Unwanted Fires Research Articles

A History of Fire Testing: Past, Present, and Future

Abstract This paper discusses the breakthroughs in science and engineering that have brought fire testing technology to its current state of maturity and provides insight into the possibilities for future fire test development by highlighting some areas where advancements are needed. The quest for understanding the properties of fire has been a part of the human experience since the first primitive human viewed the glow of a flame potentially 2.5 million years ago, during the Paleolithic Period. Since these early observations, humankind slowly developed the knowledge to use and understand fire. However, the initial revolution in fire testing did not begin until recently, in the 19th century, when the basic tools were developed that allowed for remote measurement of temperatures and heat flow. Discoveries such as the “thermoelectric effect” and the development of the First Law of Thermodynamics led to the creation of tools for calorimetry providing for the measurement of temperatures and heat flux. The second revolution in measuring and understanding fire occurred in the early 20th century with worldwide recognition that scientifically based fire standards were needed to protect life and property. At the same time, engineering innovation developed electromechanical equipment that could automatically record data measured from fire experiments. This advancement in data recording allowed for the detailed study of measured fire behavior. The third revolution in fire testing (measurement technology) occurred in the last half of the 20th century with the development of affordable digital data logging equipment and computers that enhanced data analysis and the development of scientifically based predictive models. Widespread use of technology and computational methods have opened the theoretical world which provides insight into the subtle features of fire dynamics and provides a means for developing a greater understanding of fire test method performance. Fire measurement technology now has the scientific and computational tools to make significant advancements in the development of fire safety standards. Use of these tools has directed attention to improvements needed in testing for structural fire endurance to enhance fire resistant structural designs. This would include, but not be limited to, advancements in testing of structural components, assemblies, and systems under realistic simulations of fire and load conditions. The objective for these new tests would be to enhance structural performance so that uncontrolled building fires result in burnout without partial or total collapse. Additionally, these fire measurement technologies would also lead to improvements in ignition resistant materials, surface flammability, fire growth, smoke, and toxic gas production that will save lives and reduce the high cost of unwanted fires.

Overview of some radiative transfer issues in simulation of unwanted fires

Fire is an extremely complex phenomenon that is responsible for loss of human life and considerable property and environmental damages every year around the world. Significant progress during the last few decades in modeling of pool, compartment (enclosure), urban and outdoor (i.e., forest and woodland) fires has manifested in improved understanding of fire phenomenology, fire-safety regulations and fire-fighting techniques. Recent research efforts to develop numerical CFD (computational fluid dynamics) models for simulating fire phenomena from first principles are discussed. Since both thermal and oxygen-limited feedback processes can affect fire dynamics, quantitative description of fire development requires understanding of materials, turbulence, chemical kinetics, heat and mass transfer, radiation, and other important physical processes. Focus in the discussion is on radiative transfer (one of the most complex and time consuming process) in numerical simulation of large pool, compartment, urban and outdoor fires. The overview discusses current trends and identifies the outstanding problems requiring research attention.

Underlying cause of fire: Different form of land tenure conflicts in Sumatra

One of the social phenomena that have arisen in Indonesia in the post-Reformasi period (mid-1998) is the increase in land tenure conflicts between local communities and tree plantation companies, and between local communities and the forestry department. Land tenure conflicts often trigger forest and land fires, which is both a symptom and a cause of increasing conflict over tenure and use rights. If the tenure issue is not appropriately addressed, it will continue to result in unwanted fires and forest degradation, related smoke and gas emissions, and environmental and economic losses. A recent study in Sumatra revealed that, in many cases, (1) tenure conflicts between companies and communities, resulting from past government policies and practices, often trigger forest and land fires because of frustrations by the communities of being unable to have their claims heard in a fair and transparent judicial system; and (2) even with the use of military force, forest policy and management has largely failed to protect forest resources when local communities were not involved. The nature of the partnership between communities and companies in land use development is also an important factor in influencing the incidence and control of fire.

How Many People are Exposed to Sublethal Fire Smoke?

A good estimate of the magnitude of the population exposed to fire smoke would be a reality check on the suitability of predicting harm to people from fire through the use of conservatively low fire safety thresholds designed to assure no harm to even vulnerable subpopulations. If this total number of exposed people were far greater than the number of reported victims, then it would be fair to say that the implied safety factors in such a calculation are unreasonably large. Based on analyses of demographic and fire incidence data, it is estimated that between 310,000 and 670,000 people (excluding firefighters) in the U.S. are exposed to fire smoke each year in unwanted home fires alone. This compares to an average of 3,318 home civilian fire deaths and 11,505 civilian fire injuries per year involving smoke inhalation in part or in whole in reported home fires. There are thus 21 to 45 civilians exposed to toxic fire smoke per year for every one with a reported fire injury involving smoke inhalation. It is likely that most of these exposures are brief or are to the dilute smoke that is present outside the room of fire origin, where most survivors are located, and do not result in any noticeable consequences, let alone injury or death.

Runaway Fires, Smoke‐Haze Pollution, and Unnatural Disasters in Indonesia

Fires on Sumatra and Kalimantan have taken a heavy toll on Indonesia' remaining tropical forests. Drought exacerbates the fire hazard, but it does not cause the fires, most of which have been the result of inappropriate land‐use policies and practices. Peatland fires have emitted vast quantities of smoke that periodically blanket large parts of insular Southeast Asia, impairing visibility, disrupting travel, hampering economic activity, and posing serious health risks. The development agenda of Indonesia' New Order regime paid scant attention to forest management, including the need to detect, control, and suppress unwanted fires.

On The Thin Layer Boilover

The burning of a thin fuel-layer floating on water is a problem of interest in unwanted fires. Heat losses to the water below may cause its boiling and induce an eruptive vaporization of explosive and violent character referred to as thin-layer boilover. A few years ago the present authors began a systematic and comprehensive study of this complex phenomenon. The results emphasized the importance of heat transfer in the direction normal to the fuel and sublayer surfaces. They corroborated that boilover is due to the heterogeneous boiling nucleation at the fuellwater interface, in sublayer water that has been superheated. A wide range of boiling points fuels were tested including a crude-oil, a heating oil, and five single-component fuels. Some of the parameters of the process were varied to observe their effect on the boilover characteristics and, through them, some of the controlling mechanisms were inferred. The influence of the major parameters of the problem, specifically the initial fuel-layer thickness, the pool diameter, and fuel boiling point. on the temperature history of the fuel and water and time to the start of boilover, was studied. A simple, one dimensional, quasi-steady, heat conduction model helps to understand how these different problem parameters affect boilover. However due to its limitations, there was a need to develop a more elaborated model, unsteady and including in-depth radiation absorption. FIRE SAFETY SCIENCE-PROCEEDINGS OF THE SIXTH INTERNATIONAL SYMPOSIUM, pp 579-590 Copyright © International Association for Fire Safety Science

The Evolution of HAZARD, the Fire Hazard Assessment Methodology

The United States alone spends $700 billion a year on new and renovated construction. About 20% of this money assures safety from unwanted fires, and this portion includes the cost of insurance to families and businesses. This enormous cost could be reduced by introducing fire safe products to the building and transportation industries, both in the United States and abroad, and by introducing advanced detectors, suppression systems, and firefighting equipment to the fire protection industry. In order to show that these products and mechanisms are safe to use, industries need performance measures. Performance-based fire standards are currently being developed to augment prescriptive standards around the world.

Soot formation in hydrocarbon/air laminar jet diffusion flames

Soot processes within hydrocarbon/air diffusion flames are important because they affect the durability and performance of propulsion systems, the hazards of unwanted fires, the pollutant and particulate emissions from combustion processes, and the potential for developing computational combustion. Motivated by these observations, this investigation involved an experimental study of the structure and soot properties of round laminar jet diffusion flames, seeking an improved understanding of soot formation (growth and nucleation) within diffusion flames. The present study extends earlier work in this laboratory concerning laminar smoke points (l) and soot formation in acetylene/air laminar jet diffusion flames (2), emphasizing soot formation in hydrocarbon/air laminar jet diffusion flames for fuels other than acetylene. In the flame system, acetylene is the dominant gas species in the soot formation region and both nucleation and growth were successfully attributed to first-order reactions of acetylene, with nucleation exhibiting an activation energy of 32 kcal/gmol while growth involved negligible activation energy and a collision efficiency of O.53%. In addition, soot growth in the acetylene diffusion flames was comparable to new soot in premixed flame (which also has been attributed to first-order acetylene reactions). In view of this status, a major issue is the nature of soot formation processes in diffusion flame involving hydrocarbon fuels other than acetylene. In particular, information is needed about th dominant gas species in the soot formation region and the impact of gas species other than acetylene on soot nucleation and growth.

Quantifying the ignition propensity of cigarettes

AbstractResearch funded under the Fire Safe Cigarette Act of 1990 (United States Public Law 101–352) has led to the development of two test methods for measuring the ignition propensity of cigarettes. The Mock‐Up Ignition Test Method uses substrates physically similar to upholstered furniture and mattresses: a layer of fabric over padding. The measure of cigarette performance is ignition or non‐ignition of the substrate. The Cigarette Extinction Test Method replaces the fabric/padding assembly with multiple layers of common filter paper. The measure of perfomance is full‐length burning or self‐extinguishment of the cigarette. Routine measurement of the relative ignition propensity of cigarettes is feasible using either of the two methods. Improved cigarette performance under both methods has been linked with reduced real‐world ignition behavior; and it is reasonable to assume that this, in turn, implies a significant real‐would benefit. Both methods have been subjected to interlaboratory study. The resulting reproducibilities were comparable to each other and comparable to those in other fire test methods currently being used to regulate materials which may be involved in unwanted fires. Using the two methods, some current commercial cigarettes are shown to have reduced ignition propensities relative to the current best‐selling cigarettes.

Boilover burning of oil spilled on water

In-situ burning of fuels spilled on water is of interest as a means for cleaning up these spills. It also is a potential important hazard in unwanted fires. This paper reports the results of small-scale experiments that investigate the combustion of thin layers of heating oil on water, and the events that take place in this complex combustion process, which can lead to the occurrence of explosive burning, normally referred to as boilover. The work concerns primarily the influence of the initial oil-layer thickness and pool diameter on the burning rate, time to the start of boilover, burned mass ratio, boilover intensity, and temperature history of the oil and water. The temperature measurements show that the phenomenon may be due to boiling nucleation near the oil/water interface, in sublayer water that has been superheated. The violent eruptive vaporization of the water bubbles tends to atomize the oil layer above, with subsequent projection of burning droplets. The boilover intensity appears closely related to initial oil-layer thickness and pan diameter. This is discussed in terms of surface tension effects, and growth and expansion of the water bubbles at the nucleation sites.

Fire Physics - Promises, Problems, And Progress

The use of wanted fire leads necessarily to unwanted fires, which are fought by the fire services, designed against by the fire engineers, and observed and explained by the fire sciences. This paper explores the current position of one of those sciences fire physics, defined as the study of the physical mechanisms by which fire is initiated, grows throughout a system, and is extinguished. The motivations for pursuing given technical areas are examined (promises), the tasks to be performed are described (problems) and the accomplishments to date are summarized (progress). The field of Fire Physics is broken into four broad categories: I.) Fluid Dynamics, II.) Diffusion Flames, III.) Flame Spread and IV.) Compartment Modeling. An inclusive list of topics within each category is presented. Space constraints prohibit a more comprehensive review, however reference is made to many competent reviews already available. Due to the author's linguistic limitations, the English language literature is emphasized.

Legislation – Standards – Polymers

Many measures have to be adopted to ensure the safety of occupants from unwanted fires in buildings. This paper examines the work of fire prevention officers in local authority fire brigades to mitigate these problems by their use of the provisions of the Fire Precautions Act 1971. The implications of the proposals to amend the 1971 Act and the commitment of the Government to use appropriate standards for regulatory purposes are discussed

Student Recruiting: Linear Programming as Problem-Solver and Heuristic

6. Derry, Louis M, Fatal Fires in America, Journal, 73 (September 1979): 67-79. 7. Federal Emergency Management Agency, Fire in the United States: 1979, 2nd ed. (Washington, D.C.: U.S. Administration, 1982), p. 95. 8. Berl, Walter G, and Halpin, Byron M., Human Fatalities from Unwanted Fires, Journal, 73 (September 1979): 105-115. 9. Hemenway, David, United Problem (Harvard School of Public Health Working Paper, 1985). 10. Mierley, Marianne C., and Baker, Susan, P., Fatal House Fires in Urban Population, Journal of the American Medical Association, 249 (11) (March 18, 1983): 1466-68. 11. Gomberg, Alan and Clark, Louis P., Rural and Non-Rural Civilian Fatalities in Twelve States (Washington, D.C.: Federal Emergency Management Agency, 1982). 12. Hemenway, Fire Problem, op cit. 13. Hemenway, David, Monitoring and Compliance: The Political Economy of Inspection (Greenwich, CT: JAI Press, 1985), pp. 87-91. 14. Corman, Hope; Ignall, Edward J.; Rider, Kenneth L,; and Stevenson, Anne, Fire Casualties and their Relation to Company Response Distance and Demographic Factors (Santa Monica, CA: Rand Paper Series, 1975). 15. Federal Emergency Management Agency, Residential Smoke and Detector Coverage in the United States (Washington, D.C.: U.S. Administration, 1982).

Urban and wildland fire phenomenology

Mankind's concern with unwanted fires likely predates the first practical use of combustion in unrecorded history. Yet the science of fire protection has progressed more slowly than other aspects of combustion science. This state of affairs is due partially to the complexity of the problem and partially to the fact that relatively large technological payoffs generally are not anticipated to be obtained from scientific investigations of fires. Numerous promises and problems in the use of combustion in heat and power production, in locomotion and in industrial endeavors have generated intensive scientific efforts. By way of contrast, the ever-present fire problems have attracted fluctuating interest with a relatively low average level of concern. Although periodic disasters engender beliefs that more should be done in fire science, these beliefs often are short-lived and are replaced by more immediate concerns. Rarely has a disaster or a series of disasters provoked a program of scientific study of fire phenomena. The long-term efforts that have been mounted in the field instead have been motivated mainly by detailed comparative evaluations of the magnitude of the fire problem. There is reason to believe that today's rapid technological advances intensify problems of unwanted fires. Hosts of new processes and new combustible materials are emerging and finding their way into widespread use. Too often these innovations become commonplace before their fire hazards are properly understood. Therefore there seems to be justification for more extensive development and dissemination of knowledge in fire science. The present article has been prepared with the objective of bringing together many aspects of fire science for a nonspecialized audience. It is based on an undergraduate course by the same name, given only once, at the University of California, San Diego. It focuses on basic aspects of fire as a phenomenon, presented in an elementary but unified manner. It is more restricted than other treatments of the subject in that physiological, social, economic, organizational and operational aspects are not covered. However, it is broader in that both urban and wildland fires are considered equally; most presentations are slanted toward one or the other of these classes of fire problems. I hope that this article will help to introduce nonspecialists to the scientific phenomenology of fires.

Ignition of a Liquid Fuel Under High Intensity Radiation

Abstract The ignition of a liquid fuel under high intensity radiation was studied experimentally to obtain a fundamental understanding of the ignition mechanism and to aid in the selection of design improvements to minimize hazards of unwanted fires. The experiments were conducted using a CW CO2 laser with incident fluxes from 1000 to 5000 W/cm2and n-decane as the flammable liquid. The study of the effect of the container size showed 6 cm diameter by 5 cm depth sufficiently large to prevent container size effects on ignition. High speed photographs of ignition events showed the motion of decane prior to ignition and the onset of the ignition in the gas phase. The effect on ignition of the incident angle of the laser beam with respect to the decane surface was studied from 90° to 30°. On reducing the incident angle, the ignition delay time becomes longer and the minimum incident flux for ignition increases significantly. The proposed autoignition mechanism of decane by a CO2 laser is the absorption of the incident laser beam energy by the vapor plume.