The following is from a letter sent to Editor in Chief Robert Halton from Oklahoma Senator Tom A. Coburn, M.D.:
Thank you for following up with me. I appreciate hearing from you after we spoke in the Chicago airport, and I am glad to have the Human Events article. I deeply apologize for the delay in my response.
As you may know, S. 3267, the Fire Grants Reauthorization Act of 2010, which is referenced in the Human Events article, would authorize $950 billion for the U.S. Fire Administration (USFA), to aid in preventing and responding to fires and other related hazards by awarding grants to fire departments and state training institutions to train personnel, modify facilities, and purchase equipment related to firefighting.
I oppose S. 3267 because I do not believe it is the responsibility of the federal government to provide funding for fire services to local fire departments. States and local municipalities should bear the lion’s share of supporting their firefighters. In addition to this belief, S. 3267 would make several changes to the fire grant program, of which I have serious concerns.
The bill would change the grants from competitive to guaranteed percentages. By changing from competitive funding to guaranteed funding, the bill reinforces the federalization of our fire departments. It also lowers matching fund requirements for state and local governments. It is my opinion that these changes encourage state and local governments to supplant their funding on behalf of “guaranteed” funding.
Finally, the bill would allow for waivers to eliminate matching requirements. States should have to have some skin in the game, especially given the fact that this is primarily a state and local responsibility.
I believe it is also important to note that the federal government recently contributed $810 million for fire assistance programs through the Department of Homeland Security fiscal year 2010 appropriations bill (P.L. 111-83). Moreover, the 2009 “stimulus bill,” the American Recovery and Reinvestment Act (ARRA, P.L 111-5) of 2009, provided $210 million for fire assistance programs.
Our forefathers understood that the only way to preserve freedom for future generations was to limit federal authority. They understood the tendency for governments to seize increasing power, and they created protections for posterity by enacting the United States Constitution. Unfortunately, Congress and our nation’s leaders are turning a blind eye to the unsustainable level of government spending that is threatening the long-term viability of the American economy. Given the enormous $13.8 trillion deficit our country is facing, I believe Congress should support the ideals that built the most prosperous economy in history: freedom, individual liberty, competition, and hard work.
Nozzle flow rate and stream
This is in regard to “A Quantitative Approach to Selecting Nozzle Flow Rate and Stream, Part 1,” by Jason N. Vestal and Eric A. Bridge (Fire Engineering, October 2010).
I have been reading and learning from Fire Engineering articles since the mid-1960s. Only once before have I been in as much disagreement with an article as I am with this one. Although I have several issues with this article, I will for the sake of brevity respond only to those issues I consider most critical.
First, the overall belief that drives this article, that fires today burn hotter because of plastics and synthetics, is incorrect. It is correct that plastics and synthetics contain more thermal energy, but it is also a fact that they need proportionally more oxygen to release it. This is a well-documented fact that goes back to the article “The Relation of Oxygen to the Heat of Combustion of Organic Compounds,” written in 1917 by W.M. Thornton, D.Sc., D.Eng. Dr. Thornton explains that it is the amount of oxygen available for combustion (not what is burning) that determines the energy (heat) release rate of organic compounds. Today, this is referred to as “Thornton’s Rule.”
In the 1970s, Clayton Huggett, a fire researcher at the National Institute of Standards and Technology (NIST), then the National Bureau of Standards, quantified Thornton’s Rule. Huggett’s research showed that within a small margin of difference, ± 5%, all common hydrocarbons release 13.1 kJgO2 (kilojoules per gram of oxygen). These findings were detailed in his article “Estimation of Rate of Heat Release by Oxygen Consumption Measurements.” His findings verified that oxygen is the primary factor in determining heat-release rates, giving substance to Thornton’s Rule beyond doubt. And, since for all practical purposes, all compartment fires are ventilation limited, the heat release rate for a room circa 2010 vs. 1950 or even 1910 will be the same. Even after a compartment has been ventilated, typical rooms still will not have enough oxygen for a fire to transition from a ventilated-limited to fuel-limited state.
The second item I found significant issue with is the characterization of the findings of the research of Keith Royer and Floyd Nelson at Iowa State University. The authors characterize the Iowa Rate-of-Flow Formula as “… based on the volume (L × W × H divided by 100) of the largest single noncompartmentalized room, with no interior life hazard in which multiple 30° fog lines were used simultaneously to indirectly attack the fire for 30 seconds.” This is not what Royer and Nelson concluded. Iowa State University, Engineering Extension Service, Bulletin No. 18 clearly details the findings of Royer and Nelson based on experiments they conducted from 1952 to 1959.
According to Bulletin No. 18, the Iowa Rate-of-Flow Formula is based on two separate facts: “(1) The study of expansion ratios of water to steam indicates that one gallon of water will produce, with a margin of safety, 200 cubic feet of steam, and (2) The study of heat production in relation to oxygen also indicates that in the conversion of water to steam, one gallon of water will absorb, with a margin of safety, all of the heat that can be produced with the oxygen available in 200 cubic feet of normal air.” Also found in Bulletin No. 18 is the following statement: “The amount of oxygen available to a fire governs the heat that can be produced with ordinary fuels, regardless of their nature.” These statements, quoted from Bulletin No. 18, are examples of the presence of Thorton’s Rule and are the heart and soul of the Iowa Rate of Flow Formula.
Bulletin No. 18 also explains in detail the recommended application of the water, developed as a result of their experiments: “It is known from proven experiments that the previously mentioned results are accomplished by the clockwise rotation of the nozzle. This rotation should be made following the contour of the area, striking as much of the perimeter as possible with the outer surface of the fog stream.” As for the pattern, “The fog pattern is adjusted so it will just reach across the area involved.” Keith Royer and Floyd Nelson had developed the combination attack, not the indirect attack incorrectly detailed in this article.
Finally, I do not find the explanation of how only two 15⁄16-inch tips at 50 psi meet the flow rate of NFPA 1710 useful. It would be virtually impossible to depict every combination of kinks that could restrict the flow of water in a handline. For the authors to factor in their favorite kinks to justify their theory is less than scientific. In reality, they should be training their firefighters that kinks are unacceptable and to make every effort to prevent them in the first place. It is possible to prevent kinks, which allows for a greater selection of nozzles and flows. Kinks in hose are something we can prevent and should not be tolerated, let alone factored into fire-flow calculations.
The point I am trying to make is that firefighting is a science. Fires burn and heat behaves according to the laws of chemistry and physics, yet most firefighters never get exposed to either science. It’s time we changed that so we can better understand how fires behave and, more importantly, why they behave that way.
William F. Crapo
Deputy Chief (Ret.)
Harrisonburg, Virginia
Jason N. Vestal and Eric A. Bridge respond: Since this is a two-part article, we preface our response with the comment that we will limit a majority of our discussion to those issues raised by Chief Crapo that pertain to Part 1. Some of the questions or concerns he posed are covered in more depth in Part 2. (Editor’s note: Part 2 was published in the January 2011 issue.)
The Random House Dictionary defines science as the systematic study of the physical and material world gained through observation and experimentation. In our work published in the October 2010 article, we approached the solution to the problem stated in the introduction following the scientific method. This included stating the problem [what is the best gallons-per-minute (gpm) value in the context presented?]; presenting and reviewing our research and the research of many others over many years; presenting observations of practical experience; interpreting the results; and presenting a conclusion. Part 1 included 23 references of traditional and contemporary research and writings over the past 60 years, including not just scientific- and engineering-based research from the United States but from abroad as well, namely Europe and New Zealand. Part 2 includes additional research references.
The third paragraph of the October article states that the flow rate and stream analysis are based on a direct, interior attack that can protect interior firefighters and trapped occupants without the benefit of structural personal protective equipment (PPE) without causing further injury. This initial attack with a single line many times is made prior to establishing ventilation to exhaust combustion products and steam. We believe that this is the operational philosophy of the vast majority in the fire service when a single engine company arrives at the scene of a working residential structure fire with known or suspected trapped occupants. To be more specific, in this scenario, firefighters are rapidly advancing to place this first fire stream between occupants and the fire; subsequent lines are then advanced to complete any remaining extinguishment.
Bulletin 18 discusses the required PPE (to implement the tactics discussed in the Iowa Rate of Flow Formula): “to place the nozzle inside the area … inside the window, or other opening at arm’s length … the nozzleman must have gloves, helmet, and protective coat.” This method of attack is more appropriate to a defensive exterior attack in which the building and anything inside have been written off as a result of risk analysis and survivability profiling.
Later in Bulletin 18, the limited availability of self-contained breathing apparatus (SCBA) or “masks,” is discussed, again contrasting interior fire attack methods of the 1950s with those of modern times. Clearly, significant changes to PPE and the widespread availability of SCBA and thermal imaging cameras have occurred since Bulletin 18 was published; these developments have dramatically changed our approach to interior fire attack and search operations. Following are our comments on some of the questions raised by Chief Crapo:
- “The overall belief that drives this entire article, that fires today burn hotter because of plastics and synthetics, is incorrect.” The Heat Release Rate (HRR) (the amount of heat released by a fire per unit of time) is the contemporary standard for measuring the intensity of fires. On pages 58-62 of Part 1 of our article, we present research conducted by the United States Park Service in 1985. This research clearly showed that as the fuel load increased, the maximum HRR increased under the same burning conditions. Comparatively, based on results conducted by the National Institute of Standards and Technology (NIST) in 2003-2004 and its wind-driven research in 2009, the maximum HRR was higher with only one more pound of fuel loading per square foot vs. the 1985 research. This is supported by Captain Stephen Marsar in “Survivability Profiling: How Long Can Victims Survive in a Fire?” (Fire Engineering, July 2010). Marsar quotes Rob Schnepp, assistant chief of the Alameda County (CA) Fire Department and president of the Cyanide Poisoning Treatment Center: “Today’s fires burn hotter, grow faster, and are more toxic than fires of the past” (“Toxic Twins” DVD series).
We are not suggesting or implying that all fuels will burn to 100-percent completion or yield their maximum possible HRR. We are only restating the observations from real-world experience that residential fires have more than enough oxygen available to readily flash in a short time and can, based on numerous variables, produce a wide range of HRRs. We are presenting an approach to deal with the worst-case scenario of maximum possible heat production in very short time frames during an interior attack.
To be fair, in contrasting the results of the 1985 tests, we did not use HRR data from the 2009 NIST test that included the addition of wind to the fire; however, when wind was added, the maximum HRR of the same room and fuel load increased even more, up to 20 MW. It is clear that as the fuel load increases, the HRR potential increases, produces more radiant heat, increases the danger to interior firefighters and trapped occupants, and increases the likelihood of flashover or rapid fire progression.
This is further exacerbated when additional oxygen is made available to the interior fire—for example, from wind, window failure, or air flow provided by fog streams. Additionally, wind events are regularly encountered in the real world, which was the basis of the 2009 NIST wind-driven fire research.
The statement “For all practical purposes, all fires are ventilation limited” is out of the context of this article, since we are presenting the scenario in which firefighters are making a direct interior attack on a fire that is still proceeding at a rate that is not ventilation limited as it is about to or has transitioned into flashover, where the growth rate is not limited by the availability of oxygen, which may be caused by open or broken windows, open doors, burn-through, or wind. When we attack building fires, we open them up; we do not close them up! Furthermore, the chemical composition of building materials and contents has changed dramatically from 1910, to 1950, to the present. This difference in chemical composition results in different surface burning rates and dramatically different fire gases being produced in different concentrations, such as carbon monoxide and numerous flammable and combustible hydrocarbon compounds. Accordingly, NIST states that this “smoke is fuel.” This has been widely reported, experienced, studied, and discussed in the fire science community, trade publications, and various texts for several years now.
The Underwriters Laboratories (UL) report “Impact of Ventilation on Fire Behavior in Legacy and Contemporary Residential Construction” clearly shows that modern synthetic furnishings burn faster, reach flashover much faster, and produce higher maximum temperatures than those fires in rooms containing older “legacy.” The UL report also states that while structure fires are ventilation limited, at all times there is an overabundance of fuel available to burn, so as firefighters force entry, open doors, and ventilate a building, a fire will increase in severity from when they first arrived as they make entry, if the correct flow rate is not applied quickly enough. As stated on page 309 of the UL report:
- The increased use of synthetic materials in the home has created faster flashover times. The two experiments demonstrated flashover times of less than 4 minutes with modern furnishings as compared to more than 29 minutes with legacy furnishings. This difference has a substantial impact on occupant and firefighter safety.
• The second item I found significant issue with is the inaccurate characterization of the findings of the research of Keith Royer and Floyd Nelson at Iowa State University.
The research and findings of Royer and Nelson, reported in Bulletin 18, were cutting edge at the time and certainly provided invaluable information that furthered the discipline of fire science and fire behavior. However, within Bulletin 18, it is very clear that the Iowa Rate of Flow Formula clearly based its primary mechanism of extinguishing interior structure fires by oxygen exclusion, through exterior applied fog streams, to produce the maximum amount of steam possible, to produce a “steam blanket” over the interior fuels. This is stated throughout Bulletin 18. The recently released full-scale UL fire research in December 2010 also showed that a fog stream is more effective than a straight stream at generating steam and pushing steam (and other products of combustion) down-range from the nozzle.
Also, nowhere within the 32-page Iowa State Bulletin is any reference made to the dangers of such steam production to trapped occupants in need of rescue, nor is there any mention of concurrent search and rescue operations or personnel searching for victims opposite the hose streams generating high volumes of steam. The only clearly stated objective for firefighters following “blacking out” of the interior fire is to make entry to conduct overhaul operations for final extinguishment. This is also the assessment presented by David Fornell in Fire Stream Management Handbook (Fire Engineering, 1991) and also by Edward Burns, retired assistant chief of the Los Angeles City (CA) Fire Department, and Burton W. Phelps, retired deputy chief of the Anne Arundell County (MD) Fire Department in National Fire Academy precourse work assignments as well as in their article “Redefining Needed Fire Flow for Structural Firefighting” (The Engine Company, Fire Engineering, November 1994).
The temperature conditions presented in the context of our article, just prior to or at flashover conditions, is in excess of 1,000°F. When a stream is applied to the upper-room levels at the ceiling, the expansion of one gallon of water applied as a fog stream at 1,000°F would be 400 cubic feet. However, Chief Crapo stated that at 212°F, a stream would expand to 200 cubic feet; interior attack temperatures prior to flashover at ceiling level are much greater than 212°F. We are most concerned with stopping fire gas production and heat production at the 1,000°F region to stop the flashover process. The expansion ratio at 1,000°F at ceiling level is not 1,700:1; it is much greater. In fact, Paul Grimwood reported it to be 3,900:1 (www.firetactics.com). Such steam production made from an interior position generates explosive steam production. As will be shown in Part 2, the size of droplets applied at this 1,000°F region has a profound effect on overall heat absorption and flaming surface cooling at this region.
In Marsar’s July 2010 article, he presents results from clinical post mortems of fire victims that were conducted over several years. The first study Marsar references is “Respiratory Burns: A Correlation of Clinical and Laboratory Results,” published in the Annals of Surgery (Emory University, 1967), In this study, 24 fatalities were examined; 18 of the fatalities were directly attributed to respiratory burns, not thermal burns. The principal causal factors included heat, toxic smoke, and humidity. Also noteworthy is that “60 percent of the victims were found to have been exposed to heat and humidity for six to seven minutes and the fatality rate increased to 90 percent for those exposed to toxic smoke for only several minutes.” The exposure time for all 24 fatalities was less than 10 minutes. The researchers also concluded that “thermal injury takes place quickly, with death occurring at temperatures of 350°F within three minutes.”
The second clinical work referenced by Marsar, “Theoretical Evaluation of Burns to the Human Respiratory Tract Due to the Inhalation of Hot Gases During the Early Stages of Fire” (Burns, 2005), contains this statement by the National Fire Protection Association: “The upper human limit of human temperature tenability is 212°F, well below temperatures found in most significant structure fires that are beyond the growth stage … temperatures higher than 500°F can be easily obtained within three to four minutes.”
Marsar’s article also reports that “lethal first-degree respiratory burns were found to occur in just 230 seconds.” Marsar suggests that with “average response times of four to six minutes in some instances where there are civilians trapped, we may only have an additional two to four minutes to search, locate, remove and revive” the victims. Considering the results of this clinical research, first- and second-due arrival times and spacing and the function of the first handline, time is of the essence to locate any trapped occupants. The stream type must not exacerbate the environment of the victims. As such, when attempting to reach trapped victims in structure fires, you must select streams that do not push additional heat, toxic gases, and humidity (steam) toward victims.
For an interior attack to successfully locate and rescue trapped occupants, we must select a stream that does not worsen temperature and toxic gas conditions. In reviewing the results from the 2009 NIST wind-driven fire research, at 360 seconds after the fires were started, directing a 80-gpm fog stream at a 30° pattern through a bedroom window dramatically increased temperatures down-range of the stream in the living room, whereas a 15⁄16-inch solid stream directed at the ceiling through the same bedroom window immediately decreased down-range living room temperatures where savable victims may be located.
Also, in the first 10 minutes of the fires, comparing the results of the two stream types and flow rates, CO and total hydrocarbon (smoke) concentrations in the living room were the same, if not slightly lower, when the solid stream was used, as opposed to the 30° fog pattern in the window. If nothing else, it can be extrapolated that for a short time period in down-range locations from the origin of the fire, even narrow 30° fog streams can increase temperatures where savable victims may be located, as opposedto applying a solid stream to the ceiling at 160 gpm from the same window, which immediately and dramatically reduced temperatures at the same location.
The UL report provides evidence that firefighter untenability is rapidly approached when ventilation is provided without applying water to the fire. The time frame reported is 100 to 200 seconds from time of ventilation to firefighter untenability. Most importantly, UL reports that with many of its experimental fires, “the time from the beginning of temperature escalation until untenability was less than 10 seconds; this provides little warning that the fire is going to flashover.” Clearly, in an advanced interior position with minimal to zero visibility, 10 seconds is not enough time to recognize an impending flashover and formulate and execute an effective escape. A stream (of the appropriate flow rate and type) must be instantly applied to the upper regions of the room that can instantly interrupt the flashover sequence while also not making matters worse for any occupants or firefighters in other parts of the structure.
Bulletin 18 also states that this will help push steam into remote areas of the fire building to control the fire in these remote areas. Steam will without a doubt exclude oxygen from a fire; however, pushing flames, steam, and other products of combustion down-range of the nozzle can also spread fire and high-temperature steam, smoke, and other acutely toxic fire gases such as CO and hydrogen cyanide toward uninvolved areas of the building, burn and kill trapped occupants, and injure or kill firefighting personnel conducting vent-enter-search operations simultaneously in areas of the building opposite the stream. Additionally, Royer and Nelson state that in buildings with false ceilings or multiple floors, this method of fire attack, if not performed correctly, can “cause loss of the entire building.”
Again, Bulletin 18 makes no reference to the life safety implications of pushing steam throughout a building. When making an interior direct or combination attack, even if a fog stream was used at an interior position, in limited- or zero-visibility conditions, it would be difficult at best to precisely adjust the fog stream to a pattern that would “just reach across the area involved.” Yet again, the recommendations found in Bulletin 18 are based on an exterior fog stream attack from an opening in the building, where time and visibility enable the precise recommended pattern adjustments to be made. Although at some point in rotating the nozzle, a combination attack will be produced as some water hits the fuel surfaces, the main objective as presented by Royer and Nelson is to generate enough steam to exclude oxygen throughout the building, not to extinguish the fire by cooling the flaming fuel surfaces. It is also clearly stated in Bulletin 18 that prompt entry will be needed for “overhaul” to extinguish hidden pockets of fire not fully extinguished by the steam produced.
• The approach taken to identify single line flow rates and the impact of kinks. We agree that at all times kinks must be prevented, minimized, and removed, and we are staunch advocates of such discipline. However, we must consider the context and operational framework of our article in that when the first-arriving engine company makes an initial interior attack, limited personnel and real-world fireground complications, such as cars in the front yard, limited access, gates, doors, front porches, etc., are involved, and lines can and do become kinked, even with the most diligent and disciplined engine company. On the interior of structures, narrow hallways, furniture, sharp turns, and falling contents and debris often cause kinks that may not be immediately recognized by interior crews advancing in limited- or zero-visibility conditions.
Like any well-engineered system, selecting a flow rate that can resist the impact of commonly encountered kinks adds redundancy to the fire attack system and increases safety. As a profession, we have a responsibility whenever possible and practical to design safety factors into our fire attack system to minimize the effect of accidents or other unforeseen complications to increase firefighter safety and occupant survival. Furthermore, the kinks selected for flow rate analysis were chosen because they are commonly encountered kinks on the fireground and as a standard of comparison against previous kink research conducted by Leihbacher, Knapp, Pillsworth, and Flatley (“How Kinks Affect Your Fire Attack System,” Fire Engineering, October 2007). These authors have many years of firefighting experience and engineering knowledge. Producing results similar to theirs provides credibility to the research through demonstrated repeatability.
Regarding the selected flow rate of 180 gpm using a 50-psi smooth bore 15⁄16-inch nozzle, this flow rate is recommended based on its ability to maintain industry standard flows for residential interior attack operations and resist the negative effects, in the most efficient manner possible, to minimize the nozzle reaction experienced by the nozzle operator while maximizing flow.
We appreciate and respect the enormous contributions of Royer and Nelson and other researchers of that time period. Without a doubt, their breakthrough research helped advance the knowledge and understanding of fire behavior in many ways. However, many advances in fire science have been made in the 50 years since Bulletin 18 was published, as there have been exponential advances in PPE engineering and the widespread availability of SCBA for use in interior attack operations. As a result, the practice (and success) of coordinating early and aggressive interior search operations with a simultaneous interior attack has evolved and continues as we speak.
Part 2 continues the quantitative, comprehensive, and scientific approach to selecting a single handline flow rate and stream type for interior attack operations with known or suspected trapped occupants when interior fire conditions are near or at flashover conditions. Included in this comprehensive and dynamic approach to stream selection is the scientific analysis of radiant heat, stream and flow rate effectiveness at various droplet sizes, and flashover dynamics in relation to stream type and flow rate.
Editor’s note: In “Industrial Strength Equipment for Industrial Strength Operations” (February 2011), author Craig Shelley mentions aqueous film-forming foam (AFFF). Although AFFF is effective in combating hydrocarbon fires, it is ineffective on alcohol or polar solvent fires. Therefore, with the prominence of ethanol on our highways and rail lines, fire departments should carry an alcohol-resistant (AR) foam. The article was written using AR-AFFF as the basis for the foam calculations. AR-AFFF is a versatile foam that can be used on hydrocarbons, alcohols, and polar solvents. Remember to consult the manufacturer’s specifications and recommendations for the correct application rates.
