ISO/TC 92/SC 3/WG 1 - Fire model

This document specifies requirements for the determination of methods and fire scenarios for fire threat assessment as a basis for designing and constructing large-scale fire tests. It covers different generic design requirements for large-scale fire test rigs to simulate the real fire scenarios of interest. This document addresses fire threats to people under acute exposure to fire effluents according to the evaluation of tenability conditions. It does not address any chronic effects of that exposure on susceptible populations and firefighters.

This document assesses the utility of physical fire models that have been standardized, are commonly used, and/or are cited in national or international standards, for generating fire effluent toxicity data of known accuracy. This is achieved by using the criteria established in ISO 16312-1 and the guidelines established in ISO 19706. The aspects of the models that are considered are: the intended application of the model, the combustion principles it manifests, the fire stage(s) that the model attempts to replicate, the types of data generated, the nature and appropriateness of the combustion conditions to which test specimens are exposed, and the degree of validity established for the model.

This document provides principles for characterizing the measured production of toxic gases from a laboratory fire test and provides bases for comparing the results between different types and scales of such tests. It also includes consideration of the uncertainties in the gas determinations. The combined uncertainty is a key factor in the ability to establish similarity or difference of test results. The sufficiency of the agreement between a bench-scale test and a real-scale test depends on the precision needed in the fire hazard or risk assessment, which is not covered by this document. This document defines the relevance and significance of toxic gas data from measurements in different fire tests. With such a definition it is possible to provide generic guidance on how such data can be compared between different sizes and types of fire tests. The combustion conditions represented by the fire test, other specific characteristics of the test and the test specimen, the sampling strategy of the fire effluents, and the analysis technique for the toxic gas species are the most important factors when defining the significance of the toxic gas data. This document is intended to serve as a tool for the a) definition of the relevance and significance of toxic gas data from fire tests, b) comparison of toxic gas data from fire tests of different scales and characteristics, and c) prediction of toxic gas data from a large-scale test based on small-scale data or vice versa. This document gives general guidance regarding comparison of toxic gas data between physical fire models of different scales, but is principally developed for the gases listed in ISO 13571, i.e. carbon dioxide (CO2), carbon monoxide (CO), hydrogen halides (HCl, HBr, HF), sulfur dioxide (SO2), hydrogen cyanide (HCN), nitrogen oxides (NO, NO2), formaldehyde (CH2O) and acrolein (C3H4O). This document is not applicable to characterization and comparisons of the toxicity of the effluents from fire tests.

ISO 16312-1:2016 provides technical criteria and guidance for evaluating physical fire models (i.e. laboratory combustion devices and operating protocols) used in effluent toxicity studies for obtaining data on the effluent from products and materials under fire conditions relevant to life safety.[9] Relevant analytical methods, calculation methods, bioassay procedures and prediction of the toxic effects of fire effluents can be referenced in ISO 19701, ISO 19702, ISO 19703, ISO 19706 and ISO 13344. Comparisons are detailed in ISO 29903. Prediction of the toxic effects of fire effluents can be referenced in ISO 13571 and ISO/TR 13571‑2.

ISO 29903:2012 provides principles for characterizing the measured production of toxic gases from a laboratory fire test and provides bases for comparing the results between different types and scales of such tests. It also includes consideration of the uncertainties in the gas determinations. The combined uncertainty is a key factor in the ability to establish similarity or difference of test results. The sufficiency of the agreement between a bench-scale test and a real-scale test depends on the precision needed in the fire hazard or risk assessment, which is not covered by ISO 29903:2012. ISO 29903:2012 defines the relevance and significance of toxic gas data from measurements in different fire tests. With such a definition it is possible to provide generic guidance on how such data can be compared between different sizes and types of fire tests. The combustion conditions represented by the fire test, other specific characteristics of the test and the test specimen, the sampling strategy of the fire effluents, and the analysis technique for the toxic gas species are the most important factors when defining the significance of the toxic gas data. ISO 29903:2012 is intended to serve as a tool for the definition of the relevance and significance of toxic gas data from fire tests, comparison of toxic gas data from fire tests of different scales and characteristics, and prediction of toxic gas data from a large-scale test based on small-scale data or vice versa. ISO 29903:2012 gives general guidance regarding comparison of toxic gas data between physical fire models of different scales, but is principally developed for the gases listed in ISO 13571, i.e., carbon dioxide (CO2), carbon monoxide (CO), hydrogen halides (HCl, HBr, HF), sulphur dioxide (SO2), hydrogen cyanide (HCN), nitrogen oxides (NO, NO2), formaldehyde (CH2O) and acrolein (C3H4O). It does not cover characterization and comparisons of the toxicity of the effluents from fire tests.

Defines the criteria for an acceptable fire model, reviews existing fire models ("box" furnace models, tube furnace models, radiant heat models) against these criteria, and proposes that fire models be selected for use through consideration of these criteria which includes a capacity to generate fire conditions characteristics of known stages of fire. Does not give a detailed analysis of the physics and chemistry of fire.