NFPA 556 Guide on Methods for Evaluating Fire Hazard to Occupants of Passenger Road Vehicles

1.1 Scope.
1.1.1 This guide addresses issues associated with the development of hazardous conditions from fire involving passenger road vehicles and the time available for safe egress or rescue.

1.1.2 This document provides guidance toward a systematic approach of the determination of the relationship between the properties of passenger road vehicles, including the materials, components and systems, and the development of hazardous conditions in the vehicle. This approach can include small-scale testing, full-scale testing of systems or entire vehicles, and computer modeling techniques in specified, well-defined scenarios.

1.1.3 The principles and concepts presented in this guide provide a methodology that can be used to determine the effects of changes in design or in the properties of materials, components, and assemblies in passenger road vehicles on the development of hazardous fire conditions in passenger road vehicles in response to specified well-defined scenarios.

1.1.4 This guide provides a methodology that can be used in the selection of materials and design of components and systems,with the intent of providing a desired level of fire safety to occupants in passenger road vehicles in response to specific fire scenarios.

1.1.5 The use of this guide cannot eliminate all fire risk in passenger road vehicles.

1.1.6 The uncertainty of the fire hazard analysis resulting from the application of this guide is a function of the accuracy,
precision, and relevance of the data, correlations, test methods, calculations, and simulations used.

1.2 Purpose.

1.2.1 The purpose of this document is to provide guidance and tools for persons investigating methods to decrease the
fire hazard or fire risk in passenger road vehicles by providing additional time for occupants of the passenger road vehicle to be able to exit or be rescued in case of the occurrence of a fire involving the passenger road vehicle.

1.2.2 This document is intended to provide guidance for a hazard-based assessment for the development of hazardous
conditions from fire involving passenger road vehicles. This document does not provide guidance for a complete riskbased assessment.Arisk analysis, taking into account the probability and consequences of an event or events, can help focus passenger road vehicle safety efforts on solutions with the greatest impact on passenger road vehicle–related deaths.Strategies for reducing fire deaths in passenger road vehicles should not adversely affect efforts to reduce the overall number of deaths in passenger road vehicles. This statistic can be gauged by comparing the estimated lives saved per year by various strategies.

1.2.3 Flammability is one of a number of material properties to be considered in the design of components for passenger
road vehicles. The physical properties of materials used in passenger road vehicles affect the vehicles’ overall safety (including crashworthiness and fire safety), fuel economy, emissions (both tailpipe and evaporative emissions), manufacturability, utility, and durability. Optimizing a material for flammability could result in substantial degradation of other properties of that material, which could, in turn, render that material unsuitable for use in its intended application in a passenger road vehicle. Material properties that have been found to affect the overall safety, fuel economy, emissions, manufacturability, utility, and durability of passenger road vehicles and are currently considered when selecting a material for use in a passenger road vehicle are discussed in this guide. Therefore, proposed changes to flammability properties of a material or component should also consider how those changes could affect the properties discussed in this guide.