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Fire Loss Reduction |
The ability to make quantitative predictions of the hazards associated with fires in and around structures rests on an understanding of fire dynamics and the underlying physical principles that control these phenomena. We gain understanding of fire dynamics from computer simulations based on advanced large eddy simulation techniques in computational fluid dynamics as well as laboratory experiments. The result is a sophisticated computational tool that predicts the spread, growth, suppression, and impact of fires. Large eddy simulation techniques have been applied at NIST to study a variety of diverse fire response issues such as the dispersion of smoke plumes from oil-spill fires and the control of warehouse rack storage fires. The unique NIST contribution has been quantitative prediction of critical parameters such as the ground-level deposition of smoke particulate from oil fires and the time sequence of sprinkler activation in warehouse rack storage fires. We are developing a method to predict and visually display the spread of fires in wildland and urban areas on a site-specific basis. This method involves both the applications of computational wind engineering and enhanced high-resolution fire modeling. Our goal is to resolve the influence of individual trees and structural design elements in the analysis of resistance to fire spread. We are also working to create computationally efficient models for radiative and convective heat transfer in large fires. Results of this work will improve the prediction of ignition, fire spread, and exposure environments for firefighters. Contact: Anthony
Hamins Every year approximately 100 firefighters are killed in the line of duty. Many of these fatalities and numerous injuries could be reduced by applying new and existing technology developed from ongoing fire research. We have developed a number of computer-based models for predicting the impact of fire on buildings, occupants, and firefighters. Typically, the models predict the spread of the fire and its combustion products. We have developed a model, FDS/Smokeview, that provides a three-dimensional visualization of fire development in a building. This model has been used to assist with investigations of firefighter fatalities with the aim of preventing similar incidents in the future. This model also is being used for fire investigation research. Also, we have been conducting full-scale fire experiments to investigate the use of new measurement technologies in the fire environment. These studies have included the use of infrared cameras to measure temperature, lasers and sonar to measure displacement, and sound to predict the onset of combustion. Some of these technologies, such as infrared, are beginning to be used in actual fires. Currently, we are
developing a model to predict heat transfer through firefighter protective
clothing. The protective clothing industry, researchers, and firefighting
training officers have expressed interest in the results of this effort.
This model could be used by manufacturers in the design and development
of protective clothing with enhanced levels of safety. This model also
could be used as a training tool for firefighters to help them understand
the capabilities and limitations of their protective garments under a
variety of thermal conditions. This knowledge should assist in the development
of computer-based firefighter training programs that link protective clothing
performance to firefighting tactics. Contact: Nelson Bryner Annual fire deaths in the United States are now only half of what they were in 1975. This improvement can be attributed to a better understanding of the fire performance of materials and products and to the application of technology such as the smoke alarms found in nearly 95 percent of homes. Stringent controls on material flammability and the use of fire alarm and sprinklers has driven fire deaths in non-residential structures to below 120 per year for the entire country. Key to these advances has been the development of engineering analysis methods that allow the understanding of the highly complex interactions among materials and building designs and protection systems that can mitigate fire losses. NIST has been at the forefront of most of these advances. The product performance and installation rules for home smoke alarms came from NIST research and this work is credited by most as the primary reason for halving the fire death rate. NIST is now engaged in a re-examination of the performance and effectiveness of modern smoke alarms in current homes with furniture and other contents that differ significantly from 1970s households. In non-residential buildings, we are developing ways to use the data contained in a building's fire detection and alarm system to provide valuable, incident management information to the fire service to improve safety and efficiency. This information would be presented through a standard fire service interface that would be used by every manufacturer. Fire models and engineering analysis methods are now accepted in many countries as alternative ways of demonstrating compliance with the fire safety objectives for buildings. The methods in most widespread use globally were developed by NIST. Further, NIST has provided leadership in demonstrating the proper use and validity of these methods. Based on this NIST work there is now a general, worldwide consensus on the conduct of quantitative fire hazard and fire risk analysis. Contact: William
Davis Large fires can result from industrial or transportation accidents, natural disasters, arson, or when fire protection systems in constructed facilities fail to perform adequately. While these fires present a hazard to building occupants, firefighters, and the surrounding area, little is known about their characteristics, their growth and control, and methods of mitigating their impact. We are performing research and developing techniques to measure and predict the behavior of large fires and the action of building fire protection systems. Large building fires involve the interaction of strongly buoyant gas flows and thermal radiation with complex structures and, in some cases, automatic fire suppression systems. Experiments to evaluate industrial fire behavior and the performance of fire suppression systems are being conducted to provide information that can be used to reduce vulnerability to large fires. NIST is a leader in field fire measurement. Information from these studies, performed at sites of opportunity in cooperation with industry and fire service organizations, provides valuable data not obtainable in laboratory experiments. The development of robust field measurement techniques and equipment is a continuing activity. Data are used to develop and evaluate predictive models and standard test methods. As an example, we measure smoke plumes from large, open-air oil-spill fires to help develop and evaluate computer models for smoke movement. Contact: Nelson Bryner Fire research literature and data have been fragmented and are not easily identifiable. This barrier may force researchers to repeat their searches. It may also be an impediment in the development of a better product. To address the situation, the Fire Research Information Services (FRIS) was established as a resource both to the NIST staff and to fire protection engineers, scientists, and fire service personnel around the world. The FRIS 60,000-item document collection is freely available through FIREDOC; via the World Wide Web. The collection and exchange of data will continue to be critical to the needs of the fire community at large, as well as product developers. Contact: William Davis The damage from fires that are detected quickly can be kept small. NIST researchers are studying "fire signatures" to enable the development of a new generation of detectors. The signals from these detectors would be analyzed electronically to alert occupants or suppression devices, perhaps even before flames exist. The research also is intended to provide an understanding of technology for avoiding the high false-alarm rate of current detectors. NIST has devised a fire-emulator/detector-evaluator that has been identified by industry as a principal stimulant to the development and commercialization of new fire alert devices. The emulator provides a well-controlled environment in which fire sensors can be exposed to highly reproducible, time-varying concentrations of combustion products at predetermined temperatures and flow velocities to accurately determine the sensitivity and utility of new detector designs. Using this device, industrial designers can demonstrate how discriminating detector systems respond at the start of a fire. Contact: George Mulholland Rapid, effective response to a fire is essential to improve life safety and avert major property loss. Halon fire suppressants have long been used to protect the most important, sensitive, and irreplaceable facilities. Production of these chemicals now has been halted due to their deleterious effect on stratospheric ozone. We are leading research into replacements for the halons, and are working closely with the industries and federal agencies that need alternative suppression capability, the potential manufacturers of advanced fire suppression technologies, and other researchers in the field. We are studying the mechanisms of highly efficient flame extinguishants to help identify new chemicals for practical use, investigating the transport properties of gaseous and liquid suppressants to optimize their effectiveness, and developing performance measures for new fire suppression technologies. Contact: George Mulholland The modern fire-safety professional has become dependent on quantitative measures of fire performance, whether in terms of specifying commercial products or in presuming the validity of the ever more pervasive fire models. This requires that the measurement methods themselves be of reliable accuracy and known precision. However, nearly all the current fire characterization techniques have been in use for decades and have not incorporated the great strides made in instrumentation and data acquisition abilities. In addition, these techniques carry systematic and random errors that have not been adequately characterized, making questionable their reliability in safety assessments. NIST research is directed at modernizing fire measurements. The focus is on several areas: determining the needs of the fire community and analyzing the capability of current measurement approaches to meeting those needs; improving standard procedures for measuring temperatures and flow in fire environments; developing a new and universal method for measuring smoke production in full-scale fire tests; and assessing the potential for new laser optical techniques for in situ measurements in harsh fire environments. The results will enable the development of more accurate fire models and will enhance confidence in fire-model-dependent, performance-based fire codes. Contact: George Mulholland The materials industry is seeking products with low flammability that will not pose environmental hazards over their life cycles. NIST is working on several key research areas needed to produce natural and synthetic polymer and composite materials that can meet these goals. One area is the measurement of flammability properties by bench-scale methods directly relevant to real fires. Also important is the development of mathematical models that use the measured flammability properties as inputs to predict fire performance of materials in the conditions of actual use. Another research area concerns approaches to environmentally acceptable, char-forming flame retardant treatments for flaming and smoldering combustion. This effort includes studying the physical and chemical nature of char and how its properties can be enhanced. Low flammability nanocomposites are an area intense interest currently. The group is also developing high throughput methods for the study of polymer combustion. Theoretical modeling using molecular dynamics and quantum mechanics complement the experimental work to develop a technical basis for the design of a new generation of fire-resistant materials which, while retaining their intended-use properties, will be low in combustion toxicity and safe for the environment. Contact: Jeffrey Gilman
Date
created:
April 24, 2002 |