Fire Codes Research Articles

DEVELOPING PARTNERSHIPS WITH THE FIRE SERVICE TO ENHANCE FIRE PROTECTION ENGINEERING EDUCATION OPPORTUNITIES

Fire protection engineering is increasing in importance in Canada and other countries, especially with recent changes to building and fire codes. Fire protection engineering design is highly interdisciplinary, which can present challenges when developing courses in this area. At the University of Saskatchewan, this challenge has been partially addressed through partnerships with the fire service, and other universities and research organizations. This paper discusses the importance of considering the fire service in the design process, and provides examples of partnerships with the fire service in the Mechanical Engineering undergraduate program and in graduate research projects.

Numerically investigating fire suppression mechanisms for the water mist with various droplet sizes through FDS code

With rapid progress in computer capability recently, it becomes feasible to investigate the sophisticated phenomena related to the fire, especially for the interaction of fire and water spray, by way of the computational fluid dynamics (CFD). In this paper, a fire simulation CFD code_FDS is used to numerically investigate the different droplet sizes on the fire suppression/extinguishment mechanisms. The CFD models adopted in the FDS are first assessed against the previous experimental work of Kim and Ryou. The droplet size interested is varied from 100 μm to 1000 μm that is located within the droplet size range for a water mist. Based on the sensitivity simulations with different droplet sizes, the dependency of fire extinguishing time on the discharged droplet size can be obtained. The fire extinguishing time decreases with the decreasing droplet size for a mist with relatively fine droplet size since both the evaporation cooling and the oxygen displacement are the dominant mechanisms of fire suppression. However, this trend is reverse for a mist with larger-size droplets for the sake that the direct cooling of flame is the major suppression mechanism. These conclusions are also confirmed by comparing the simulation distributions of gas temperature, oxygen concentration, and steam concentration after the mist actuation and just before the fire extinguishment.

Local field potential phase and spike timing convey information about different visual features in primary visual cortex

The natural visual environment is characterized by both “what/where” aspects (image features such as contrast or orientation which are defined by the relationship between visual signals simultaneously presented at different points in space) and “when” aspects, describing the temporal variations of the image features. Both “when” and “what/where” information is necessary to describe and understand the natural visual environment, and to take appropriate behavioral decisions. While “where” can be considered embedded as retinotopy, it is likely that localized neural populations in the visual cortex keep a simultaneous representation of both “what” and “when” aspects of the visual stimuli. However, little is yet known about how the spike trains of neurons in primary visual cortex encode both sources of information. The traditional hypothesis in systems neuroscience is that sensory variables are represented by a rate code, i.e. all sensory information is encoded by the number of spikes emitted over relatively long time windows. Although the relevance of rate in encoding static features is well established, this code can be inherently ambiguous in changing environments [1] and it is unlikely that this code is rich enough to represent simultaneously different types of information. Therefore here we explore the hypothesis that the timing of spikes is a crucial variable in representing both “what” and “when” aspects of the natural visual environment. To address these issues, we recorded single unit activity and LFPs in primary visual cortex of opiate anaesthetized macaques during the binocular presentation of naturalistic color movies. By means of computational analysis, we extracted several image features (color, orientation, luminance, space and time contrast, motion) from the receptive fields of each single neuron. We then considered two different spike timing codes previously studied in both the auditory [2] and the visual cortex [3]. In the first code, which we call spike patterns code, sequences of spike times from single neurons are measured (with a resolution of the order of 10 ms) with respect to the time course of the external stimulus. In the second code, which we call phase of firing code, spikes are measured with respect to the phase of the concurrent low frequency LFPs recorded from the same electrode as the spikes. We then used these data to investigate systematically which types of neural codes carry information about the static features of the image and which neural codes carry information about the time course of these features. We found that both “when” and “what” aspects are encoded simultaneously by spike times of visual cortical neurons. However, “what” and “when” are encoded by two different neural information streams; “what” aspects are encoded (on a fine scale of few ms) by spike patterns, and “when” stimulus aspects are encoded by the phase of firing (on a coarse scale of hundreds of ms).

A Numerical Study on Operation Modes of Mechanical Ventilation in Underground Tunnels and Comparisons with Full-Scale Experiments and Existing Fire Codes in Taiwan

Due to land scarcity in greater Taipei area, continuously conversion from existing railroad to underground are performed to increase the land utility at different phases and span many years. In addition, integration issues between several transportation systems such as mass transit and high speed rail are also of great concerns. Fourth phase of Nangkang North Tunnel was completed and in full operation in September, 2008. During the construction period, fire codes in Taiwan for special constructions (e.g. ubnderground stations) are also going through various revisions while internationally, new regulations such as AS 4391 in Australia and NFPA130 in USA have been validated and updated. In order to verify the compliance of fire codes nationally and internationally, full scale experiments have been performed before opening to public service with emphasis on various operation modes of mechanical ventilation. This paper aims to numerically investigate and compare the effectiveness of CFD (Computational Fluid Dynamics) with experimental results. As a matter of fact, full scale experiments are implemented in fire codes in Taiwan for the structures which cannot fully comply with normal installation of fire equipments. While computational power and resources are improving tremendously in the past few years, we focus on the potentials to gain insightful information through numerical simulation and provide a repeatable reference for the engineers, designers and fire fighters as well as managerial levels in government before undertaking any full-scale experiment.

Hazards of combustion products: Toxicity, opacity, corrosivity, and heat release: The experts' views on capability and issues

AbstractThe science of understanding how fires burn and how heat smoke and gases are generated and affect people has progressed substantially in the last half century. The principles of facility design for life safety in fires have reached a degree of maturity. Standards and code provisions for fire detection, suppression and control have become the norm. Real‐scale (or nearly real‐scale) test methods for the flammability of furnishings and interior finish have been established. In addition, some tests have been developed that measure the results of the burning of a small sample from the finished product. Yet, while there have been numerous small‐scale apparatuses developed for assessing the generation of heat, toxic gases, and visible or corrosive smoke, these facets of life and property safety have not found widespread inclusion in building and fire codes. There has been an invigorated effort in ISO TC92 SC3, Fire Threat to People and the Environment, to develop a coherent and comprehensive set of fire safety standards and guidance documents for life safety. Smaller efforts are ongoing within some national and regional standards bodies. In November 2008, experts in this field gathered at The Royal Society in London to hear papers that captured the state of the art and to discuss where we might go from here. This paper summarizes the papers and the discussion from that meeting. Copyright © 2010 John Wiley & Sons, Ltd.

A mathematical model on adjacent smoke filling involved sprinkler cooling to a smoke layer

Conventional two-zone model determines the smoke filling time in buildings without considering the cooling effect of sprinkler spray on the smoke layer. However, many buildings have been required to install the sprinkler systems by fire codes. So, the conventional zone model was not able to accurately predict the development of smoke layer height in a sprinklers involved fire. In order to improve the prediction, the current zone model is revised with a new mathematical model developed by taking the sprinkler cooling effect into account. The heat transfer between smoke layer and sprinklers spray was mathematically calculated. By using the mathematical model, the smoke filling time in an adjacent space under the sprinkler cooling effect are calculated. A set of experiments were carried out to validate the model. The smoke layer height was experimentally measured. Results show that the model predictions agree well with the experimental results. The smoke filling becomes slower due to the reduced volumetric smoke flow under sprinkler cooling. The variation of sprinkler operating pressure has little influence on the smoke filling since the cooling gets less effective as the operating pressure increases.

Simulating Smoke Filling in Big Halls by Computational Fluid Dynamics

Many tall halls of big space volume were built and, to be built in many construction projects in the Far East, particularly Mainland China, Hong Kong, and Taiwan. Smoke is identified to be the key hazard to handle. Consequently, smoke exhaust systems are specified in the fire code in those areas. An update on applying Computational Fluid Dynamics (CFD) in smoke exhaust design will be presented in this paper. Key points to note in CFD simulations on smoke filling due to a fire in a big hall will be discussed. Mathematical aspects concerning of discretization of partial differential equations and algorithms for solving the velocity‐pressure linked equations are briefly outlined. Results predicted by CFD with different free boundary conditions are compared with those on room fire tests. Standards on grid size, relaxation factors, convergence criteria, and false diffusion should be set up for numerical experiments with CFD.

Analysis of and Study on the Difficulties in the Fire Protection Design of Large Commercial Complex

Fire properties of the large commercial complex has been summarized. Based on the fact that there are contradictions between what is required for the large commercial complex in the fire code and the real application in practice, difficulties in fire protection of designing large commercial complex have been analyzed.

Numerical investigation of sodium droplet ignition in the atmospheric air

The ignition behaviour of sodium droplets in the atmospheric air has been studied numerically with two available models of pre-ignition stage combustion. Surface reaction is very important in the pre-ignition stage, and the different reaction rate-controlling processes involved in this stage are explained using the shrinking core model. The droplet ignition behaviour is studied by considering the energy balance at the droplet surface in terms of rate of heat generation from the surface oxidation reaction and rate of heat loss to the ambient air. Ignition delay times are evaluated numerically using the two pre-ignition models with different ranges of values to the main parameters that can affect the ignition behaviour of the sodium droplets. Based on these results, the relative capability of the models has been brought out in predicting the droplet ignition behaviour, so that the better model could be chosen for the sodium spray fire analysis code being developed. Analysis results show that the reaction kinetics limited pre-ignition model predicts the limit of ignitability for sodium droplets under different initial and convective conditions, whereas the mass transfer limited pre-ignition model predicts this only under very low oxygen concentrations.

Case Studies of High-Rise Building Fires in Dhaka City with Reference to Building Fire Code of Japan

This article presents case studies of fire in high-rise buildings around Dhaka, the capital of Bangladesh, based on the findings of field surveys conducted by authors. Then it will sort out the problems in building fire prevention by examining actual fire cases and then suggest practical solutions, with reference to Building Fire Code in Japan.

Simulation of Emergency Evacuation in the Arrival Hall of a Crowded Airport

Evacuation in the arrival hall of a crowded airport terminal during emergency will be reported in this paper. Crowded movement under maximum allowed loading during emergency will give serious consequences. Safe evacuation is a concern to the Authority, especially for those terminals with difficulties in complying with the prescriptive fire codes. However, it is not feasible to carry out field tests to realize the evacuation time of the crowd during an emergency. Evacuation models were applied to study the evacuation pattern in the airport terminal. BuildingEXODUS and SIMULEX are two of the widely used evacuation models. Both models had been applied to study the evacuation in large and geometrically complex spaces with a high occupant level. These two models were applied to study the emergency evacuation in the arrival hall. Allowed figures on occupant loading in the local codes were used. Four sets of scenarios were assessed in the crowded areas to realize the evacuation time of occupants under fire and normal conditions. Results showed that jamming occurred around the staircases of the arrival hall. Occupants had to queue up with a long waiting time under crowded condition. Providing more direct exits of adequate width is an effective method to reduce the waiting time of occupants. Controlling the occupant loading with appropriate fire safety management would avoid having long queues formed at the exits and staircases of the airport terminal. Other means, such as clear exit signs, should be provided in the retail areas and arrival hall to ensure that the occupants can travel to the nearest exits with a shorter evacuation time.

Performance-Based Fire Safety Assessment of City Underwater Tunnel

Safe evacuation criterion was first analyzed for fire safety assessment of city underwater tunnel. Then a worst fire scenario of a real underwater tunnel was set up, and simulations on fire smoke spread and people evacuation were carried out based on this scenario. The available safe egress time (ASET) was derived from the fire simulation, while the required safe egress time (RSET) was derived from evacuation simulation. According to the performance-based fire code, fire safety assessment of the tunnel was carried out based on the comparison between ASET and RSET.

Simulation of Emergency Evacuation in the Arrival Hall of a Crowded Airport

Evacuation during emergency is a key issue to study. For the dense airport terminals, crowded movement under the maximum loading during emergency will give serious consequences. Safe evacuation is a concern to the Authority, especially for those terminals with difficulties in complying with the prescriptive fire codes. However, it is not feasible to carry out field tests to realize the evacuation time of the crowd during an emergency. Therefore, models simulating the evacuation of buildings are commonly used to study the evacuation pattern. BuildingEXODUS and SIMULEX are two of the widely used evacuation models, which were applied to study the evacuation in large and geometrically complex spaces with a high occupant level. Both models were applied to study the emergency evacuation in the arrival hall of the airport terminal in Hong Kong. Allowed figures on occupant loading in local codes were used. Four sets of scenarios were assessed in the crowded areas to realize the evacuation time of occupants under fire and normal conditions. From the simulated results on evacuation patterns, useful design parameters are derived. These are the maximum number of occupants leaving the zone, number of occupants leaving the hall within the target time, travel distances, waiting time and moving time of occupants in the airport terminal.

Investigating the burning characteristics of electric cables used in the nuclear power plant by way of 3-D transient FDS code

Burning characteristics of electrical cables are one of the key parameters for the fire hazard assessment of nuclear power plants (NPPs) since the cables are the essential sources of fire in the plants. A three-dimensional (3-D) transient computational fluid dynamics (CFD) code_FDS is adopted in this paper to simulate these characteristics related to the cable burning. Being one of the NRC licensing fire codes, the FDS includes the thermal-hydraulic equations, the turbulence model and the chemical combustion model, etc. In order to assess the CFD fire models used in this code, a burning test using the control cable with the outer jacket of polyvinylchloride (PVC) and the inner insulation of cross-linked polyethylene (XLPE) is conducted. The measured parameters associated with the burning characteristics include the heat release rate (HRR), O 2 depletion, and CO and CO 2 production, etc. Except the amount of O 2 consumption, the predicted transient behaviors of other parameters can reproduce the measured data. Based on the chemical combustion model in the FDS code, this discrepancy may be essentially resulted from the default value of hydrogen fraction ( H frac) contained in the soot since the soot yield for the burning of PVC material is high enough that the uncertainty in the H frac value has a prominent effect on the amount of O 2 consumption. This explanation can be confirmed by a benchmark calculation for simulating a burning test with the polymethylmethacrylate (PMMA) fuel of low-soot yield. The present simulation works can provide the useful information for the plant staff or the researcher as they would perform the fire hazard analysis in the NPPs using the FDS code.

Examination of Initialization and Geometric Details on the Results of CFD Simulations of Diesel Engines

Computational fluid dynamic simulations using the AVL FIRE and KIVA 3V codes were performed to examine commonly accepted techniques and assumptions used when simulating direct injection diesel engines. Simulations of a steady-state impulse swirl meter validated the commonly used practice of evaluating the swirl ratio of diesel engines by integrating the valve flow and torque history over discrete valve lift values. The results indicate the simulations capture the complex interactions occurring in the ports, cylinder, and honeycomb cell impulse swirl meter. Geometric details of engines due to valve recesses in the cylinder head and piston cannot be reproduced axisymmetrically. The commonly adopted axisymmetric assumption for an engine with a centrally located injector was tested by comparing the swirl and emissions history for a noncombusting and a double injection low temperature combustion case with varying geometric fidelity. Consideration of the detailed engine geometry including valve recesses in the piston altered the swirl history such that the peak swirl ratio at TDC decreased by approximately 10% compared with the simplified no-recess geometry. An analog to the detailed geometry of the full 3D geometry was included in the axisymmetric geometry by including a groove in the cylinder head of the mesh. The corresponding emissions predictions of the combusting cases showed greater sensitivity to the altered swirl history as the air-fuel ratio was decreased.

Thermocouple Response in Fires, Part 2: Validation of Virtual Thermocouple Model for Fire Codes

A virtual thermocouple model for high fidelity multiphysics computer simulation is introduced in this article. Detailed thermocouple and gas temperature (Coherent Anti-Stokes Raman Scattering) measurements were performed using a well-controlled, adiabatic, flat-flame Hencken burner, which provided data for validating the thermocouple model in a Sandia National Laboratories fire code. Comparison of simulation results to test data indicated a mean error of 6% between the thermocouple reading and predicted temperature.

Large eddy simulation of fire plumes

FireFOAM, a new fire modeling code based on the OpenFOAM platform ( www.openfoam.org), is developed and applied to model a series of purely buoyant fire plumes with heat release rates from 14 to 58 kW. The calculations are compared with McCaffrey’s (1979) experiments. The simulation results demonstrate good quantitative agreement with experimental measurements, and show the scaling relations of mean temperature and velocity in the continuous flame, intermittent and plume regions. The numerical simulations are shown to be strictly conservative in energy. Predicted flame heights and entrainment rates also compare well with experimental correlations. The good agreements in all aspects examined show that the current CFD model performs well for small-scale fire plumes. Turbulent fluctuation intensities and PDF of mixture fraction are presented to gain more insights into the structure of fire plumes.

Metaphorical Invention in Early Photojournalism: New York Times Coverage of the 1876 Brooklyn Theater Fire and the 1911 Shirtwaist Factory Fire

Rorty (1989) argued that integrating unique metaphors into public discourse during moments of social instability functions to catalyze new moral norms and community identities. By analyzing New York Times coverage of two historical incidents of tragedy (i.e., the 1876 Brooklyn Theater fire and the 1911 Triangle Shirtwaist Factory fire), we assess Rorty's position in light of this coverage and the legal aftermath of each tragedy (e.g., the Brooklyn fire was associated with few changes in policy while the Shirtwaist Factory fire has been celebrated for catalyzing important changes in fire safety code and state labor laws). That these two events transpired before and after the emergence of photojournalism in daily newspapers also allows us to consider the role that “phototexts” may play in creating opportunities for metaphorical invention. Overall, we argue that two phototext-driven metaphors—equating factory workers with products and industry with a deathtrap—illuminated a powerful vocabulary of justice in the coverage of the Shirtwaist Factory fire that was not evident in the Brooklyn fire. We conclude the essay by laying out broader methodological implications for scholars of rhetorical and metaphorical criticism and considering the power of the phototext to further reform discourse.

A national set of hydrogen codes and standards for the United States

In 2003, the U.S. Department of Energy (DOE) initiated a project to coordinate the development of a national template of hydrogen codes and standards for both vehicular and stationary applications. The process consisted of an initial evaluation to find any gaps in the existing hydrogen codes and standards, and to define the codes and standards required to fill these gaps. These codes and standards were to be developed by several standards development organizations (SDOs). This article describes the three levels of codes and standards that address hydrogen technologies for the built environment.•Level 1—Primary adopted building and fire codes.•Level 2—Hydrogen-specific codes and standards references in primary adopted code.•Level 3—Hydrogen-specific component standards referenced in hydrogen-specific codes.Also described is the progress to date in populating these three levels with the required hydrogen codes and standards.

Body burdens of brominated flame retardants and other persistent organo-halogenated compounds and their descriptors in US girls.

Levels of brominated flame retardants are increasing in US populations, yet little data are available on body burdens of these and other persistent hormonally active agents (HAAs) in school-aged children. Exposures to such chemicals may affect a number of health outcomes related to development and reproductive function. Determine the distribution of biomarkers of polybrominated diphenyl ethers (PBDEs), polychlorinated biphenyls (PCBs), and organo-chlorinated pesticides (OCPs), such as DDT/DDE, in children, and their variation by key descriptor variables. Ethnically diverse cohorts of girls 6-8 y old at baseline are being followed for growth and pubertal development in a multi-site, longitudinal study. Nearly 600 serum samples from the California and Ohio sites were analyzed for lipids, 35 PCB congeners, 11 PBDE congeners, and 9 OCPs. The biomarker distributions were examined and geometric means compared for selected analytes across categories of age, race, site, body mass index (BMI), parental education, maternal age at delivery, and breast feeding in adjusted models. Six PBDE congeners were detected among greater than 70% of samples, with BDE-47 having the highest concentration (median 42.2, range 4.9-855 ng/g lipid). Girls in California had adjusted geometric mean (GM) PBDE levels significantly higher than girls in Ohio. Furthermore, Blacks had significantly higher adjusted GMs of all six PBDE congeners than Whites, and Hispanics had intermediate values. GMs tended to be lower among more obese girls, while other variables were not strongly associated. In contrast, GMs of the six PCB congeners most frequently detected were significantly lower among Blacks and Hispanics than Whites. PCBs and the three pesticides most frequently detected were also consistently lower among girls with high BMI, who were not breast-fed, whose mothers were younger, or whose care-givers (usually parents) were less educated. Girls in California had higher GMs than in Ohio for the pesticides and most PCB congeners, but the opposite for CB-99 and -118. Several of these potential HAAs were detected in nearly all of these young girls, some at relatively high levels, with variation by geographic location and other demographic factors that may reflect exposure pathways. The higher PBDE levels in California likely reflect differences in fire regulation and safety codes, with potential policy implications.