Fire Hazard Analysis Techniques

Available methods to estimate the potential impact of fire can be divided into two categories: risk-based and hazard-based. Both types of methods estimate the potential consequences of possible events. Risk-based methods also analyze the likelihood of scenarios occurring, whereas hazard-based methods do not. Fire risk analysis is described more fully in Section 3, Chapter 8, “Fire Risk Analysis. ” Section 3, Chapter 9, “Closed Form Enclosure Fire Calculations,” provides simple fire growth calculation methods. The goal of a fire hazards analysis (FHA) is to determine the expected outcome of a specific set of conditions called a fire scenario. The scenario includes details of the room dimensions, contents, and materials of construction; arrangement of rooms in the building; sources of combustion air; position of doors; numbers, locations, and characteristics of occupants; and any other details that have an effect on the outcome of interest. This outcome determination can be made by expert judgment, by probabilistic methods using data from past incidents, or by deterministic means such as fire models. “Fire models” include empirical correlations, computer programs, full-scale and reduced-scale models, and other physical models. The trend today is to use models whenever possible, supplemented if necessary by expert judgment. Although probabilistic methods are widely used in risk analysis, they find little direct application in modern hazard analyses. Probabilistic models are discussed in Section 3, Chapter 5, “Introduction to Fire Modeling. ” Typically, when the potential impact of fire is estimated, a hazard basis is used. When probabilities or frequencies are considered, it is usually in the context of determining whether or not a scenario is sufficiently likely to warrant further analysis. Hazard analysis can be used for one of two purposes. One is to determine the hazards that are present in an existing or planned facility. The other use is for design, where trial design strategies are evaluated to determine whether they achieve a set of fire safety goals. Hazard analysis can be thought of as a component of risk analysis. That is, a risk analysis is a set of hazard analyses that have been weighted by their likelihood of occurrence. The total risk is then the sum of all of the weighted hazard values. In the insurance and industrial sectors, risk assessments generally target monetary losses, since these dictate insurance rates or provide the incentive for expenditures on protection. In the nuclear power industry, probabilistic risk assessment has been the basis for safety regulation. Here the risk of a release of radioactive material to the environment is commonly examined, ranging from a leak of contaminated water to a core meltdown. Available fire hazard calculation methods range from relatively simple equations that can be performed with a hand calculator to complex methods that require powerful computers, and many methods that fall between. See also Section 2, Chapter 1, “Physics and Chemistry of Fire”; Section 3, Chapter 4, “Use of Fire Incident Data and Statistics”; Section 3, Chapter 5, “Introduction to Fire Modeling”; Section 3, Chapter 8, “Fire Risk Analysis”; Section 3, Chapter 9, “Closed Form Enclosure Fire Calculations”;