Richard W. Bukowski

Verification of a model of fire and smoke transport

Abstract A set of comparison between a comprehensive room fire model and a range of real-scale fire experiments is presented. For these comparisons, a zone-based model, CFAST (‘consolidated fire and smoke transport’ model) is used. The model predicts the evolution of a fire in a room and the subsequent transport of the smoke and toxic gases which result from this fire. These comparisons serve two purposes: to determine, within limits, the accuracy of the predictions for those quantities of interest to the users of the models (usually those extensive variables related to hazard), and to highlight the strengths and weaknesses of the underlying algorithms in the models to guide future improvements in this and other models. The predicted variables selected for comparison deal with both of these purposes. Although differences between the model and the experiments were clear, they can be explained by limitations of the model and of the experiments.

Defining flashover for fire hazard calculations

As the use of performance-based methods for evaluating the fire behavior of materials and systems becomes more widespread, objective criteria to judge fire behavior become more important. This paper reviews techniques for predicting the most common of these criteria, the onset of flashover. The experimental basis for working definitions of flashover is reviewed. Comparisons of available calculational procedures ranging from simple correlations to computer-based fire models that can be used to estimate flashover are presented. Although the techniques range in complexity and results, the various predictions give estimates commensurate with the precision of available experimental data.

FIRE SAFETY OF PASSENGER TRAINS: A REVIEW OF CURRENT APPROACHES AND OF NEW CONCEPTS

New alternative technologies have been developed which can be used to increase intercity passenger train operating speeds. These technologies include steel-wheel-on-rail and magnetic levitation (maglev) systems. Fire safety is an area of particular interest for these technologies, as well as for conventional intercity and commuter trains. While the historical fire record has been very good and few serious passenger train fires have occurred, minor incidents could develop into potential life-threatening events. The report presents a detailed comparison of the fire safety approaches used in the United States, France, and Germany. The strengths and weaknesses of current methods for measuring the fire performance of rail transportation systems are evaluated. An optimum systems approach to fire safety which addresses typical passenger train fire scenarios is analyzed and recommendations are presented to address the current state-of-the-art in materials testing.

Smoke measurements in large- and small-scale fire testing — Part I

A new extinction photometer design has been developed that will provide the stability and accuracy necessary for taking smoke measurements in fire testing.

Analysis of the Happyland Social Club Fire with Hazard I

The paper presents the reconstruction of the Happyland Social Club fire using the HAZARD I fire hazard assessment method along with an examination of four potential mitigation strategies: automatic sprinklers, a door at the base of the stairway to the second floor, a second means of egress from the second floor, or a noncombustible interior finish. The paper concludes that the traditional second means of egress might have not have eliminated the observed fatalities, and that the noncombustible interior finish or sprinkler options would, with the former being the more cost effective approach.

Evaluation of passenger train car materials in the cone calorimeter

Recent advances in fire test methods and hazard analysis techniques make it useful to re-examine passenger train fire safety requirements. The use of test methods based on heat release rate (HRR), incorporated with fire modelling and hazard analysis, could permit the assessment of potential hazards under realistic fire conditions. The results of research directed at the evaluation of passenger train car interior materials in the cone calorimeter are presented. These measurements provide data necessary for fire modelling as well as quantitative data that can be used to evaluate the performance of component materials and assemblies. The cone calorimeter test data were also compared with test data resulting from individual bench-test methods specified in the FRA fire safety guidelines, The majority of the tested materials which meet the current FRA guidelines show comparable performance in the cone calorimeter.

TOXIC HAZARD EVALUATION OF PLENUM CABLES .

Code provisions covering the installation of low voltage cables in plenum spaces above suspended ceilings used for environmental air are reviewed. A calculation procedure which could be used to estimate the potential toxicity of the decomposition products from these cables relative to the toxicity of the compartment fire necessary to decompose the cable insulation is presented. These estimates are used in a four-step procedure for estimating Smoke Toxicity Hazard proposed by the NFPA Toxicity Advisory Committee which is described. Example calculations for some typical cases and a discussion of their limitations are included.

Developing detector siting rules from computational experiments in spaces with complex geometries

Abstract The National Institute of Standards and Technology (NIST) is conducting a 4-year research project wherein a computational fluid dynamics (CFD) computer code is utilized to map temperature, flow velocities, and particle densities in spaces with complex ceiling geometries. Through parametric variation of independent variables for the fire and the space, the number and location of smoke or thermal sensors required to assure response prior to a critical fire size is determined. The first year addressed horizontal ceilings with open beams or joists, and the second year adds sloped ceilings. In addition to the geometric studies, several special studies have been conducted. These include detection of low energy fires (as low as 100 W), stratification of fire gases in spaces with a vertical thermocline which exceeds the plume temperature, and obstructions which do not come, completely to the ceiling. A unique method of relating the response of detectors to the predicted conditions has been developed which can be utilized with any CFD model or with experimental data. The data analysis is being used to produce siting rules for inclusion directly into existing codes. The paper will review the results of the first 2 years of the project and present some thoughts on the potential for these techniques to greatly improve the technical basis for the utilization of fire sensors in complex installations.

A prototype methodology for fire hazard analysis

The first version of a method for predicting the hazards to occupants involved in a building fire is described. The method and available computer software, called HAZARDI, can predict the time varying environment within a building resulting from a specified fire; the locations and actions of occupants; and the impact of the exposure of each of the occupants to the fire products in terms of whether the occupants successfully escape, are incapacitated, or are killed.

New Concepts for Fire Protection of Passenger Rail Transportation Vehicles

Recent advances in guided group transportation, fire test methods, and hazard analysis necessitate re-examination of requirements for fire safety. Several studies have indicated nearly random ability of current tests to predict actual fire behavior. A comparison of the approaches used in the United States, Germany, and France is presented. With the strengths and weaknesses of current methods for measuring the fire performance of materials used in rail transit systems reviewed, a direction is suggested in which most fire science-oriented organizations in the world are clearly headed - fire hazard and fire risk assessment methods supported by measurement methods based on heat release rate.