Posts Tagged ‘Fire Control’

Application of the appropriate flow rate is critical to fire control. However, how can we estimate the flow rate that is necessary?

There are a number of methods that can be used to estimate or calculate required flow rate for fire control. One method is to simply use your experience (which may work quite well if you have been to a large number of fires and paid attention to flow rate). However, if you do not have a large base of experience to draw on or need to apply flow rate estimation in a preplanning context, other methods are necessary. One of the most common methods used in the United States is the National Fire Academy (NFA) Fire Flow Formula.

Development of the NFA Formula

In the mid 1980s the development team for the National Fire Academy Field course Preparing for Incident Command developed this formula to provide a simple method for estimating the flow requirements for offensive, interior operations where a direct attack was used to control and extinguish the fire.

Interestingly enough the NFA Fire Flow Formula is not based on science (at least not physical science). The developers tapped into another valid source of information, knowledge of experienced fire officers.

The course developers designed a number of plot and floor plans showing different sizes of building with different configurations (e.g., rooms, doors, windows) with varied levels of involvement. These drawings were distributed to students attending the academy and they were asked how their fire department would control the fire (with the emphasis on the number, placement, and flow rate of hoselines).

There are three major parameters used for the scenarios based on these plot and floor plans.

• All scenarios were designed to involve offensive, interior firefighting operations and as such, fire involvement was limited to 50% or less of the total floor area of the building.
• Operations were to be conducted as they normally would, with initial operations started by the first arriving company and additional tactics implemented as resources arrive.
• Primary search and ventilation tactics would be performed concurrently with fire control operations.

The student’s responses were collected and analyzed. For each scenario, when the floor area of the involved area in square feet (ft²) was divided by the total flow rate in gallons per minute (gpm) for all hoselines used for attack, backup, and exposure protection; the average result was three. Turning this around, flow rate in gpm can be determined by dividing the area of involvement in ft² by three.

In that the exterior of the building can be determined more easily than the area of involvement, the formula was adapted to determine the flow rate based on building size and approximate percentage of involvement as illustrated below:

Note: This method does not translate easily into standard international (SI), simply converted the formula would be lpm = M²/0.07.

The course development team extended the application of this formula to include estimated flow required for exposure protection by adding 25% of the flow rate required for fire control (as determined by the basic formula) for each exposure. The full formula as used in preplan development is as follows:

The development team believed that this formula would also be applicable to defensive attack for levels of involvement above 50%. However, this was not validated using the same type of methodology as used to develop the base fire flow formula.

Limitations

It is important to remember the limitations of this fire flow estimation method:

• The NFA Fire Flow Formula is designed for offensive, interior operations involving direct attack.
• The formula becomes increasingly inaccurate if the level of involvement exceeds 50% or the resulting flow is greater than 1,000 gpm.
• This method is not designed for defensive, master stream operations (even though the developers believed that it would provide a reasonable estimate of required flow rate for defense.
• The formula is based on area, not volume. If the ceiling height exceeds 10’, the flow rate may be underestimated.
• The NFA Formula does not take into account the potential heat release rate of the fuel. Fuel with extremely high heat release rate may require a higher flow rate
• The developers of the NFA Formula made the assumption that the building was well ventilated (tactically). Increased ventilation can (if the fire is initially ventilation controlled) result in increased heat release rate.
• It may be tough to do the math at 0200 hours when faced with a rapidly developing fire! This method is best used in advance of the fire when developing preplans or working on tactical problems

Total Versus Tactical Rate of Flow

The most common application error is the belief that the formula determines the flow rate required for fire attack. This is incorrect! The formula determines the total flow rate required for attack, backup, and exposure protection lines. Use of this formula to determine the flow rate for the initial attack line (or lines) will greatly overestimate the required tactical rate of flow.

As discussed in It’s the GPM! and Choose your Weapon Part I, substantially exceeding the required tactical rate of flow has diminishing returns on speed of extinguishment and substantially increases the amount of water used. If excessive, water that is not used efficiently (i.e., turned to steam) increases fire control damage).

Using the NFA Base Fire Flow Formula (no exposures), roughly half of the flow rate is used for attack lines and the remainder is used for backup lines. The NFA formula provides an excellent method for estimating total flow rate requirements (which impacts on water supply and resource requirements). However, it must be adjusted (reduced by half) to determine the tactical rate of flow necessary for direct attack on the fire.

Other Approaches

As outlined in this post, the NFA Fire Flow Formula is intended for estimating the total flow rate required when making a direct attack and has a number of specific parameters that must be considered. Prior to introduction of the NFA formula, the Iowa Fire Flow Formula developed by Floyd W. (Bill) Nelson and Keith Royer. The Iowa Formula was developed quite differently, has substantially different assumptions, and will be the subject of my next post.

For more information on Fire Flow, visit my colleague Paul Grimwood’s website www.fire-flows.com. Paul has amassed a tremendous amount of information on this topic from around the world.

Ed Hartin, MS, EFO, MIFireE, CFO

Applying NIOSH Recommendations

NIOSH Death in the Line of Duty reports generally contain two types of recommendations, those that focus on specific contributory factors and others that address general good practice. As when examining contributory factors, it is important to read the NIOSH recommendations critically. Do you agree or disagree and why? What would you change and what additional recommendations would you make based on the information presented in the report?

Brief Review of the Incident

NIOSH Report F2008-06 examines a fire in a wood frame duplex that resulted in injury to Lieutenant Scott King and the death of Firefighter Brad Holmes of the Pine Township Engine Company. The fire occurred on February 29, 2008 in Grove City, Pennsylvania.

When the fire department arrived, the unit on Side D was substantially involved and a female occupant was reported trapped in the building. Initial operations focused on fire control and primary search of Exposure B. Rapid fire development trapped Lieutenant King and Firefighter Holmes while they were searching Floor 2 of Exposure B.

The following photographs are part of a series of 37 pictures taken during this incident and provided to NIOSH investigators during their investigation.

Additional detail on this incident is provided in Developing & Using Case Studies: Pennsylvania Duplex Fire Line of Duty Death (LODD) and Pennsylvania Duplex Fire: Firefighting & Firefighter Rescue Operations . In addition, readers should review NIOSH Report F2008-06.

Recommendations

NIOSH Report F2008-06 contains 11 recommendations. Several of these recommendations are well grounded in the contributory factors identified in the report. Others have a more indirect relationship to the factors influencing the injury to Lieutenant King and death of Firefighter Holmes.

Recommendation #1: Fire departments should be prepared to use alternative water supplies during cold temperatures in areas where hydrants are prone to freezing.

In preparation for potential issues, fire departments should develop standard operating procedures (SOPs) for temporary water sources to be dispatched like tankers, water shuttles, or portable drop tanks.

While this recommendation is valid and good practice, it has little to do with loss of water as a contributory and likely causal factor in the injury to Lieutenant King and death of Firefighter Holmes. Had Command been notified immediately of the frozen hydrant and implemented alternate water supply strategies, the outcome would have likely been the same if tank water had been used as it was in this incident to sustain initial operations.

However, it is critical for fire departments to have a plan to respond to respond to water supply problems. In this case, apparatus had substantial tank water which was used to support initial firefighting operations. In addition, there was sufficient hose available on first alarm companies to stretch to other hydrants (such as the one eventually used east of Garden Avenue on Craig Street). Use of a reverse lay to establish water supply allows the apparatus operator to continue the lay to the next hydrant (hose capacity permitting) or another apparatus to continue the lay and establish a relay. Depending on the distance to the next operational water source, this could be considerably more efficient and rapid than waiting for greater alarm resources to establish a tender shuttle.

Recommendation #2: Fire departments should ensure that search and rescue crews advance or are protected with a charged hoseline.

This recommendation is critical. However, the discussion fails to speak to the need for backup lines to protect the means of egress when crews are working above the fire. Recent incidents in Loudoun County, Virginia and Sacramento California, resulted in crews with a hoseline working above the fire without a backup line having their hose burn through, and means of egress cut off, necessitating emergency egress via second floor windows.

Recommendation #3: Fire departments should ensure fire fighters are trained in the tactics of a defensive search.

While training in search under marginal circumstances is important, this recommendation fails to speak to the need to understand fire behavior and applied fire dynamics as a foundation for maintaining situational awareness on the fireground. This applies to command personnel, company officers, and individual firefighters. While there are a number of points in the sequence of events that lead to Lieutenant King’s injury and Firefighter Holmes’s death, all are dependent on this. Failure to recognize the potential for extension and rapid fire progress, the influence of creating ventilation openings on Floor 2, and recognition of developing fire conditions were likely the most significant causal factor in this incident. Had this not been the case, the firefighters and officers involved would have had the opportunity to adjust their tactical operations or exit the building prior to the occurrence of the extreme fire behavior that trapped the search team.

NIOSH Report F2008-06 quotes Deputy Chief Vincent Dunn regarding flashover indicators:

There are two warning signs that may precede flashover: heat mixed with smoke and rollover. When heat mixes with smoke, it forces a fire fighter to crouch down on his hands and knees… As mentioned above, rollover presages flashover.

This statement is scientifically incorrect. Heat is simply energy in transit due to temperature difference. It is not a substance and cannot mix with anything else. Increasing temperature is an indicator of potential for flashover, but perception of a rapid increase in temperature is not certain to give adequate warning to take corrective action or escape from the hazardous situation. In addition, rollover does not always precede flashover (it is an important indicator, but only one of many).

The report also quotes Chief Dunn regarding defensive search tactics.

Three defensive search tactics are as follows:

1. At a door to a burning room that may flashover, fire fighters should check behind the door to the room and sweep the floor near the doorway. Fire fighters should not enter the room until a hose line is in position.
2. When there is a danger of flashover, fire fighters should not go beyond the “point of no return.” The point of no return is the maximum distance that a fully equipped fire fighter can crawl inside a superheated, smoke-filled room and still escape alive if a flashover occurs. The point of no return is approximately five feet inside a doorway or window.
3. When searching from a ladder tip placed at a window, look for signs of rollover if one of the panes has been broken. If rollover is present, do not go through the window. Instead, crouch below the heat and sweep the interior area below the windowsill with a tool. If a victim has collapsed there, you may be able to crouch below the heat enough to pull him to safety.

While these tactics have validity, making for search without without protection of a hoseline even to Chief Dunn’s “point of no return”� presents a significant risk. Further, I am uncertain that there is any scientific evidence supporting the concept of the point of no return as described by Chief Dunn. There are numerous examples of situations where firefighters thought they had time to complete a search, but were trapped by extremely rapid fire development. The risk of searching under marginal conditions requires firefighters to effectively read the fire and mitigate hazards in the fire environment through effective use of gas cooling and control of the ventilation profile (either tactical ventilation or anti-ventilation as appropriate) and establishing fire control in addition to primary search.

Recommendation #4: Fire departments should ensure that fire fighters conducting an interior search have a thermal imaging camera.

The thermal imaging camera is a tremendous technological innovation which can significantly speed search operations and provide visual indication of differences in thermal conditions. However, implementation of this recommendation would not necessarily have impacted on the outcome of this incident.

Recommendation #5: Fire departments should ensure ventilation is coordinated with interior fireground operations.

In the discussion of this recommendation, the NIOSH Report F2008-6 states “By eliminating smoke, heat, and gases from the fire it will help minimize flashover conditions”�

This statement is not always true. The influence of ventilation on fire development is dependent on burning regime (fuel or ventilation controlled) and the location of the inlet and exhaust openings. Heat release rate from a ventilation controlled fire will increase as ventilation is increased, potentially taking the fire to flashover (rather than the reverse as indicated by the statement in this NIOSH report). In addition, creation of an air track that channels the spread of hot gases and flames to additional fuel packages can result in fire extension and subsequent flashover. Both of these factors were likely to have been significant in this incident. Coordination of ventilation and search or ventilation and fire attack (as frequently stated in NIOSH reports related to incidents involving extreme fire behavior) requires knowledge of fire dynamics and the influence of ventilation in fire behavior.

Recommendation #6: Fire departments should ensure that Mayday protocols are developed and followed.

This recommendation is important, but fails to address other individual level survival skills that must be integrated with these procedures. For example, in this incident, the Lieutenant and Firefighter might have been able to take refuge in one of the bedrooms, closing the door to provide a barrier to hot gases and flames. A ladder was initially placed to a window in the bedroom on Side B (in close proximity to the location where Firefighter Holmes was found). Ladders were subsequently placed to the bedroom windows on Side A. While it may have been difficult to accomplish this under conditions of extreme thermal insult, if developing conditions had been recognized soon enough (see my earlier observation on situational awareness), this may have bought critical seconds and allowed the trapped search team to escape or be rescued.

Recommendation #7: Fire departments should ensure that the Incident Commander receives pertinent information during the size-up (i.e., type of structure, number of occupants in the structure, etc.) from occupants on scene and that information is relayed to crews upon arrival.

Had the Incident Commander received more specific information from the occupants or law enforcement, this may have shifted focus in search operations as survivability in the original fire unit was doubtful. Despite this, the civilian casualty was later located outside the fire unit, behind the door in the front foyer that served both dwelling units.

Recommendation #8: Fire departments should ensure that fire fighters communicate interior conditions and progress reports to the Incident Commander.

This is a key element in maintaining situational awareness (on the part of the Incident Commander). However, it is equally important for Command to communicate with interior crews regarding conditions observed from the exterior or situations (such as water supply limitations) that will impact interior operations.

Recommendation #9: Fire departments should develop, implement, and enforce written standard operating procedures (SOPs) for fireground operations.

This recommendation focuses on general good practice, but is not tied to specific contributing factors related to the injuries and fatality that resulted in this incident. This type of recommendation should likely be included, but placed in a separate section so as not to dilute the focus on lessons learned.

Recommendation #10: Fire departments and municipalities should ensure that local citizens are provided with information on fire prevention and the need to report emergency situations as soon as possible to the proper authorities.

Recommendation #11: Building owners and occupants should install smoke detectors and ensure that they are operating properly.

If implemented prior to this incident, Recommendations #10 and #11 would likely have had a positive impact on its outcome, particularly with regards to the civilian casualty and the severity of conditions encountered by the firefighters.

However, these two recommendations do not go far enough. Citizens must also recognize the need for rapid egress and the value of closing doors to confine the fire and limit inlet of air required for continued fire development and increasing heat release rate.

Detailed Case Study

CFBT-US has developed a detailed case study based on this incident and the data contained in NIOSH Report F2008-06. Download the Grove City, Pennsylvania Residential (Duplex) Fire Case Study in PDF format.

Now What?

Over the last two weeks we have spent considerable time with a NIOSH Report F2008-06. NIOSH has completed 335 investigations during the first 8 years that this program has been in existence. 49 more investigations are pending. The information contained in these reports provides a vast reservoir of data that can be used to deepen understanding of your craft and improve decision-making and risk management skills.

Make a commitment to developing your expertise as a firefighter or fire officer in the new year and for the rest of your life. Look for the this logo (more information to follow)!

Have a safe and happy new year!

Ed Hartin, MS, EFO, MIFIreE, CFO

I would like to extend my thanks to Steve Berardinelli and Tim Merinar of the NIOSH Firefighter Fatality Investigation and Prevention Program for their assistance in developing the Case Study based on NIOSH Report F2008-06. Just prior to my first post regarding this incident, I forwarded a request for additional information to the NIOSH staff and received a quick response from Tim that he would forward my request to the investigators. This morning I had an excellent conversation with Steve and obtained additional information that was extremely helpful in refining the case.

I will be revising Developing & Using Case Studies: Pennsylvania Duplex Fire Line of Duty Death (LODD) and Pennsylvania Duplex Fire: Firefighting & Firefighter Rescue Operations based on additional information provided by NIOSH. Changes include addition of information related to the ventilation profile, initial fire conditions, and occupant actions.

Analysis and Critique

It is important to note that the observations in this post regarding the contributory factors identified in NIOSH Report F2008-06 are made as a critical friend. Most firefighters and fire officers who read this (or any) NIOSH report will agree with some of the recommendations, may disagree with others, and undoubtedly would make additional recommendations based on their individual assessment of the incident. Analysis of contributing factors and recommendations (rather than simply accepting them) is an important element in the learning process. Dig a bit deeper and build an understanding of why events may have unfolded the way that they did. Identify the critical points at which the outcome could have been changed (there are likely more than one). Think about how these recommendations might apply to you and your department.

As discussed in my earlier post; Criticism Versus Critical Thinking, the intent of this analysis and critique is to share what I have learned from this case, with all due respect to those involved. The firefighters and fire officers involved in this incident were faced with a difficult situation to begin with, having an occupant reported trapped in the building. This was compounded by challenging water supply problems due to multiple frozen hydrants. It is far easier to examine incident information in a comfortable environment with no time pressure than to deal with these issues in the cold, early morning hours.

My original intent was to examine both the contributory factors and recommendations in NIOSH Report F2008-06. However, due to length, this critique will be divided into two separate posts.

A Brief Review of the Incident

On February 29, 2008 The Grove City Fire Department, Pine Township Engine Company, and East End Fire Department responded to a fire in a two-story, wood frame duplex in Grove City, Pennsylvania. Initial dispatch information and the initial size-up indicated that a female occupant was trapped in the building. When the Chief and first engine company arrived, the unit on Side D was substantially involved with smoke in the unit on Side B. Several hoselines were placed into operation for fire control, but fire conditions precluded an offensive attack in the involved unit. Pine Township Engine 85 was assigned to search and rescue of the trapped occupant. Firefighter Brad Holmes and Lieutenant Scott King were tasked with primary search of Exposure Delta. Firefighting operations were hampered by two frozen hydrants, necessitating support of initial operations using only apparatus tank water while an operable hydrant was located. During their search, water supply was interrupted and rapidly deteriorating conditions trapped the search crew. After being rescued by the Rapid Intervention Team, both members were transported to Pittsburgh’s Mercy Hospital Burn Unit. Firefighter Brad Holmes had burns over 75% of his body, and died from his injuries on March 5, 2008. Lieutenant King suffered less serious injuries and was treated and released. A 44 year old female occupant of the dwelling also died.

Figure 1. 132 Garden Avenue-Side Alpha

Note: Fire Department Photo – NIOSH Death in the Line of Duty Report F2008-06. This photo likely illustrates conditions after 0635 (approximately 19 minutes after arrival of the first fire unit, Chief 95).

Additional detail is provided in Developing & Using Case Studies: Pennsylvania Duplex Fire Line of Duty Death (LODD) and Pennsylvania Duplex Fire: Firefighting & Firefighter Rescue Operations. In addition, readers should review NIOSH Report F2008-06.

Contributory Factors

NIOSH Report F2008-06 identifies seven contributory factors in the injury of Lieutenant King and death of Firefighter Holmes. While each of these factors may have had some influence on the outcome of this incident, this analysis provides insufficient clarity and misses several key factors.

• Inadequate water supply. Two hydrants in the vicinity of the burning structure were frozen from the cold weather.
• The victim and injured Lieutenant did not have the protection of a charged hoseline during their search for the trapped occupant.
• Inadequate training in defensive search tactics.
• Non-use of a thermal imaging camera which may have allowed the search and rescue crew to advance more quickly through the structure.
• Ventilation was not coordinated with the interior search.
• Size-up information about the structure was not relayed to the interior search crew. The interior crew was searching in the wrong duplex for the trapped occupant and did not realize they were in a duplex.
• The incident commander was unaware of the search crew’s location in the building. He did not receive any interior reports and was concentrating on resolving water supply issues.

Water Supply: The lack of a continuous water supply likely influenced the loss of the structure and loss of water supply to handlines was in all probability a causal factor in the injury of Lieutenant King and death of Firefighter Holmes. However, the volume of tank water available on apparatus that arrived prior to the search team becoming trapped on Floor 2 (5000 gallons) was likely adequate to support search of the uninvolved areas of the building and confine the fire to the unit of origin for the time required to search uninvolved areas of the building. Anticipation that a continuous water supply would be established may have influenced the tactics and water application used by initial arriving companies.

Protection of the Search Team: Failure to protect the search team with a hoseline was a significant factor in this incident. However, the outcome would likely have been the same if the search team had a hoseline as fire extended from below to cut off their means of egress. A backup line should also have been in place to protect the search team’s egress while they were working above the fire. There was an additional hoseline initially deployed to the doorway on Side A, however, the position and operation of this line while the search team was on Floor 2 was not specified in the report. Without additional tactical changes, the loss of water supply would have precluded effective hoseline support of search operations.

Training in Defensive Search Tactics: Identifying a lack of training in “defensive search tactics” is too narrowly focused. The issue here is significantly broader than stated in the report and should be restated as lack of situational awareness. This causal factor fails to identify the lack of situational awareness on the part of the search crew, the incident commander, and others on the fireground to developing and potential fire conditions and water supply limitations. This lack of situational awareness is likely due to inadequate training in fire behavior and applied fire dynamics (rather than simply inadequate training in defensive search tactics).

Use of a TIC: Undoubtedly effective use of a TIC can speed search operations. However the NIOSH report indicated that visibility was not excessively compromised during the initial stages of search on both floors 1 and 2. Reducing the time required to complete the search could have been influenced by use of a TIC, by assigning a separate crew to perform fire control on Floor 1 of Exposure B and allowing Firefighter Holmes and Lieutenant King to focus on primary search or by both of these actions. While technology may useful in improving firefighter safety, it is important to not simply look for a technological solution to a problem which can be substantively related to human factors such as situational awareness, communications, and decision-making.

Tactical Ventilation: The location, sequence, and lack of coordination in ventilation was likely a causal factor (along with failure to protect the means of egress with a hoseline and loss of water supply) in the injury to Lieutenant King and death of Firefighter Holmes. Creation of exhaust openings above the fire created a clear path of travel for hot gases and flames from Floor 1 to Floor 2 via the interior stairs and increased air supply to a fire which was likely ventilation controlled (resulting in an increase in heat release rate (HRR) sufficient to result in flashover. This contributory factor also points to the need for training on the influence of tactical operations (particularly ventilation) on fire behavior.

Communication of Size-Up Information: Size-up information related to the building and possible victim location could have been a significant factor in focusing the location of the search. However, the civilian occupant was not in either unit, but was located (after fire control) behind the door in the foyer. If it was known that the trapped occupant was from the fire unit, it may have appeared that there was no savable life (due to the extent of fire involvement). But this does not preclude the assumption that she may have been confused and gone into the other unit.

Note: There is some difference of opinion between the fire investigator and operational personnel as to the likely location of the victim prior to structural collapse. It is possible that the victim died on Floor 2 of the fire unit and fell to the position where she was found due to structural collapse.

Accountability and Situation Status: Accountability and communication of situation status is critical to the safety of everyone operating on the fireground. Clear communication in advance of the loss of water supply could have influenced the outcome of this incident. When operating off tank water, it is essential to follow a similar philosophy as the Rule of Air Management and retain sufficient water to exit from the hazardous environment. However, it does not appear that the lack of accountability regarding the search team significantly delayed the rescue effort.

My next post will examine the recommendations made in NIOSH Report F-2008-06 and will provide a link to a detailed, written case study based on this incident in PDF format.

Happy Holidays,
Ed Hartin, MS, EFO, MIFireE, CFO

This post continues examination of NIOSH Death in the Line of Duty Report F2008-06. My previous post, Developing & Using Case Studies: Pennsylvania Duplex Fire Line of Duty Death (LODD) emphasized the importance of case studies to individual and organizational learning and presented initial information about the incident which resulted in injury to Lieutenant Scott King and the death of Firefighter Brad Holmes of Pine Township Engine Company.

Figure 1. 132 Garden Avenue-Side Alpha

Note: Fire Department Photo – NIOSH Death in the Line of Duty Report F2008-06. This photo likely illustrates conditions after 0635 (approximately 19 minutes after arrival of the first fire unit, Chief 95).

Firefighting Operations

Command assigned Engine 95 (officer and five firefighters) to fire suppression. They deployed a 1-3/4″� (45 mm) line to the door on Side A, but were unable to make entry due to the volume of fire in the involved unit. Engine 95 also deployed a 2-1/2″� (64 mm) handline to the A/D corner. Both lines were immediately placed into operation. NIOSH Report F2008-06 indicated that the 1-3/4″� line stretched to the door on Side A was “unable to make entry due to heavy fire conditions”�. However, exact placement and operation of the 2-1/2” handline was not specified. This line may have been used to protect Exposure D (a wood frame dwelling approximately 20′ from the fire unit), for defensive fire attack through first floor windows, or both.

Figure 2. Fire Unit and Exposure Bravo Floor 1

Note: This floor plan is based on data provided in NIOSH Report F2008-06 and is not drawn to scale. Windows shown as open are based on the narrative or photographic evidence. Door position is as shown based on information provided by NIOSH Investigator Steve Berardinelli (this differs from the NIOSH report which includes the fire investigators rough sketch showing all doors open). Windows shown as intact are not visible in the available photographs, but may be open due to fire effects or firefighting operations (particularly those in the fire unit).

Second due, Engine 95-2 performed a forward lay from a nearby hydrant and supplied Engine 95 with tank water while waiting for the supply line to be charged.

Engine 85 (chief, lieutenant, and three firefighters) was assigned to primary search and rescue of the trapped occupant. Tasked to conduct primary search in Exposure B, Firefighter Holmes and Lieutenant King were performed a 360^o reconnaissance prior to making entry. While this was being done other members of the company placed a ladder to a window on Floor 2 Side B (see Figure 3). The NIOSH Report does not specify if the search team was aware of ladder placement.

The Officer of Engine 95 vented the window on Floor 1 Side A of Exposure Bravo and observed that the ceiling light was on (indicating that there was limited optical density of the smoke on Floor 1 of the exposure). Firefighter Holmes and Lieutenant King entered through this window (see Figure 2) to conduct primary search of the exposure and observed that the temperature was low and there was limited smoke on Floor 1. Engine 95 passed the search team a 1-3/4″� (45 mm) handline through the window and the search team knocked down visible fire extension and completed their search of the first floor. At this point, Firefighter Holmes and Lieutenant King left the hoseline on Floor 1, went up the stairs to Floor 2 and began a left hand search.

Figure 3. Fire Unit and Exposure Bravo Floor 2

Note: See the prior comments regarding windows and door position.

The Officer of Engine 95 noticed that the search crew had finished their search on the first floor and were advancing to the second floor. He placed a ladder and broke the window on Floor 2, Side A (See Figure 3). He stated that there was not much heat on the second floor because the plastic insulation on the window was not melted, but he did notice heavy black smoke beginning to bank down. The NIOSH Report did not specify the depth of the hot gas layer (down from the ceiling) or the air track at the window that was vented or Floor 1 openings (windows and door).

The hydrant that Engine 95-2 laid in from was frozen as was the hydrant several houses beyond the fire buildingFirst alarm companies used tank water to support initial firefighting operations. The crew from Engine 95-2 began to hand stretch a 3″� line to a working hydrant on a nearby cross street.

After Firefighter Holmes and Lieutenant King partially completed their search of Floor 2, Lieutenant King’s air supply was at one half and Firefighter Holmes was unsure of his air status, so the Lieutenant decided to exit. At approximately the same time, Engine 95 ran out of water and the Command ordered companies to abandon the building with Engine 85 sounding its air horn as an audible signal to do so. The Accountability Officer called for a Personnel Accountability Report (PAR), but received no response from Lieutenant King or Firefighter Holmes.

Almost immediately after Engine 95 ran out of water, conditions changed rapidly decreasing visibility and increasing temperature on Floor 2 of Exposure B and fire involvement of Floors 1 and 2 of both units. With deteriorating conditions on the second floor, Lieutenant King became disoriented and separated from Firefighter Holmes. He radioed for help at 0638 hours. “Help! Help! Help! I’m trapped on the second floor!” In a second radio transmission, Lieutenant King indicated he was at a window on Side D.

Firefighter Rescue Operations

After hearing radio traffic that the search crew could not find their way out and they were by a window the Engine 95 officer accessed a window on Side B Floor 2 (using a ladder previously placed by Engine 85-2). He broke out the window to increase ventilation and attempt contact with the search team.

A crew from Engine 77 was tasked as a second search team and preparing for entry when the IC ordered companies to withdraw. However, when they heard the Lieutenant’s call for help, they immediately went to Side D, not seeing the Lieutenant at the window, they continued to Side B. The officer from Engine 77 climbed the ladder they had placed earlier to attempt contact with the initial search team. There was heavy black smoke coming from this window, but no fire. He straddled the window sill attempting to hear any movement, a PASS device, or voices. He banged on the window sill as an audible signal to the search team, but received no response. He also attempted to locate the search team using a TIC, however, it malfunctioned.

Flames now pushing out the first floor windows of both the unit originally involved in fire as well as Exposure B. Lieutenant King managed to find his way to the staircase, stumbled down the stairs and out the door on Side A. His protective clothing was severely damaged and smoldering. He collapsed in the front yard and told the other firefighters that the victim was trapped on the second floor. The RIT (R87) made entry supported by a hoseline operated from the entry point by Engine 85-2. Firefighter Holmes was located approximately 10′ (3 m) from the top of the stairs (as illustrated in Figure 3). He was semi-conscious and on his hands and knees. The RIT removed Firefighter Holmes via the stairway to Side A. Lieutenant King and Firefighter Holmes were transported to a local hospital where they were stabilized prior to transport to the Mercy Hospital’s Burn Unit in Pittsburgh.

Questions

The following questions provide a basis for examining the second segment of this case study. While limited information is provided in the case, this is similar to an actual incident in that you seldom have all of the information you want.

1. What was the stage of fire development and burning regime in the fire unit when the search team entered the exposure?
2. What Building, Smoke, Air Track, Heat, and Flame (B-SAHF) indictors can be observed in Figure 1?
3. What was the stage of fire development and burning regime in Exposure B when the search team entered?
4. What type of extreme fire behavior event occurred in the exposure, trapping Firefighter Holmes and Lieutenant King? What leads you to this conclusion?
5. What were the likely causal and contributing factors that resulted in occurrence of the extreme fire behavior that entrapped the Firefighter Holmes and Lieutenant King?
6. What self-protection actions might the search team have taken once conditions on Floor 2 of Exposure B began to become untenable?
7. What action could have been taken to reduce the potential for extreme fire behavior and maintain tenable conditions in Exposure B during primary search operations?
8. What was the tactical rate of flow for full involvement of a single unit in this building? (The tactical rate of flow is the flow required for fire control and does not include the flow rate for backup lines.)
9. What factors may have influenced the limited effectiveness of the 1-3/4” and 2-1/2” attack lines deployed by Engine 95?
10. What tactical options might have improved the effectiveness of fire control operations given the available water supply?

My next post will examine the contributing factors and recommendations made in NIOSH Death in the Line of Duty Report F2008-06 and will include a link to a more detailed written case study of this incident in PDF format.

Ed Hartin, MS, EFO, MIFireE, CFO

This post is a continuation of my feedback to the National Institute for Occupational Safety and Health that will be presented at the public stakeholder meeting conducted in Chicago, IL on 19 November 2008. My recommendations are presented in the form of an analysis of NIOSH Report F2007-29. This incident resulted in the death of Captain Kevin Williams and Firefighter Austin Cheek of the Noonday Volunteer Fire Department.

This post continues with discussion the NIOSH reports examination of the influence of ventilation in this incident and provides specific recommendations for improvement of the NIOSH Firefighter Fatality Investigation and Prevention Program.

Tactical Ventilation

The NIOSH report makes a general recommendation that “fire departments should ensure that properventilation is done to improve interior conditions and is coordinated with interior attack”� [emphasis added]. However, the report is misleading and fails to address key issues related to tactical ventilation, its effective application, and its tremendous influence fire behavior.

NIOSH Report F2007-29 indicated that positive pressure ventilation was initiated prior to the second entry by the initial attack crew (a significant difference from the information provided in the Texas State Fire Marshal’s report). However, no mention is made of any action (or lack thereof) to create an adequate exhaust opening for effective horizontal positive pressure ventilation. While advising that ventilation needs to be proper, it would be helpful to provide more specific guidance. Lack of an adequate exhaust opening prior to pressurizing the building has been a major factor in a number of incidents in which application of positive pressure resulted in extreme fire behavior such as ventilation induced flashover or backdraft. Positive Pressure Attack for Ventilation and Firefighting (Garcia, Kauffmann, & Schelble, 2006), Fire Ventilation (Svensson, 2000), and Essentials of Firefighting (IFSTA, 2008) all emphasize the importance of creating an adequate exhaust opening prior to application of positive pressure.

The NIOSH report pointed out that smoke pushed out the inlet and overrode the effects of the blower, but attributed this to the presence of an attic floor that interfered with vertical ventilation rather than the lack of an adequate exhaust opening for the initial horizontal ventilation.

The PPV fan and vertical ventilation had little effect due to an attic floor being installed. At 0231 Chief #2 had horizontally vented the window on the D side near the A/D corner.

In this incident, ventilation was being performed while the interior attack crew was already inside working. When the ventilation was completed, minimal smoke was pushed out of the vented hole but dark smoke pushed out of the front door, in spite of the fact that a PPV fan was set up at the front door. Note: The dark smoke pushing out the door indicated that the conditions were worsening and the vertical ventilation was not impacting the fire.

In addition, the report fails to note that the opening made on Side D near the AD Corner placed the attack team between the fire and an exhaust opening. As with lack of an adequate exhaust opening, this has been demonstrated to have the potential for disastrous consequences (see NIOSH Death in the Line of Duty F2004-02).

Floor Plan Illustrating the Position of Captain Williams and Firefighter Cheek

Texas State Fire Marshal’s Office Firefighter Fatality Investigation Report FY 07-02

Extreme Fire Behavior

Command ordered companies to abandon the building at 0234 hours using three air horn blasts as an audible signal. The NIOSH report indicated that heavy fire “continued to roll out the front door”� but it is unclear how soon this occurred after smoke conditions at the doorway changed.

NIOSH Report F2007-29 does not clearly identify that extreme fire behavior was a causal or even contributory factor in the deaths of Captain Williams and Firefighter Cheek. It simply states that they died as a result of smoke inhalation and thermal burns.

NIOSH Recommendations

NIOSH made six recommendations based on analysis of the incident in which Captain Williams and Firefighter Cheek lost their lives. Several of these recommendations focused on factors that may have contributed to these two LODD. These included radio communications equipment and procedures, accountability, rapid intervention, and the importance of mutual aid training. Two recommendations were more directly related to causal factors: The importance of ongoing risk assessment and use of proper and coordinated ventilation. However, these broad recommendations miss the mark in providing useful guidance in minimizing the risk of similar occurrences.

Ensure that the IC conducts a risk-versus-gain analysis prior to committing to interior operations and continue the assessment throughout the operation.

This statement is necessary but not sufficient. Size-up and risk assessment is not only the responsibility of the incident commander. All personnel on the fireground must engage in this process within the scope of their role and assignment. Understanding practical fire dynamics is critical to firefighters’ and fire officers’ ability to recognize what is happening and predict likely fire behavior and the influence of tactical operations. To effectively address this issue, NIOSH death in the line of duty reports must be explicit and detailed with regards to key fire behavior indicators observed, subsequent fire behavior phenomena, and the influence of the action or inaction of responders on fire development.

Fire departments should ensure that proper ventilation is coordinated with interior attack.

NIOSH Report 2007-29 focused on the ineffectiveness of the vertical ventilation, but failed to recognize the impact of the sequence of action (i.e. pressurization of the building and creation of exhaust openings), inadequacy of initial exhaust openings, and eventual location of exhaust openings in relation to the operating position of Captain Williams and Firefighter Cheek.

As with situational awareness, effective tactical operations are grounded in training, education, and experience. The incident commander and crews tasked with carrying out tactical ventilation must understand how these tactics influence the fire environment and fire behavior. As with size-up and risk assessment, this is dependent on an understanding of practical fire dynamics.

Other than indicating that ventilation must be coordinated with interior attack, the NIOSH report did not speak to fire control operations conducted during this incident. From the building floor plan and information presented in both the reports by NIOSH and the Texas State Fire Marshal, it appears that the fire was shielded and direct attack was not possible from the position of the first attack team nor the position reached by Captain Williams and Firefighter Cheek. The Fire Marshal’s report indicated that the initial attack team “penciled”� the ceiling to control flames overhead and experienced disruption of the hot gas layer and an increase in temperature at floor level.

Just as ventilation must be appropriate and coordinated with interior fire attack, fire control must also be appropriate and coordinated with tactical ventilation. Cooling the hot gas layer is an appropriate tactic to create a buffer zone and increase the safety of the attack team as they access a shielded fire. However, penciling (use of an intermittent application of a straight stream) the ceiling is an ineffective method of cooling the hot gas layer and results in excessive steam production. In addition, cooling the hot gas layer is not an extinguishment technique; it must be integrated with other fire control methods such as a direct attack on the seat of the fire.

NIOSH death in the line of duty reports must explicitly address the effect of tactical operations, particularly where effectiveness or ineffectiveness was a contributing or causal factor in the LODD.

The Way Forward

While this assessment has been quite critical of NIOSH’s investigation of traumatic fatalities involving extreme fire behavior, it is important to emphasize that with all its faults, the Firefighter Fatality Investigation and Prevention program is a tremendous asset to the fire service.

The following recommendations are made to further strengthen and improve the quality of this program and the utility of recommendations made to reduce the risk of firefighter line of duty deaths as a result of extreme fire behavior during structural firefighting operations:

• Emphasize the criticality of understanding fire behavior, causal factors in extreme fire behavior, and the influence of tactical operations such as fire control and ventilation.
• Increase attention to building, smoke, air track, heat, and flame indicators when investigating incidents which may have involved extreme fire behavior as a causal or contributing factor in LODD.
• Examine training in greater detail, with specific emphasis on fire behavior, situational assessment, realistic live fire training, and crew resource management.
• Provide fire behavior training to all NIOSH investigators to improve their understanding of fire development, extreme fire behavior phenomena, and the impact of tactical operations.
• Include a fire behavior specialist on the investigation team when investigating incidents that may have involved extreme fire behavior as a causal or contributing factor.
• Initiate investigations quickly to avoid degradation of the quality of information obtained from the individuals involved in the incident and other witnesses.

Ed Hartin, MS, EFO, MIFireE, CFO

References

National Institute for Occupational Safety and Health (NIOSH). (2008). Death in the line-of-duty… Report 2007-29. Retrieved November 14, 2008 from NIOSH http://www.cdc.gov/NIOSH/FIRE/reports/face200729.html.

Texas State Fire Marshal’s Office (2008). Firefighter fatality investigation FY 07-02. Retrieved November 14, 2008 from http://www.tdi.state.tx.us/reports/fire/documents/fmloddnoonday.pdf

Svensson, S. (2000). Fire ventilation. Karlstad, Sweden: Swedish Rescue Services Agency

Garcia, K., Kauffmann, R., & Schelble, R. (2006). Positive pressure attack for ventilation & firefighting. Tulsa, OK: Pen Well

International Fire Service Training Association. (2008) Essentials of Firefighting (5th ed). Stillwater, OK: Fire Protection Publications.

Public Stakeholder Meeting

On 19 November 2008, National Institute for Occupational Safety and Health (NIOSH) will conduct a public stakeholder meeting to gather input on the Firefighter Fatality Investigation and Prevention Program. This meeting has a similar focus to one held on 22 March 2006 in Washington DC. At the 2006 stakeholder meeting, NIOSH received Input from a diverse range of fire service stakeholders. Feedback was extremely supportive of the program, but provided input on potential improvements to this extremely important program. In 2006, I gave a brief presentation that focused on several key issues:

• The upward trend in the rate of firefighter fatalities due to trauma during offensive, interior firefighting operations.
• Failure of NIOSH to adequately address fire behavior and limited understanding of fire dynamics as a causal or contributing factor in these fatalities.

The issues that I raised at the 2006 stakeholder meeting continue to be a significant concern. In 2007, extreme fire behavior was a causal or contributing factor in 17 firefighter line of duty deaths (LODD) in the United States. Where these incidents were investigated by NIOSH, the investigations, subsequent reports, and recommendations did not substantively address the fire behavior phenomena involved nor did they provide recommendations focused on improving firefighters and fire officers understanding of practical fire dynamics.

Ongoing Challenges

In the 20 months since the 2006 stakeholder meeting, NIOSH has implemented a number of stakeholder recommendations. However, Death in the line of duty reports continue to lack sufficient focus on fire behavior and human factors issues contributing to traumatic fatalities during offensive, interior firefighting operations.

Where these reports could provide substantive recommendations for training and operations that would improve firefighter safety, they continue to provide general statements reflecting good practice. While the recommendations contained in NIOSH Death in the line of duty reports, are correct and critically important to safe and effective fireground operations, they frequently provide inadequate guidance and clarity.

In incidents involving extreme fire behavior, investigators frequently fail to adequately address the fire behavior phenomena involved and the implications of the action or inaction of responders. In addition, while training is addressed in terms of national consensus standards or standard state fire training curriculum, there is no investigation as to how the level of training in practical fire dynamics, fire control, and ventilation strategies and tactics may have impacted on decision making.

Presentation of these issues in general terms does not provide sufficient clarity to guide program improvement. Examination of a recent death in the line of duty report will be used to illustrate the limitations of these important investigations and reports in incidents where extreme fire behavior is involved in LODD.

Death in the line of duty… F2007-29

There are many important lessons to be learned from this incident and the limited information presented in this report. However, this analysis of Report F2007-29 focuses on fire behavior and related tactical decision-making. This analysis is completed with all due respect to the individuals and agencies involved in an effort to identify systems issues related to the identification and implementation of lessons learned from firefighter fatalities.

On August 3, 2007 Captain Kevin Williams and Firefighter Austin Cheek of the Noonday Volunteer Fire Department lost their lives while fighting a residential fire. Neither this information nor any reference to the report on Firefighter Fatality Investigation FY 07-02 released by the Texas State Fire Marshal’s Office was included in NIOSH Death in the line of duty report F2007-29. This is critical to locating additional information regarding the incident. Even more importantly, it is important to remember that firefighter LODD involve our brother and sister firefighters, not simply “Victim #1″� and “Victim #2”.

Reading the Fire

This incident involved a 2700 ft², wood frame, single family dwelling. The fire was reported at 0136 and the first unit arrived on scene at 0150. The crew of the first arriving engine deployed a 1-3/4″� (45 mm) hoseline and positive pressure fan to the door on Side A. NIOSH Report F2007-29 reported that the attack team made entry at 0151 but backed out a few minutes later due to flames overhead just inside the front door and that positive pressure was initiated at 0156 prior to the attack team re-entering the building.

However, the Texas State Fire Marshal’s Report FY 07-02 indicated the following:

Flint-Gresham Engine 1 arrived on scene at 01:50:21 positioning short of Side A� and reported, “On location, flames visible.”�

Firefighters Joshua Rawlings and Ben Barnard of the Flint-Gresham VFD pulled rack line 2, a 200� long 1.3/4” (45 mm) � line, to the front door on Side A.� Flint-Gresham VFD Firefighter Robles conducted a quick survey of the north side and then positioned the vent fan at the front door to initiate Positive Pressure Ventilation (PPV). Robles stated that the PPV was set and operating prior to entry by the first attack team. Robles stated that he started to survey the south side and noted heavy black smoke from the top half of a broken window. He stated that he reported this to the IC.

Flint-Gresham Firefighters Barnard (nozzle) and Rawlings (backup) entered through the open front door and advanced 8-10 feet on a left hand search. This attack team noted flames rolling across the ceiling moving from their left to their right as if from the attic. Rawlings stated that flames were coming out of the hallway at the ceiling area and around the corner at a lower level. Barnard reported the hottest area at the hallway. The interior attack team then backed out to the front doorway and discussed their tactics. After a brief conversation, Rawlings took the nozzle with Barnard backing him and they re-entered. They entered approximately 10 feet and encountered flames rolling from their left to their right. They used a “penciling technique”� aimed at the ceiling to cool the thermal layer. Rawlings reported in interview that there was an increase in heat and decrease in visibility as the thermal layer was disrupted and heat began to drop down on top of them.

There is an inconsistency between the NIOSH and Texas State Fire Marshal’s reports regarding the timing of the positive pressure ventilation. The NIOSH report indicates that positive pressure was applied between the first and second entries by the attack team. However, in the Fire Marshal’s report, Firefighter Robles is quoted as stating that positive pressure was applied before entry. This seems to be a minor point, but if effective, positive pressure ventilation would have significantly changed the fire behavior indicators observed from the exterior and inside the building. Recognition of this discrepancy along with a sound understanding of practical fire dynamics would have pointed to the ineffectiveness of tactical ventilation and potential for extreme fire behavior.

The NIOSH report did not identify the fire behavior indicators initially observed by Firefighter Robles or the attack team, nor did they draw any conclusions regarding the stage of fire development, burning regime (fuel or ventilation controlled), or effectiveness of the positive pressure ventilation.

NIOSH Report F2007-29 did not speak to the fact that none of the first arriving personnel verified the size and adequacy of the existing ventilation opening, the potential implications of inadequate exhaust opening size, and the need to verify that the positive pressure ventilation was effective prior to entry. In addition, the initial attack crew observed flames moving toward the point of entry, which would not be likely if the positive pressure ventilation was effective. However, no mention was made in the NIOSH report regarding conditions inside building and the observations of the attack team.

Window size is not specified, but it is likely that the opening was significantly less than the area of the inlet being pressurized by the fan. Inadequate exhaust opening area leads to excessive turbulence, mixing of hot smoke (fuel) and air, and can lead to extreme fire behavior such as vent induced flashover or backdraft. Recognition of this discrepancy along with a sound understanding of practical fire dynamics would have pointed to the ineffectiveness of tactical ventilation and potential for extreme fire behavior.

In reading this case study, it would be useful for the reader to be able to make a connection between key fire behavior indicators, the decisions made by on-scene personnel, and subsequent fire behavior. The NIOSH report did not identify the indicators initially observed by interior or exterior crews, nor did it draw any conclusions regarding the stage of fire development, burning regime (fuel or ventilation controlled), or effectiveness of the positive pressure ventilation, all of which were likely factors influencing the outcome of this incident.

NIOSH Report F2007-29 indicated that the attack team exited the building at 0213 due to low air and reported that the fire was knocked down, identified the location of a few hot spots, and that smoke conditions were light. The report follows to indicate that one of the chief officers did a walk around two minutes later and observed smoke in all the windows and smoke coming from the B/C and C/D corners of the structure. However the Texas State Fire Marshal’s Report 07-02 stated:

Firefighters Rawlings and Barnard penciled the rolling flames in the thermal layer until Rawlings’s low air alarm sounded. The Incident Commander, Captain Williams and Firefighter Cheek met Firefighters Rawlings and Barnard at the front door and a briefing occurred. Firefighters Rawlings and Barnard reported to Asst. Chief Baldauf they had the hot spots out. Rawlings stated in a later interview that they told Williams and Cheek they knocked down the fire and only overhaul was needed.

At 02:13, Captain Williams and Firefighter Cheek entered the structure as attack team 2, using the same line previously utilized by Firefighters Rawlings and Barnard.

Exterior crews from Noonday and Bullard started horizontal ventilation by breaking a window out on Side C (north side). Noonday Chief Gary Aarant performed a walk around, then reported heavy smoke from the B/C,and C/D� corners and at 02:15:51 asked if vertical ventilation had been started. Command then gave the order to begin vertical ventilation.

Understanding what occurred in this incident requires more than the cursory information provided in the NIOSH report. Developing the understanding of critical fire behavior indicators is essential to situational awareness. Discussion of fire behavior indicators and their significance in NIOSH reports would provide an excellent learning opportunity. For example, in this incident, the difference between “smoke” as described in the NIOSH report and “heavy smoke” as reported in the Texas State Fire Marshal’s report is likely a significant difference in assessment of conditions from the exterior of the building (particularly if this is a change in conditions).

NIOSH Report F2007-29 made brief mention of smoke discharge from the point of entry which was being used as the inlet for application of positive pressure. “At 0236 hours, heavier and darker smoke began pushing out of the entire front door opening and overriding the PPV fan”. However, the report does not speak to the significance of this indicator of impending extreme fire behavior.

The Texas State Fire Marshal’s Report 07-02 included a series of photographs provided by the Bullard Fire Department which provided a dramatic illustration of these key smoke and air track indicators. Inclusion of these photographs in the NIOSH report would have aided the reader in recognizing this key indicator of ineffective tactical ventilation and imminent potential for extreme fire behavior.

Photo of Conditions on Side A at 0210

Bullard Fire Department Photo/Texas State Fire Marshal’s Report

Photo of Conditions on Side A at 0217

Bullard Fire Department Photo/Texas State Fire Marshal’s Report

Photo of Conditions on Side A at 0223

Bullard Fire Department Photo/Texas State Fire Marshal’s Report

NIOSH Report F2007-29 addresses the need for the incident commander to conduct a risk versus gain analysis prior to and during interior operations. However, the report does not address the foundational skill of being able to read fire and predict likely fire behavior as a part of that process. In addition, reading the fire and dynamic risk assessment are not solely the responsibility of the incident commander. Everyone on the fireground must be involved in this process within the scope of their role and work assignment. For example, the initial and subsequent attack teams were in a position to observe critical indicators that were not visible from the exterior.

While there is no way to tell, it is likely that if Captain Williams and Firefighter Cheek recognized the imminent probability of extreme fire behavior or the significance of changing conditions they would have withdrawn the short distance from their operating position to the exterior of the building. Likewise, if the incident commander or others operating on the exterior recognized deteriorating conditions earlier in the incident it is likely that they would have taken action sooner to withdraw the crew working on the interior.

Understanding practical fire dynamics, recognition of key indicators and predicting likely fire behavior is a critical element in situational awareness and dynamic risk assessment. Fire behavior and fire dynamics receive limited focus in most standard fire training curricula. It is important that NIOSH examine this issue when extreme fire behavior is a causal or contributing factor in LODD.

My next post will continue with the analysis of NIOSH Report F2007-29 and will make specific recommendations for program improvement.

Ed Hartin, MS, EFO, MIFireE, CFO

I recently read an article in the October issue ofFire Engineering magazine titled Improving Preconnect Function and Operation. The author, LT Bob Shovald, described how his department approached the process of improving operations with small, preconnected handlines and focused on three critical factors in effective engine company operations: 1) Hose diameter and flow rate, 2) nozzle selection, and 3) hoseloads. LT Shovald made a number of good points, but misconnected on the basic science behind effective and efficient use of water for fire control.

Flow Rate

LT Shovald makes a case for high flow handlines based on changes in the built environment that influence potential fire behavior.

Primarily it comes down to one important factor, gallons per minute (gpm). Using 95- and 125-gpm attack lines is outdated and dangerous.

• Because of the huge increase of synthetic materials in modern homes and businesses, including foams, plastics, vinyl, and volatile coatings, we are now experiencing fires with higher rates of release than ever before.
• Because of the high cost of energy, more homes and businesses have improved insulation. In a fire, this seals that increased heat inside the structure.
• As a result of more effective fire prevention programs, we arrive on-scene much sooner than in years past, in large part thanks to inexpensive smoke detectors.

What this adds up to is that we are getting on-scene sooner to hotter, more aggressive fires, often just before flashover conditions or self-ventilation. To fight the beast, today we need a bigger gun with bigger bullets (i.e., proving the greater gpm and thus more water faster at the start of our interior attacks). The gpm not the pressure and not the steam kill the beast.

LT Shovald’s argument for high flow handlines sounds reasonable. However, there are a few problems once you look past the surface.

Fire Power vs. Firefighting Power

LT Shovald correctly makes the connection between heat release rate and flow rate necessary for fire control. All too often, firefighters think that it takes “gpm to overcome Btu”�. However, British thermal units (Btu) like Joules (J), are a measure of energy, not its release rate. Heat release rate is expressed in units of energy per unit of time, such as Btu/minute or watts (J/s).

Heat release rate is the most critical factor compartment fire development. If heat release rate is insufficient (e.g., a small fire in a metal trash can) the fire will not flashover or reach the fully developed stage. On the other hand, if the fire involves a recliner or couch, heat release rate is likely to be sufficient for the fire to grow and rapidly transition through flashover to the fully developed stage.

However, there is another critical factor in this scenario. Oxygen is required for the fire to release the chemical potential energy in the fuel. If doors are closed and windows are intact, the fire may quickly consume much of the available oxygen. If this occurs, heat release rate is limited by ventilation and fire growth slows.

LT Shovald states that “it’s the gpm,� not the pressure, and not the steam” that extinguishes the fire. Flow rate is critical, but this is not entirely correct. Water is an excellent extinguishing agent because it has a high specific heat (energy required to raise its temperature) and high latent heat of vaporization (energy required to change it from water to steam). Of these two factors, conversion of water to steam is most significant as it absorbs 7.5 times more energy than heating water from 20^o C ( 68^o F) to its boiling point. The firefighters power is not simply related to flow rate, but flow rate effectively applied to transfer heat from hot gases and surfaces by changing its phase from liquid (water) to gas (steam). Extinguishing a compartment fire generally involves converting a sufficient flow (gpm or lpm) of water to steam. So while the “steam”� itself does not generally extinguish the fire, the energy absorbed in turning the water to steam has the greatest impact on fire extinguishment.

Changes in the Built Environment

LT Shovald is correct that many of the synthetic fuels used in today’s buildings have a higher heat of combustion (potential chemical energy) and given sufficient ventilation have a higher heat release rate when compared to materials such as wood and paper. True to their design, modern, energy efficient buildings retain energy during fire development, speeding the process. However, this type of building also controls normal ventilation (the building is not as “leaky” as older structures) and energy efficient windows are far less likely to fail and change the ventilation profile. As a consequence, the fire department is likely to encounter ventilation controlled fires where heat release rate is limited by the available oxygen. Early detection may also influence fire conditions as firefighters may arrive to find a pre-flashover growth stage fire when heat release has not yet peaked.

The key here is that flow rate must be sufficient to meet or exceed the fires heat release rate. Arriving earlier in the fires growth and building characteristics leading to a ventilation controlled fire, do not necessarily lead to the need for a higher flow rate, on the contrary, the required flow rate during the growth stage is actually lower than that for a fully developed fire (when heat release rate is at its maximum). However, firefighters must also consider potential increase in heat release rate that result from tactical ventilation or unplanned changes in the ventilation profile (e.g., failure of a window).

One excellent point in supporting the argument for high flow handlines that LT Shovald did not raise is the large volume (floor area and ceiling height) and limited compartmentation encountered in many contemporary homes. Older homes generally had smaller rooms and were more highly compartmented. Many new homes have spacious and open floor plans, in some cases with multi-level atriums and high ceilings. In addition to frequently having open floor plans, many of these buildings are also have an extremely large floor area. This type of structure presents a significantly different fire problem and often requires a much higher flow rate than a more traditional, highly compartmented residence.

Tactical Flow Rate

While I agree with LT Shovald regarding the value of high flow handlines, his statement that 95 and 125 gpm are “outdated and dangerous” is unsupported. Safe, effective and efficient fire control requires:

• Water application to control the fire environment as well as direct attack on the fire
• Appropriate flow rate for the tactical application (cooling hot, but unignited gases may be accomplished at a lower flow rate than direct attack on the fire)
• Direct attack to exceed the critical flow rate based on the fires heat release rate
• Sufficient reserve (flow rate) be available to control potential increases in heat release rate that may result from changes in ventilation
• Water application in a form appropriate to cool its intended target (i.e., small droplets to cool hot gases or to cover hot surfaces with a thin film of water).
• Water to reach its intended target (fog stream to place water into the hot gas layer and a straight or solid stream to pass through hot gases and flames and reach hot surfaces)
• Control of the fire without excessive use of water

A flow rate of 95 or 125 gpm is only dangerous if firefighters attempt to use it to control a fire which requires (or has the potential to require) a higher flow rate. While a high flow rate will quickly extinguish a small fire, this generally results in use of considerably more water as illustrated below.

Effective and efficient fire control requires that we match the flow rate to the task at hand. At the simplest level this means using 1 �”� (38 mm) or 1 �”� (45 mm) handlines for smaller fires and 2″� (50 mm) or 2 �”� (64 mm) handlines for larger fires. It may also mean placing control of flow rate in the nozzle operators hands by using a variable flow or automatic nozzle and letting the firefighter select the flow rate based on the tactical situation.

Ed Hartin, MS, EFO, MIFireE, CFO