Posts Tagged ‘fire behavior indicators’

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. While video provides the opportunity to observe fire behavior indicators over time, still photos also an excellent tool for practice your skill in reading the fire.

Smoke Showing Photography

This Reading the Fire exercise is based on a photo taken by Scott LaPrade, a firefighter assigned to Ladder 1 in Leominster, Massachusetts. Scott has been photographing fires around New England for 25 years. His website, Smoke Showing Photography is an excellent resource when looking for fire photos to practice reading the fire.

Apartment Fire

On February 6, 2009, the Leominster Fire Department received a call for smoke in the building at 77 Cedar Street. Ladder 1 was first due and reported smoke showing from a three-story wood frame apartment building originally built in the 1900s.

Initially light smoke was showing from the roof, but then appeared to dissipate. After companies made entry to investigate, the fire progressed rapidly.

Download and print the B-SAHF Worksheet. Consider the information provided above and examine the following photo. First, describe what you observe in terms of the Building, Smoke, Air Track, Heat, and Flame Indicators. Second, answer the following six questions:

1. What stage(s) may the fire be in (incipient, growth, fully developed, or decay)?
2. What burning regime is the fire likely to be in (fuel or ventilation controlled)?
3. What conditions would you expect to find inside the doorway in the photo?
4. What hazards does the firefighter in does the firefighter in the photo face while working in the doorway?
5. How could these hazards be mitigated?
6. If the fire is on Floor 1 (it was), what are likely avenues for extension in this type of building construction?

Note the kink in the 1-3/4″ (45 mm) hoseline behind the firefighter. Kinks can dramatically reduce flow rate. Watch your hoseline as well as the B-SAHF indicators!

Visit Scott’s website Smoke Showing Photography for additional photos of this incident and extend your practice in Reading the Fire.

Ed Hartin, MS, EFO, MIFireE, CFO

Deliberate Practice

As discussed in my posts on Outstanding Performance and Reading the Fire improving proficiency requires sustained deliberate practice!

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

Download and print the B-SAHF Worksheet and then view the first 45 seconds of the following video of conditions on Side C of a residential fire as the crew of Toronto Pumper 223 makes entry into a window on Floor 2, Side A to check for extension from a fire in the basement. First, describe what you observe in terms of the Building, Smoke, Air Track, Heat, and Flame Indicators. Second, answer the following five questions:

1. What additional information would you like to have> How could you obtain it?
2. What state(s) of fire development is the fire likely to be in (incipient, growth, fully developed, or decay)? Remember that fire in adjacent compartments can be in a different stage of development?
3. What burning regime is the fire in (fuel or ventilation controlled)?
4. What conditions would you expect to find on Floor 2? Is the environment tenable for properly protected firefighters?
5. Is it likely that the fire has extended to Floor 2? Why or why not?
6. How would you expect the fire to develop over the next two to three minutes

Find more videos like this on firevideo.net

Back the video up to the beginning and then watch the first three minutes of the clip and consider the following questions:

1. What changes in indicators did you observe prior to the egress of the crew of Pumper 223 from Floor 2?
2. What changes in indicators did you observe following their egress from Floor 2?
3. What might have caused the change in conditions while the crew of Pumper 223 was checking for extension
4. Were there significant indicators of worsening fire behavior visible from the exterior prior to the egress of the members working on Floor 2?
5. What indicators of changing conditions would you have expected on the interior of Floor 2?
6. What tactical options might have reduced the probability of developing untenable conditions on Floor 2?
7. Review your answers on the B-SAHF worksheet. Did any of your answers change based on the additional information provided by the second segment of the video clip? Did you successfully predict the fire behavior that occurred?

After completing the B-SAHF exercise, view the remainder of the video. Placement of the tip of the ladder above the window sill made egress from Floor 2 a bit more difficult. However, Captain Mark Fitzsimmons and Firefighters Geoff Mortimer and Mark Ashcroft from Toronto Pumper 223 escaped without serious harm because they recognized changing conditions and quickly made the decision to exit.

As noted in my earlier post on Flashover & Survival Skills it is essential to train on emergency procedures, but it is even more important to ensure that firefighters and officers are proficient at reading the fire and managing the fire environment to reduce the probability that emergency procedures will be required.

Comments Fixed!

Thanks to Dr. Stefan Svensson for alerting me to a problem with the comments feature of the blog. The problem has been fixed and you can now provide feedback on the posts in the CFBT Blog. Please feel free to do so!

Ed Hartin, MS, EFO, MIFireE, CFO

Deliberate Practice

As discussed in my posts on Outstanding Performance and Reading the Fire improving proficiency requires sustained deliberate practice!

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.

Commercial Fire

Download and print the B-SAHF Worksheet and then view the first 8 seconds of the following video of conditions on Side C of a commercial fire. First, describe what you observe in terms of the Building, Smoke, Air Track, Heat, and Flame Indicators. Second, answer the following five questions:

1. What additional information would you like to have?
   How could you obtain it?
2. What state(s) of fire development is the fire likely to be in (incipient, growth, fully developed, or decay)? Remember that fire in adjacent compartments can be in a different stage of development?
3. What burning regime is the fire in (fuel or ventilation controlled)?
4. What conditions would you expect to find inside this building? Is this likely to be a survivable environment for unprotected occupants? For firefighters?
5. How would you expect the fire to develop over the next two to three minutes?

Find more videos like this on firevideo.net
Back the video up to the beginning, watch the first 15 seconds, and review your answers on the B-SAHF worksheet. Did any of your answers change based on the additional information provided by the view of Side A?
After completing the B-SAHF exercise, view the remainder of the video. Did you successfully predict the fire behavior that occurred? This video provides excellent examples of smoke and air track indicators. However, sometimes the indicators of potential for extreme fire behavior might not be so obvious. Under these circumstances, you will need a higher level of skill to anticipate fire development.

Make it a Habit!

As Geoff Colvin emphasizes in Tallent is Overrated the quantity and quality of deliberate practice is the major determinant in expertise at all levels from novice to expert. Developing skill in reading the fire requires practice. Additional B-SAHF exercises will be posted on a regular basis at cfbt-us.com. Also check the CFBT-US Resources page for additional information on Reading the Fire!

Consider making B-SAHF exercises a regular part of your training schedule. During a recent Compartment Fire Behavior Training (CFBT) Instructor course conducted at Tualatin Valley Fire & Rescue we used B-SAHF drills each morning to help the participants develop skill in reading the fire. However, these drills are equally appropriate for recruit firefighters. Understanding fire behavior and the ability to read the fire and anticipate changes in fire development are critical for everyone working on the fireground!

Ed Hartin, MS, EFO, MIFireE, CFO

Photo by Mark E. Brady, Prince Georges County Fire/EMS Department

Experienced Judgment

Firefighters frequently base their expectations of how a fire will behave on their experience. Wildland fire scientist Harry Gisborne’s1948 observations about wildland firefighters experienced judgment can be paraphrased to apply to structural firefighters as well:

For what is experienced judgment except opinion based on knowledge acquired by experience? If you have fought fires in every type of building with every different configuration and fuel load, under all types of conditions, and if you have remembered exactly what happened in each of these combinations your experienced judgment is probably very good

Unfortunately this is rarely the case. Firefighters and fire officers often have limited experience and do not have sufficient understanding of fire dynamics to recognize potential for extreme fire behavior.

Riverdale Flashover

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. Probationary Firefighter Tony George captured initial operations in a series of four photos taken over a period of two minutes.

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.

• What can be inferred from these observations?
• What is the stage of fire development and burning regime?

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).

• Has your perception of fire conditions changed?
• Why did fire conditions change after the door was opened?

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). The crew from Engine 813 experiences a burst hoseline, delaying fire attack.

• If the fire was ventilation controlled prior to opening the door, how are fire conditions likely to change?
• If the truck crew increases ventilation by opening windows, how will this influence fire development?
• What is the potential impact of the delay in deployment of a hoseline to attack the fire?

Two minutes after the first photo, and shortly after the crew from Truck 807 made entry, flashover occurred.

According to a press release from Prince Georges County Fire/EMS Department Chief Spokesperson Mark Brady:

The engine from Riverdale Heights arrived first and advanced a hoseline to the front door and paused to don their personal protective equipment (PPE) and self contained breathing apparatus (SCBA). The house was vacant and a small fire could be seen in the front living room. The ladder truck from Riverdale Fire/EMS Station #807 was the second to arrive, almost at the same time as Riverdale Heights. The crew from Truck 807 donned their PPE and SCBA and entered the structure to begin ventilation by removing windows. As the engine crew from Riverdale Heights prepared to enter the structure and extinguish the fire their hoseline sustained damage from glass or debris and was cut; rendering it useless. As additional arriving firefighters stretched another hoseline into position, a flashover occurred.

Two firefighters involved in this incident were seriously injured, FF Johnston was treated and released. FF Blazek was admitted to the MedStar Burn unit. Visit the Riverdale Volunteer Fire Department Web Site for updates on FF Blazek’s condition.

Things to Think About

Near misses and injuries such as occurred during this incident happen all too frequently. All too often, firefighters and officers consider this to be part of the job. Fire behavior is extremely predictable. It will do the same thing every single time under the same conditions. The problem is that the conditions are seldom exactly the same and our experienced judgment is not perfect.

What can you do to reduce the risk of being surprised by extreme fire behavior? Become (or continue to be) a student of your craft and develop an improved understanding of fire dynamics and the influence of tactical operations on fire behavior. Practice reading the fire (see my earlier post Reading the Fire: B-SAHF) using photos, video, and every fire you respond to.

Ed Hartin, MS, EFO, MIFireE, CFO

What is a smoke explosion? Is it the same thing as a backdraft or is it a completely different phenomenon? In one form or another I have encountered this question several times during the last week. In one case, I was asked to review a short article about an incident involving a smoke explosion that was submitted to FireRescue magazine. In another case, I was surfing the web and came across the following video titled large smoke explosion close call on firevideo.net. What happened in this incident? Was it a smoke explosion or a backdraft?

Find more videos like this on firevideo.net

What’s in a Name?

For many years, the term smoke explosion was a synonym for backdraft. In fact, if you look up the definition of smoke explosion in the National Fire Protection Association (NFPA) 921 (2007) Guide for Fire and Explosion Investigation, it says “see backdraft“. However, smoke explosion is actually a different, and in many respects more dangerous extreme fire behavior phenomenon.

Smoke explosion is described in a number of fire dynamics texts including Enclosure Fire Dynamics (Karlsson and Quintiere) and An Introduction to Fire Dynamics (Drysdale). However, Enclosure Fires by Swedish Fire Protection Engineer Lars-G�ran Bengtsson provides the most detailed explanation of this phenomenon. Paraphrasing this explanation:

A smoke or fire gas explosion occurs when unburned pyrolysis products and flammable products of combustion accumulate and mix with air, forming a flammable mixture and introduction of a source of ignition results in a violent explosion of the pre-mixed fuel gases and air. This phenomenon generally occurs remote from the fire (as in an attached exposure) or after fire control.

In some cases, the fire serves as a source of ignition as it extends into the void or compartment containing the flammable mixture of smoke(fuel) and air. This was the case in Evanston, Wyoming, where two firefighters died as the result of a smoke explosion in a two-story wood frame townhouse (see National Institute for Occupational Safety and Health (NIOSH) Report F2005-13). In other cases, firefighters may unintentionally provide the source of ignition. On 26 March 2008, a Los Angeles City firefighter was killed when he attempted to force entry into an electrical room filled with smoke from a manhole fire in the adjacent street. (see LAFD News and Information). Battalion Chief John Miller, Commanding Officer of the LAFD Arson/Counter-Terrorism Section reported:

This combustible smoke accumulated in the confined area of the electrical room. When Firefighter Lovrien attempted entry into the room, a spark was generated when the composite blade of the rotary saw struck the locking mechanism of the door… Investigators have concluded that unburned combustible gases, from a fire in the electrical vault located in the street at the front of the building, accumulated in the electrical room. These products of combustion reached its explosive limit and was ignited by a spark from the forcible entry attempts

Conditions Required for a Smoke Explosion

The risk of a smoke explosion is greatest in compartments or void spaces adjacent to, but not yet involved in fire. Infiltration of smoke through void spaces or other conduits can result in a well mixed volume of smoke (fuel) and air. Smoke explosion creates a significant overpressure as the fuel and air are premixed and ignition results in a very large energy release. Several factors influence the violence of this type of explosion:

• The degree of confinement (more confinement results in increased overpressure)
• Mass of premixed fuel and air within the flammable range (more premixed fuel results in a larger energy release)
• How close the mixture is to a stoichiometric concentration (the closer to an ideal mixture the faster the deflagration)

Potential Smoke Explosion Indicators

It is very difficult to predict a smoke explosion. However, the following indicators point to the potential for this phenomenon to occur:

• Ventilation controlled fire (inefficient combustion producing substantial amounts of unburned pyrolysis products and flammable products of incomplete combustion)
• Relatively cool (generally less than 600^o C or 1112^o F) smoke
• Presence of void spaces, particularly if they are interconnected
• Combustible structural elements
• Infiltration of significant amounts of smoke into uninvolved compartments in the fire building or into exposures

Smoke Explosion and Backdraft

A smoke explosion requires a relatively cool mixture of fuel (smoke) and air within its flammable range to come into contact with a source of ignition. On the other hand a backdraft requires introduction of air to an hot, extremely ventilation controlled fire where the concentration of gas phase fuel (smoke) is high and oxygen concentration is low. Both result in an explosion, but the initiating event and indicators that may be observed by firefighters and fire officers are considerably different.

Have another look at the video and see what you think: Smoke explosion or backdraft? Remember that both of these phenomena can occur in a building, a compartment, or even a small void space. Look closely at the building, smoke, air track, heat, and flame (B-SAHF) indicators. Check CFBT-US Resources more information on extreme fire behavior and reading the fire.

Ed Hartin, MS, EFO, MIFireE, CFO

Previous posts examined key factors and initial company operations at a residential fire involving flashover that resulted in multiple firefighter injuries at a residential fire in Loudoun County, Virginia. This post will examine the action taken by the trapped firefighters and crews on the exterior.

Reserve Engine 6 was performing fire attack on Floor 2 and Tower 6 had just completed searching the second floor when they experienced a rapid increase in temperature and thickening smoke conditions. Flames were extending from the first floor, up the open foyer and staircase, trapping the two crews on Floor 2.

When the firefighter from Reserve Engine 6 opened the nozzle, the line immediately lost pressure. The engine company officer attempted to diagnose the problem without success. Unknown to the engine crew, the hoseline had partially failed approximately 10′ from the nozzle, drastically reducing the available flow. Lacking an effective stream, the engine crew moved down the hallway towards Bedroom 2 in an attempt to find an alternate means of egress.

Partial collapse of the ceiling separated the Tower 6 firefighter and officer. The firefighter joined up with the crew from Reserve Engine 6 in Bedroom 2. The Tower 6 firefighter partially closed the bedroom door, providing some relief from the increasing temperature. The two firefighters and officer trapped in Bedroom 2 were able to escape over a ladder placed on Side Charlie by the apparatus operator of Reserve Engine 6. It is likely that this quick action by the tower firefighter in closing the door had a significant impact on the tenability of Bedroom 2 for the time required for these three individuals to escape.

Trapped in the Master Bedroom, the officer from Tower 6 attempted to break a window to escape the increasing temperature and thick smoke, but was unable to do so. He exited the master bedroom and eventually escaped through an unspecified window on Floor 2, Side Charlie.

Several factors contributed to the survival of the crews working on floor 2:

• Proper use of personal protective equipment
• Recognition of rapidly deteriorating conditions
• Immediate action to locate an alternate means of egress
• Availability of a secondary egress route provided by the ladders placed by the apparatus operators of the tower and engine
• Closing of the door to Bedroom 2 to increase tenability during emergency egress

Read the report for additional detail on this incident.

The crews of Reserve Engine 6 and Tower 6 who were on Floor 2 had completed survival skills and flashover training. Training and quick reactions contributed to their survival, but increased situational awareness, earlier recognition of developing fire conditions, and control of the fire environment would likely have prevented this accident.

The next post will examine key issues in training focused on “reading smoke” as well as flashover and survival skills training.

Ed Hartin, MS, EFO, MIFireE, CFO

My last post provided an overview of the factors influencing the occurrence of flashover and multiple firefighter injuries at a residential fire in Loudoun County Virginia identified in the report released by Loudoun County Fire, Rescue, and Emergency Management. Let’s look at the events that occurred from the time of dispatch until flashover occurred.

Loudoun County Emergency Communications Center (ECC) dispatched four engines, a truck, rescue, ambulance and two chief officers were dispatched to a reported house fire at 43238 Meadowood Court. The caller reported a fire in the area of the sunroom on the first floor of the home at this address with smoke coming from the roof. Subsequent callers reported heavy smoke in the area. While the call taker received information about the location of the fire in the building, the dispatcher did not pass this information to responding companies.

The first arriving company, Reserve Engine 6 reported that the building was a two-story, single-family dwelling with a fire in the attic or running Side Charlie. Uncertain of the status of building occupants, the engine company officer assigned the truck to perform primary search.

As part of his size-up, the engine company officer walked from Side Alpha around Side Delta to the Charlie/Delta corner to assess conditions. Unfortunately, from this position, he was unable to observe the fire in the area of the sunroom on Floor 1; this factor would become extremely significant over the next seven minutes.

Reserve Engine 6 was staffed with a crew of three, and the firefighter and officer extended a 200′ 1-3/4″ (60.96 M 45 mm) preconnected hoseline to the door on Side Alpha. As the hoseline was being deployed Tower 6, also with a crew of three, arrived on scene and the tower officer and firefighter joined the engine crew at the front door.

When they entered the building, the crews of Reserve Engine 6 and Tower 6 encountered moderately thick smoke and no significant increase in temperature in the two-story (open) foyer. The smoke was thick enough that they had some difficulty in locating the interior staircase. There is no indication that either crew picked up on the presence of significant smoke on Floor 1 as a violation of their expectation of a fire on Floor 2 or in the attic or a potential indicator that there may be a fire on Floor 1.

As they proceeded up the stairs, the crews of Reserve Engine 6 and Tower 6 did not encounter an appreciable change in conditions. Smoke remained moderate, with no significant increase in temperature. Reaching the top of the stairs, the engine crew turned right towards the Master Bedroom. The crew from Tower 6 went left into Bedroom 1 and conducted primary search, venting a window on Side Alpha. The report does not mention if the crew of Tower 6 closed the door to the bedroom while conducting their search or the position of the door when they completed their search of this room and continued to Bedroom 2.

Computer modeling of fire development in this incident has not yet been completed and the report does not indicate that this change in ventilation profile was a significant factor in the occurrence of flashover or extension of flames to Floor 2. However, presence or creation of an air track with crews working between the fire and exhaust opening has been a factor in other incidents. For example, see NIOSH Report 99-F21 and F2000-04 as well as NIST Reports 6854 and 6510.

Entering the master bedroom, the crew of Reserve Engine 6 encountered thick smoke, an increase in temperature, and observed flames on the opposite side of the room (Side Charlie). The officer directed the firefighter to attack the fire while he opened a window on Side Charlie. Tower 6 completed the primary search of Bedroom 2 (no mention of the tower crew making any ventilation openings in Bedroom 2) and then completed a search of Bedroom 3. After finishing the search of Floor 2, the Tower determined the need to pull ceilings for Reserve Engine 6, but doe to the height of the ceiling, did not have tools long enough to accomplish this task.

While crews were working on the interior, the apparatus operator of Tower 6 placed a ladder on Side Alpha to a window in Bedroom 3, removing approximately 2/3 of the glass from the opening. The apparatus operator of Reserve Engine 6 placed a ladder on Side Charlie to a window in Bedroom 2, which broke, but did not remove the glass.

A chief officer arrived and assumed Command on Side Alpha. Command assigned the second chief, who arrived a short time later to perform reconnaissance on Side Charlie. In his transfer of command radio report, the officer of Reserve Engine 6 indicated that the fire was in the attic. Command confirmed that there were flames visible from the attic ridge vents and flames were visible from both sides.

On the interior, the crews of Reserve Engine 6 and Tower 6 experienced a rapid increase in temperature and thickening smoke conditions. The crew of Tower 6, who were exiting to obtain longer tools, encountered flames coming up the open foyer and staircase from the first floor.

MAYDAY, MAYDAY, MAYDAY! Due to a problem with his radio, the tower officer, directed his firefighter to transmit a Mayday message. Concurrently, second arriving chief reported a collapse on Side Charlie.

As with many other incidents resulting in serious injuries or fatalities, this “appeared to be a routine incident”. Companies initiated standard firefighting tactics based on their assessment of incident conditions and the problems presented. The following three events contributed significantly to limited situational awareness:

1. Limited information provided by dispatch
2. Completing a 180^oreconnaissance rather than viewing all sides of the structure
3. Not recognizing key smoke indicators (location, thickness) on Floor 1

While not identified in the report, changing the ventilation profile by opening windows on Floor 2 (possibly based on the assumption that the fire was on Floor 2 or in the attic and the placement of a hoseline by Reserve Engine 6) may have had a negative influence on fire behavior. On the other hand, the placement of ladders to second floor windows by the apparatus operators of the engine and tower provided alternate means of egress for the crews trapped on Floor 2.

Read the report for additional detail on this incident.

The next post will examine the actions taken by Reserve Engine 6 and Tower 6 that aided in their escape from the extreme conditions encountered on Floor 2.

Ed Hartin, MS, EFO, MIFireE, CFO