What is ISO/TR 9122-4 - Specification of a fire model about?
ISO/TR 9122 is a series on toxicity testing of fire effluents. One of the main causes of human losses in fires is exposure to fire effluent. ISO/TR 9122-4 is restricted to the consideration of fire models (i.e., laboratory combustion devices) used in fire effluent toxicity studies, together with suggestions for the appropriate use of the fire models in standard testing.
ISO/TR 9122-4 defines the criteria for an acceptable fire model, reviews existing fire 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 characteristic of known stages of fire.
Note: ISO/TR 9122-4 does not give a detailed analysis of the physics and chemistry of fire.
Who is ISO/TR 9122-4 - Specification of a fire model for?
ISO/TR 9122-4 on the specification of a fire model is useful for:
- Fire-fighting department
- Fire alarming manufacturers
- Quality control personnel
- Research and development facilities
Why should you use ISO/TR 9122-4 - Specification of a fire model?
Fire involves a complex and interrelated array of physical and chemical phenomena. As a result, it is essentially impossible to simulate all aspects of a real fire in laboratory-scale apparatus. This problem of fire model validity is perhaps the single most perplexing technical problem associated with all the fire testings. For fire models used in evaluating fire effluent toxicity, additional restrictions and criteria are necessarily imposed due to the need for the laboratory combustion to be compatible with bioassay procedures using live test animals. For example, reduced oxygen levels and heat must not, in themselves, be unduly compromising to exposed animals. At the same time, sufficiently high concentrations of fire effluents must be produced so as to obtain measurable toxicological effects. As a result of these restrictions, compromises must often be made which can further reduce the apparent validity of the fire model. Essentially two approaches are used to evaluate the toxicity of fire effluents i.e. those using full-scale fire models and those using small-scale fire models. In full-scale procedures, fire models consisting of a room, multiple rooms or a complete building are used which are intended to simulate as far as possible the full characteristics of fires including ignition, growth, and evolution of toxic fire effluents.
Full-scale methods are usually applied in tests of the toxic hazard presented by the fire, although some attempts have been made to model the main features of toxic hazards in small-scale tests. In small-scale fire models, it is considered possible to re-create the reactive chemical environments characteristic of various stages and types of fire conditions in terms of temperature, the presence or absence of flame and oxygen supply. Under these conditions, the relative yields of toxic products in the fire effluents from materials will be similar to those evolved at equivalent stages in full-scale fires. Thus, small-scale fire models are regarded as relevant to the testing of the toxic potencies of the chemical products evolved from materials under the defined decomposition conditions. These potency values may then be used as input data in toxic hazard assessments which take into consideration the dynamic characteristics of specific fire scenarios. Using ISO/TR 9122-4 you can specify fire models (i.e., laboratory combustion devices) used in fire effluent toxicity studies, together with suggestions for the appropriate use of the fire models in standard testing.