditions to determine if PPV is working prior to entry is absolutely critical. Sometime in the next couple of months I will expand on the topic of command, control, and coordination of fire control and ventilation.

Ed Hartin, MS, EFO, MIFireE, CFO

References

West, G. (2008, August). Positive thinking. Fire Risk Management, 46-49.

Garcia, K. (2008, October) The power of negative thinking. Fire Rescue, 38-40. Retrieved May 24, 2009 from http://positivepressureattack.com/images/pdfs/PowerOfNegativeThinking.pdf

Kerber, S. & Madrzykowski, D. (2008).Evaluating positive pressure ventilation In large structures: school pressure and fire experiments. Retrieved May 17, 2009 from http://www.fire.nist.gov/bfrlpubs/fire08/PDF/f08016.pdf.

Madrzykowski, D. & Kerber, S. (2009). Fire Fighting Tactics Under Wind Driven Conditions. Retrieved (in four parts) February 28, 2009 from http://www.nfpa.org/assets/files//PDF/Research/Wind_Driven_Report_Part1.pdf; http://www.nfpa.org/assets/files//PDF/Research/Wind_Driven_Report_Part2.pdf; http://www.nfpa.org/assets/files//PDF/Research/Wind_Driven_Report_Part3.pdf; http://www.nfpa.org/assets/files//PDF/Research/Wind_Driven_Report_Part4.pdf.

Application of the B-SAHF (Building, Smoke, Air Track, Heat, & Flame) organizing scheme for critical fire behavior indicators to photographs or video of structure fires provides an excellent opportunity to develop your knowledge of fire behavior and skill in reading the fire.

This video clip was recommended by Captain Virgil Hall, Tualatin Valley Fire & Rescue. Virgil is stationed at Station 64 and is one of TVF&R’s CFBT Instructors.

Residential Fire

Download and print the B-SAHF Worksheet. Consider the information provided in the short 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?

Review the video again, watch the indicators on Side A closely, and give some thought to the following questions posed by Captain Hall:

1. How did the smoke and flame indicators change?
2. What did this indicate?
3. Why did these changes occur (what were the influencing factors)?

Special thanks to Captain Hall for recommending this video clip. Please feel free to contribute to this process and share or recommend video clips or photographs that will help us develop our skill in reading the fire.

Remember the Past

While some firefighters have heard about the incidents involving multiple fatalities, others have not and most do not know the stories of firefighters who died alone. In an effort to encourage us to remember the lessons of the past and continue our study of fire behavior, I will occasionally be including brief narratives and links to NIOSH Death in the Line of Duty reports and other documentation in my posts. The first narrative in this post is incomplete as this incident, resulting in the death of two members of the Houston Fire Department occured last Sunday. It is important for us to continue our efforts to understand and mitigate the complex and interrelated factors that result in firefighter fatalities occuring during structural firefighting operations.

April 12, 2009
Captain James Harlow
Firefighter Damion Hobbs
Houston Fire Department, Texas

Captain James Harlow and Firefighter Damion Hobbs of the Houston, Texas Fire Department lost their lives in the line of duty while conducting primary search in a single family dwelling on the morning of April 12, 2009. Preliminary information indicates that Captain Harlow and Firefighter Hobbs were trapped by rapid fire progress, possibly influenced by wind. The Houston Fire Department, Texas State Fire Marshal, and National Institute for Occupational Safety and Health (NIOSH) are all investigating this incident. More information will be posted as it becomes available.

April 11, 1994
Lieutenant Michael Mathis
Private William Bridges
Memphis Fire Department, Tennessee

On April 11, Lt. Michael Mathis and Private William Bridges of the Memphis (TN) Fire Department were killed when they became trapped and overcome by smoke during a fire on the ninth floor of a high rise building. Two civilians also died in the arson fire. Lt. Mathis became disoriented when he was caught in rapidly spreading fire conditions on the fire floor, burning him and causing his SCBA to malfunction. He found his way into a room on the ninth floor were he was later discovered by other fire crews with his SCBA air depleted. Private Bridges, aware that Lt. Mathis was unaccounted for after several unsuccessful attempts to contact him by radio, left a safe stairwell where he had been attempting to fix a problem with his own SCBA. Investigators believe Bridges was trying to locate Lt. Mathis. Bridges became entangled in fallen cable TV wiring within a few feet of the stairwell, and died of smoke inhalation after depleting his SCBA supply. A Memphis Fire Department investigation found many violations of standard operating procedures by companies on the scene, including crews taking the elevator to the fire floor, problems with the incident command system and coordination of companies, operating a ladder pipe with crews still on the fire floor, and a failure of personnel, including Lt. Mathis and Private Bridges, to activate their PASS devices.

April 16, 2007
Firefighter-Technician I Kyle Robert Wilson
Prince William County Department of Fire and Rescue, Virginia

Technician Wilson was assigned to Tower 512, a ladder company. Tower 512 was dispatched to a reported house fire at 0603 hours. The Prince William County area was under a high wind advisory as a nor’easter moved through the area. Sustained winds of 25 miles per hour with gusts up to 48 miles per hour were prevalent in the area at the time of the fire dispatch.

Initial arriving units reported heavy fire on the exterior of two sides of the single-family house, and crews suspected that the occupants were still inside the house sleeping because of the early morning hour. A search of the upstairs bedroom was conducted by Technician Wilson and his officer. A rapid and catastrophic change of fire and smoke conditions occurred in the interior of the house within minutes of Tower 512’s crew entering the structure. Technician Wilson became trapped and was unable to locate an immediate exit. “Mayday” radio transmissions of the life-threatening situation were made by crews and by Technician Wilson. Valiant and repeated rescue attempts to locate and remove Technician Wilson were made by the firefighting crews during extreme fire, heat, and smoke conditions. Firefighters were forced from the structure as the house began to collapse on them and fire conditions worsened. Technician Wilson succumbed to the fire and the cause of death was reported by the medical examiner to be thermal and inhalation injuries.

An extensive report on this incident is available from the Prince William Department of Fire and Rescue: Technician Kyle Wilson LODD Report.

For additional information regarding this incident, please refer to NIOSH Fire Fighter Fatality Investigation and Prevention Program Report F2007-12.

Ed Hartin, MS, EFO, MIFireE, CFO

Two incidents recently point to the hazards presented by explosions which may occur during firefighting operations.

Pittsburgh, PA

On March 25, 2009, firefighters in Pittsburgh, Pennsylvania were operating at a fire in a three-story apartment building of ordinary construction when an explosion occurred on Floor 2 while WPXI was videotaping fireground operations. Watch the video and see what you think?

• Did you observe any indicators of potential backdraft prior to the explosion?
• Do you think that this was a backdraft?
• What leads you to the conclusion that this was or was not a backdraft?
• If you do not think this was a backdraft, what might have been the cause of the explosion?

A news reporter quotes a chief officer, providing the following explanation: [Backdrafts] occur when a fire causes a buildup of pressure inside a building. When a firefighter enters a pressurized area, an influx of oxygen can cause the fire to explode. Note: comments reported in the press are not always an accurate representation of what was said.

While the comments reported are not completely inaccurate, they do not accurately describe the mechanism by which a backdraft occurs.

Cleveland, OH

On April 2, 2009, in Cleveland, Ohio an explosion occurred while firefighters were operating at a fire in a 2-1/2 story, wood frame dwelling. The fire, which had originated on the exterior of the structure, extended into the building and to the upper floors through void spaces in the balloon frame walls. According to news reports, the explosion occurred shortly after firefighters conducting primary search opened an attic door. The force of the explosion blew the two firefighters down the stairs to the second floor. Both firefighters received burns to the neck and face. News reports represented the phenomena involved in this event as a smoke explosion or backdraft.

• Based on the limited information provided in the news reports, which of these phenomena (backdraft or smoke explosion) do you think was most likely?
• What leads you to the conclusion as to which of these phenomena was most likely to have occurred?

A WKYC news report quoted a chief officer as stating “When they opened up the door to the attic that flow of oxygen allowed that fire to ignite, and it actually explodes.” Watch the video of this interview. This is a simple, but incomplete explanation of how a backdraft occurs. However, it does not explain the smoke explosion phenomena.

While smoke explosion and backdraft are often confused, there are fairly straightforward differences between these two extreme fire behavior phenomena. A smoke explosion involves ignition of pre-mixed fuel (smoke) and air that is within its flammable range and does not require mixing with air (increased ventilation) for ignition and deflagration. A backdraft on the other hand, requires a higher concentration of fuel that requires mixing with air (increased ventilation) in order for it to ignite and deflagration to occur. While the explanation is simple, it may be considerably more difficult to differentiate these two phenomena on the fireground as both involve explosive combustion.

While definitions are often ambiguous and the lines between various extreme fire behavior phenomena are a bit fuzzy, it is useful to examine even the limited information provided in news reports and give some thought to what might have happened. Are reported conditions consistent with the reported phenomena and what alternative theories might explain what happened?

Ed Hartin, MS, EFO, MIFIreE, CFO

My last post asked a number of questions focused on results of baseline compartment fire tests conducted by the National Institute for Standards and Technology (NIST) as part of a research project on  Firefighting Tactics Under Wind Driven Conditions.  This post looks at the answers to these questions and continues with an examination of NIST’s experiments in the application of wind control devices for anti-ventilation.

Questions

Generally being practically focused people, firefighters do not generally dig into research reports. However, the information on the baseline test conducted by NIST raised several interesting questions that have direct impact on safe and effective firefighting operations. First consider possible answers to the questions and then why this information is so important (the “So what?”!).

Figure 1. Heat Release Rate Comparison

Note: Adapted from Firefighting Tactics Under Wind Driven Conditions.

Heat Release Rate (HRR) Questions: Examine the heat release rate curves in Figure 1 and answer the following questions:

• Why are these two HRR curves different shapes?
• In each of these two cases, what might have influenced the rate of change (increase or decrease in HRR) and peak HRR?
• What observations can you make about conditions inside the test structure and heat release rate (in particular, compare the HRR and conditions at approximately 250 and 350 seconds)?

Answers: The HRR test for the bed and waste container was conducted under fuel controlled conditions (oxygen supply was not restricted). The higher HRR in the compartment fire experiment results from increased fuel load (e.g., additional furniture, carpet). After reaching its peak, HRR in the compartment fire drops off slowly as the fire becomes ventilation controlled and the fire continues in a relatively steady state of combustion (limited by the air supplied through the lower portion of the bedroom window)

The rate of change in heat release rate under fuel controlled conditions is dependent on the characteristics and configuration of the fuel.  However, in the case of the compartment fire test, the rate of change is also impacted by limited ventilation. As illustrated in the compartment fire curve, the fire quickly became ventilation controlled and HRR rose slowly until the window failed and was fully cleared by researchers.

At 250 seconds (when the window was vented) HRR rose extremely rapidly as the fire in the bedroom rapidly transitioned from the growth through flashover to fully developed stage. At 350 seconds the fire had again become ventilation controlled and was burning in a relatively steady state limited by the available oxygen.

The fully developed fire in the bedroom also became ventilation controlled due to limited ventilation openings, resulting in HRR leveling off with relatively steady state combustion based on the available oxygen.

Figure 2. Bedroom Temperature

Note: Adapted from Firefighting Tactics Under Wind Driven Conditions.

Temperature Questions: Examine the temperature curves in Figure 2 and answer the following questions:

• What can you determine from the temperature curves from ignition until approximately 250 seconds?
• How does temperature change at approximately 250 seconds? Why did this change occur and how does this relate to the data presented in the HRR curve for Experiment 1 (Figure 1)?
• What happens to the temperature at the upper, mid, and lower levels after around 275 seconds? Why does this happen?

Answers: Temperature at the upper levels of the compartment increased much more quickly than at the lower level and conditions in the compartment remained thermally stratified until the ceiling temperature exceeded 600^o C. At approximately 250 seconds, the compartment flashed over resulting in a rapid increase in temperature at mid and lower levels. This change correlates with the rapid increase in HRR occurring at approximately 250 seconds in Figure 1. Turbulent, ventilation controlled combustion resulted in a loss of thermal layering with temperatures in excess of 600^o C from ceiling to floor. At around 275 seconds.

Figure 3. Total Hydrocarbons at the Upper Level

Note: Adapted from Firefighting Tactics Under Wind Driven Conditions.

Total Hydrocarbons (THC) Questions: Examine the THC curves in Figure 3 and answer the following questions:

• Why did the THC concentration in the living room rise to a higher level than in the bedroom?
• Why didn’t the gas phase fuel in the living room burn?
• How did the concentration of THC in the bedroom reach approximately 4%? Why wasn’t this gas phase fuel consumed by the fire?

Answers: Oxygen entering the compartments through the window was being used by combustion occurring in the bedroom. Low oxygen concentration limited combustion in the living room and allowed accumulation of a higher concentration of unburned fuel. While the oxygen concentration in the bedroom was higher, the fire was still ventilation controlled and not all of the gas phase fuel was able to burn inside this compartment.

So What?

What do the answers to the preceding questions mean to a company crawling down a dark, smoky hallway with a hoseline or making a ventilation opening at a window or on the roof?

Emergency incidents do not generally occur in buildings equipped with thermocouples, heat flux gages, gas monitoring equipment, and pre-placed video and thermal imaging cameras. Understanding the likely sequence of fire development and influencing factors is critical to not being surprised by fire behavior phenomena. These tests clearly illustrated how burning regime (fuel or ventilation controlled) impacts fire development and how changes in ventilation can influence fire behavior. The total hydrocarbon concentration and ventilation controlled combustion in the living room would present a significant threat in an emergency incident. How might conditions change if the fire in the bedroom was controlled and oxygen concentration began to increase? Ignition of the gas phase fuel in this compartment could present a significant threat (see Fire Gas Ignitions) or even prove deadly (future posts will examine the deaths of a captain and engineer in a fire gas ignition in California).

Anti-Ventilation

For years firefighters throughout the United States have been taught that ventilation is “the planned and systematic removal of heat, smoke, and fire gases, and their replacement with fresh air”. This is not entirely true! Ventilation is simply the exchange of the atmosphere inside a compartment or building with that which is outside. This process goes on all the time. What we have thought of as ventilation, is actually tactical ventilation. This term was coined a number of years ago by my friend and colleague Paul Grimwood (London Fire Brigade, retired). It is essential to recognize that there are two sides to the ventilation equation, one is removal of the hot smoke and fire gases and the other is introduction of air. Increased ventilation can improve tenability of the interior environment, but under ventilation controlled conditions will result in increased heat release rate.

Another tactic change the ventilation profile and influence fire behavior and conditions inside the building is to confine the smoke and fire gases and limit introduction of air (oxygen) to the fire. Firefighters in the United States often think of this as confinement, but I prefer the English translation of the Swedish tactic, anti-ventilation. This is the planned and systematic confinement of heat, smoke, and fire gases and exclusion of fresh air. The concept of anti-ventilation is easily demonstrated by limiting the air inlet during a doll’s house demonstration (see Figure 4). Closing the inlet dramatically reduces heat release rate and if sustained, can result in extinguishment.

Figure 4. Anti-Ventilation in a Doll’s House Demonstration

For a more detailed discussion of the relationship between ventilation and heat release rate see my earlier post on Fuel and Ventilation.

Air Track and Influence of Wind

Air track (movement of smoke and air under fire conditions) is influenced by differences in density between hot smoke and cooler air and the location of ventilation openings. However, wind is an often unrecognized influence on compartment fire behavior. Wind direction and speed can influence movement of smoke, but more importantly it can have a dramatic influence on introduction of air to the fire.

While the comparison is not perfect, the effects of wind on a compartment fire can be similar to placing a supercharger on an internal combustion engine (see Figure 5). Both dramatically increase power (energy released per unit of time).

Figure 5. Influence of Wind

NIST Wind Control Device Tests

As discussed in Wind Driven Fires, the effects of wind on compartment fire behavior can present a significant threat to firefighters and has resulted in a substantive number of line-of-duty deaths. In their investigation of potential tactical options for dealing with wind driven fires, NIST researchers examined the use of wind control devices (WCD) to limit introduction of air through building openings (specifically windows in the fire compartment in a high-rise building) as illustrated in Figure 6.

Figure 6. Small Wind Control Device

Note: Photo from Firefighting Tactics Under Wind Driven Conditions.

Questions

Give some thought to how wind can influence compartment fire behavior and how a wind control device might mitigate that influence.

• How would a strong wind applied to an opening (such as the bedroom window in the NIST tests) influence fire behavior in the compartment of origin and other compartments in the structure?
• How would a wind control device deployed as illustrated in Figure 5 influence fire behavior?
• While the wind control device illustrated in Figure 5 was developed for use in high-rise buildings, what applications can you envision in a low-rise structure?
• What other anti-ventilation tactics could be used to deal with wind driven fires in the low-rise environment?

The Story Continues…

My next post will address the answers to these questions (please feel free to post your thoughts) and examine the results of NIST’s tests on the use of wind control devices for anti-ventilation.

References

Madrzykowski, D. & Kerber, S. (2009). Fire Fighting Tactics Under Wind Driven Conditions. Retrieved (in four parts) February 28, 2009 from http://www.nfpa.org/assets/files//PDF/Research/Wind_Driven_Report_Part1.pdf; http://www.nfpa.org/assets/files//PDF/Research/Wind_Driven_Report_Part2.pdf;http://www.nfpa.org/assets/files//PDF/Research/Wind_Driven_Report_Part3.pdf;http://www.nfpa.org/assets/files//PDF/Research/Wind_Driven_Report_Part4.pdf.

Ed Hartin, MS, EFO, MIFireE, CFO

The previous post (Shielded Fires) examined US Navy research on the effectiveness of different nozzle techniques when dealing with shielded fires conducted on the ex-USS Shadwell, the US Navy full scale damage control research facility (see Figure 1).

Figure 1. USS Shadwell

The researchers tested two different methods for controlling flaming combustion overhead while moving from the entry point to a location in a compartment where firefighters could make a direct attack on the seat of the fire. The first method involved use of a straight stream or narrow fog pattern and the second involved the use of a medium (60^o) fog pattern directed upward at a 45^o angle. In both cases, one to three second pulses were used in application of water into the hot gas layer.

US Navy Findings

Analysis of this series of tests resulted in identification of a number of specific findings related to tactics, equipment, and training. Three of these findings were particularly relevant to the differences between straight stream/narrow fog and medium fog applied to control flaming combustion in the upper layer.

• Pulsed application with a medium fog pattern directed upward at a 45^o angle resulted in less disruption of the thermal layer than use of a straight stream/narrow fog pattern.
• Use of a straight stream/narrow fog resulted in production of a large amount of steam. This was attributed to the fact that the hose streams had to be deflected compartment linings.
• Water management is important when controlling fire in the upper layer, particularly when using a straight stream/narrow fog. Excess water will only result in excess steam production.

Discussing the findings, the researchers observed that pulsed application of medium fog appeared to be an effective tactic for controlling flaming combustion in the upper layer. This conclusion is supported by consistent reduction of upper layer temperature over the course of the tests involving use of pulsed application of a medium fog pattern.  Previous concerns that this approach would result disruption of thermal layering and excess steam production appeared to be unfounded. This conclusion is supported by the heat flux data at 0.9 M (7′ 10″) and 2.9 M (3′) above the floor. Disruption of thermal layering is indicated by an upward spike in lower level heat flux or equalization of heat flux at the lower and upper levels.

Questions

Several questions about the outcome of these tests were posed at the end of the Shielded Fires post.

• Why did the application of water in a straight stream/narrow fog pattern fail to effectively control flaming combustion in the upper layer?
• Why did the upper layer temperature fluctuate when a straight stream/narrow fog was used?
• Why did the upper layer temperature drop consistently when a medium angle fog pattern was used?
• How did the heat flux measurements correlate with the upper layer temperatures in these two tests?
• What are the implications of the heat flux data recorded during these tests on tenability within the compartment for both firefighters and unprotected occupants?

Water converted to steam on contact with compartment linings or other hot objects cools the surfaces. This indirectly lowers gas layer temperature as the hot gases will continue to transfer heat to compartment linings and other cooler objects in an attempt to equalize temperature. However, the effect on upper layer temperature is limited, minimizing effectiveness of stream application in controlling flaming combustion in the upper layer. In addition, as gas temperature is not significantly reduced, steam produced on contact with hot surfaces is added to the volume of hot gases, resulting in a less tenable environment.

Ineffectiveness of straight stream/narrow fog attack in controlling flaming combustion in the upper layer and the perception of increased steam production with this type of attack likely have a common cause. Conversion of water to steam requires much more energy than simply heating water from ambient temperature to its boiling point. When water changes phase from liquid to gas (steam) while in the hot gas layer, the temperature of the gases is reduced. This has several consequences. First, sufficient reduction in temperature results in extinguishment of flaming combustion. Second, reduction of gas layer temperature causes a proportional reduction in gas volume. As illustrated in Figure 2, if 35% of the water is truned to steam in the hot gas layer, the total volume of steam and hot fire gases is less than the original volume of hot fire gases alone (Särdqvist, 2002). As this is often difficult to understand, I will provide a more detailed explanation of this in a subsequent post.

Figure 2. Gas Temperature and Relative Volume

Note. Adapted from Water and Other Extinguishing Agents (p. 155) by Stefan Särdqvist, 2002, Karlstad, Sweden: Raddningsverket. Copyright 2002 by Stefan Särdqvist and the Swedish Rescue Services Agency.

Production of the same volume of steam can have far different consequences depending on where it is produced (in the hot gas layer versus on contact with hot surfaces!

Total heat flux includes energy transferred through radiation, convection, and conduction. However, in these full scale fire tests, radiant and convective heat transfer was most significant. Radiant heat transfer is dependent on the temperature of upper layer gases and flaming combustion. Convective heat transfer is dependent on gas temperature, movement of hot gases, and moisture. Reduction in upper layer temperature while maintaining thermal layering minimizes total heat flux at the lower level where firefighters are working.

Other Considerations

These tests were conducted on a ship (see Figure 1) with most of the compartment linings being metal (rather than gypsum board, plaster, or wood as typically encountered in buildings. The fire compartment did not have windows or other ventilation openings that may exist in more typical buildings encountered by structural firefighters. These differences are significant, but do not diminish the importance of the results of these tests and findings by the researchers.

These tests provide substantive evidence in support of the effectiveness of water converted to steam in the hot gas layer (as opposed to on surfaces) in controlling flaming combustion in the hot gas layer. However, this does not diminish the importance of direct application of water onto burning fuel in a direct attack to complete the process of extinguishment.

Reference

Särdqvist, S. (2002). Water and other extinguishing agents. Karlstad, Sweden: Swedish Rescue Services Agency.

Scheffey, J., Siegmann, C., Toomey, T., Williams, F., & Farley J. (1997) 1994 Attack Team Workshop: Phase II-Full Scale Offensive Fog Attack Tests, NRL/MR/6180-97-7944. Washington, DC: United States Navy, Naval Sea Systems Command

Remember the Past

In Myth of the Self-Vented Fire I pointed out that every week represents the anniversary of the death of one or more firefighters as a result of extreme fire behavior. Some firefighters have heard about these incidents, but many have not. In an ongoing effort to encourage us to remember the lessons of the past and continue our study of fire behavior, I will occasionally be including brief narratives and links to NIOSH Death in the Line of Duty reports and other documentation in my posts.

February 11, 1998 – 1030
Firefighter Paramedic Patrick Joseph King
Firefighter Anthony E. Lockhart
Chicago Fire Department, Illinois

Firefighter King and Firefighter Lockhart responded on different companies to a report of a structural fire in a tire shop. No visible fire was encountered, there was no excessive heat, and only light smoke was found in most of the building with heavier smoke in the shop area. Ten firefighters were in the interior of the structure when an event that has been described as a flashover or backdraft occurred. The firefighters were disoriented by the effects of the backdraft. Some were able to escape but Firefighter King and Firefighter Lockhart were trapped in the structure. A garage door that self-operated due to fire exposure may have introduced oxygen into the fire area and may have been a factor in the backdraft. The exit efforts of firefighters were complicated by congestion in the building. Within minutes of the backdraft, the building was completely involved in fire and rescue efforts were impossible. Both firefighters died from carbon monoxide poisoning due to inhalation of smoke and soot. Further information related to this incident can be found in NIOSH Fire Fighter Fatality Investigation 98-F-05.

February 9, 2007
Firefighter-Paramedic Apprentice Racheal Michelle Wilson
Baltimore City Fire Department, Maryland

Firefighter Wilson and the members of her fire academy class were attending a live fire training exercise in a vacant rowhouse in Baltimore.

Firefighter Wilson was assigned to a group of apprentices and an instructor designated as Engine 1. Her group advanced a dry attack line into the structure. As they climbed the stairs, the line was charged. Engine 1 encountered and extinguished fire on the second floor but did not check the rest of the second floor for fire prior to proceeding to the third floor. On the third floor, they again encountered and began to extinguish fire.

Fire conditions began to worsen with a marked increase in smoke and heat that appeared to be coming from the second floor. Engine 1 firefighters who were on the stairs began to receive burns from the fire conditions. The instructor for Engine 1 climbed out a window at the top of the stairs and helped one burned firefighter escape to the roof.

Firefighter Wilson appeared at the window in obvious distress and attempted to escape. The windowsill was unusually high (41 inches) and she was unable to escape. Firefighter Wilson momentarily moved away from the window, at which time she advised other firefighters to go down the stairs to escape. When she returned to the window, her SCBA facepiece was off and she was beginning to receive burns. She was able to get her upper body out of the window but she could not make it through. Firefighters on the exterior were unable to pull her through until firefighters were able to gain access on the interior and assist with the effort.

When Firefighter Wilson was pulled to the roof, she was in full cardiac and respiratory arrest. She was immediately removed from the roof and received advanced life support care and transportation to the hospital. She was pronounced dead at 1250 hours. Firefighter Wilson received total body surface burns of 50 percent. The cause of death was listed as thermal burns and asphyxiation.

Further information related to this incident can be found in NIOSH Firefighter Fatality Investigation F2007-09 and the Independent Investigation Report on the Baltimore City Fire Department Live Fire Training Exercise, 145 South Calverton Road, February 9, 2007.

My next post will examine the incident in which Rachael Wilson lost her life in greater detail.

Ed Hartin, MS, EFO, MIFIreE, CFO

Water and Other Extinguishing Agents by Stefan Särdqvist was originally published (in Swedish) in 2001 by the Swedish Rescue Services Agency (now the Swedish Civil Contingencies Agency) and is used for training in practical firefighting operations. The English translation released in 2002 is an excellent resource for any firefighter or fire officer.

Särdqvist  has a PhD in Fire Protection Engineering, and his passion for this aspect of our profession is readily apparent in this text (and I mean this in the most positive way). Like Fire Ventilation by Stefan Svensson, Water and Other Extinguishing Agents effectively integrates science with the practical aspects of firefighting. Topics addressed in this text include:

1. Overview of Firefighting Operations
2. Water
3. Foam
4. Powder [Dry Chemical Agents]
5. Gaseous Extinguishing Agents
6. Extinguishing Theory

In the opening chapter, Särdqvist  states:

The fire triangle is sometimes used to describe the components needed to start a fire. The fire triangle has three sides: fuel, oxygen, and heat. In some cases an uninhibited chain reaction is added to the triangle to turn it into a four-sided tetrahedron. However, this approach is far too simple to explain why fires go out. It describes the ingredients needed for combustion, but not the mechanisms which cause fires to occur or to be extinguished. For this reason, the fire triangle cannot be used in discussions about extinguishing fires.

Sacrilege! For most of us the concept of the fire triangle and the fire tetrahedron are fundamental concepts applied to both occurrence of fire and fire control. Ah, but things are not as simple as we originally thought. The dominant method involved in fire extinguishment is cooling (with a few minor exceptions). Right at the start, this text challenges some commonly held (but scientifically incorrect) assumptions. 

In the chapter addressing water as an extinguishing agent, Särdqvist addresses water application methods including surface and smoke (gas) cooling. This chapter provides a sound explanation of why steam produced by water changing phase in the hot gas layer does simply add volume and lower the level of the hot gas layer. This is supported by a mathematical explanation of the expansion of steam and contraction of the hot gases as they are cooled. My colleague, Lieutenant Felepe Bazea Lehnert of the Valdivia Fire Department observed that “it is easier to explain this if you understand calculus”. However, Särdqvist does an excellent job of making these concepts accessible to a diverse fire service audience.

Water and Other Extinguishing Agents is available for on-line purchase from the Swedish Civil Contingencies Agency for 335 SEK (around $45.00) plus shipping. The agency will invoice for payment Swedish Kroner after your purchase (which necessitates using a bank that can produce a check in foreign currency).

Broken Links

Thanks to Lieutenant Matt Leech of Tualatin Valley Fire and Rescue for letting me know that there are a number of broken links in my earlier blog posts. A fix is in the works and hopefully all links will be functional by next Monday.

Historical Perspective

While researching the Iowa Fire Flow Formula, I came across some interesting information (trivia?) related to the use of water fog for firefighting. In The Safe and Effective Use of Fog Nozzles: Research and Practice, John Bertrand and John Wiseman observed that fog nozzles have been in existence for more than 100 years.. Early versions of this type of nozzle were imported to the United States from Europe.

In 1924, Glenn Griswold, a firefighter from Colorado Springs moved to California and joined the newly formed Los Angeles County Fire Protection District. He quickly rose to the rank of Captain and was assigned to Station 17 in Santa Fe Springs. Captain Griswold applied his prior education as a hydraulic engineer to the practice of firefighting and experimented with development of a nozzle to break water into small droplets. Eventually he patented the design under the name Fog Nozzle.

Subsequent innovations in the design of combination nozzles resulted in nozzles that could maintain the same flow rate regardless of pattern, adjustable flow nozzles could be set to provide different flow rates while maintaining consistent flow for all patterns, and finally automatic nozzles that maintained a relatively constant nozzle pressure through a specific flow range.

However, there was a reference to the January 1877 issue of Scientific American in Nelson’s Qualitative Fire Behavior that intrigued me. He stated that this article extolled the virture of little drops of water and the latent heat of steam and that it attempted to point out in a scientific manner that spray or fog nozzles could greatly increase the efficiency of the fire service.

I located a copy of the magazine in the archives of the Portland State University library. The article that Nelson referenced, was actually a letter to the editor written by Charles Oyston of Little Falls, NY.

Scientific American, January 1877

To the Editor of the Scientific American

In our issue of December 30, you recommend discharging water through perforated pipes in the form of spray for extinguishing fire. If water in the form of spray be a good extinguisher, as it undoubtedly is, as numbers of proofs exist in our factories and picker rooms, why do not our fire departments use it in that form in all cases where they can? Leaving firemen to answer that question, I will proceed to adduce a few facts in support of the theory that a spray is the true method of applying water wherever the burning object can be reached by it.

Water operates, in extinguishing fire, by absorbing the heat and reducing the temperature of the burning substance so low that fire cannot exist; and as the amount of heat that water will absorb depends on the amount of surface of water in contact with the fire, the more surface we can cover with a given amount of water the better. As flame is the principle propagator of fire, to arrest it is the first thing to do; and as it is more than three thousand times lighter than water, and in most cases a mere shell or curtain, a fraction of an inch thick, the extreme absurdity of trying to subdue it with solid streams of water will be apparent. If a man in the character of a sportsman were to fire an inch ball into a flock of humming birds, with the intention of killing as many as possible, he would be regarded as a fool; but if he were to melt the inch ball up, and cast it into shot one thirtieth of an inch in diameter, he would have twenty-seven thousand such shot, and their aggregate surface would be thirty times greater than the inch ball. If he were to load his gun with this shot and fire into the flock, at proper distance, the slaughter of the little beauties would be terrible; and if a fireman would divide up his stream into spray, so that he could cover thirty times more flame, he might expect a corresponding result. The globules of water would be so small that a large portion of them would be heated through and converted into steam; and as steam contains five more heat (latent) than boiling water, we gain a great advantage in this. Steam is also an excellent extinguisher, and this is an additional advantage. As a large portion of this water is converted into steam when applied in the form of a pray, a small amount serves, and the damage by water is very small.

If the first two engines that reached the burning Brooklyn theater could throw five hundred gallons of water each minute, and divide every cubic inch of water into sixty thousand drops, in two minutes the smoke and heat would have been sufficiently subdued to have enabled outsiders to enter and rescue the unfortunate inmates. I am well aware that this statement may seem extremely absurd to firemen who have never experimented in this line; but before they condemn it, let them take out a couple of engines and try the experiment. The barbarous system now in use that so frequently desolates portions of our cities, fills our houses with mourning and our cemeteries with new-made graves, must give way to the dictates of Science. Humanity demands it, and I call on the scientists and chemists throughout the land to aid in introducing this needed reform.

Little Falls, N.Y. Charles Oyston
Scientific American Vol. XXXVI No. 4, Page 52
January 27, 1817

The Rest of the Story

Oyston does not mention that he holds a patent for a device called Improvement in Nozzles which used a series of movable hooks inside a relatively standard solid stream nozzle to create a broken stream pattern of broken droplets. In the Fire Stream Management Handbook, David Fornell astutely observes that attempting to introduce change in the 19th century was apparently as difficult as it is today.

While it is obvious that Oyston is not a firefighter or fire protection engineer with a sound understanding of the tactical applications of straight streams and water fog in firefighting operations, he did have a reasonable grasp of the basic physics involved in the use of cooling for fire control and extinguishment.

His call for scientists and chemists to weigh in on the issue resonated strongly with me as firefighters stand across a chasm from scientists, engineers, and researchers. Much progress has been made in this regard in other nations such as Sweden and in the US by the work of the National Institute for Standards and Technology (NIST) and others. However, this integration of science with the practical experience of firefighting needs to continue and be expanded.

Ed Hartin, MS, EFO, MIFireE, CFO