Dow fire and explosion index

The hazard classification guide developed by the Dow Chemical Company and published by the American Institute of Chemical Engineering, Dow (1994) (www.aiche.org), gives a method of evaluating the potential risk from a process, and assessing the potential loss. 

A numerical Fire and explosion index (F El) is calculated, based on the nature of the process and the properties of the process materials. The larger the value of the F El, the more hazardous the process, see Table 9.3. 

Fire and explosion index range Degree of hazard 

To assess the potential hazard of a new plant, the index can be calculated after the Piping and Instrumentation and equipment layout diagrams have been prepared. In earlier versions of the guide the index was then used to determine what preventative and protection measures were needed, see Dow (1973). In the current version the preventative and protection measures, that have been incorporated in the plant design to reduce the hazard-are taken into account when assessing the potential loss in the form of loss control credit factors. 

It is worthwhile estimating the F El index at an early stage in the process design, as it will indicate whether alternative, less hazardous, process routes should be considered. 

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Methods for performing hazard analysis and risk assessment include safety review, checkhsts, Dow Fire and Explosion Index, what-if analysis, hazard and operabihty analysis (HAZOP), failure modes and effects analysis (FMEA), fault tree analysis, and event tree analysis. Other methods are also available, but those given are used most often. 

Dow Fire and Explosion Index. The Dow Eire and Explosion Index (3) is a procedure usehil for determining the relative degree of hazard related to flammable and explosive materials. This Index form works essentially the same way as an income tax form. Penalties are provided for inventory, extended temperatures and pressures, reactivity, etc, and credits are appHed for fire protection systems, process control (qv), and material isolation. The complete procedure is capable of estimating a doUar amount for the maximum probable property damage and the business intermptionloss based on an empirical correlation provided with the Index. 

Quantitative Fire and Explosion Index (FExplosion Index Hazard Classification Guide, 1994 Lees, 1980, pp. 149-160). The F EI is used to rate the potential of hazard from fires and explosions. Its purpose is to quantify damage from an incident. It identifies equipment that could contribute to an incident and ways to mitigate possible incidents. It is a way to communicate to management the quantitative hazard potential. 

Dow Fire and Explosion Index (F EI) A method (developed by Dow Chemieal Company) for ranking the relative fire and explosion risk assoeiated with a proeess. Analysts ealeulate various hazard and explosion indexes using material eharaeteristies and proeess data. 

Tools are available to assist in comparing the risk associated with two or more different processes. For example, the first sheet of the Dow Fire and Explosion Index (FEI) (Dow, 1994b) ranks the safety characteristics of the process from a fire/explosion standpoint, without taking credit for protective and mitigation features. The Dow Chemical Exposure Index (CEI) (Dow, 1994a) and Id s Mond Index (ICI, 1985 Tyler, 1985) are other ranking tools. 

The approach to developing metrics for process safety is analogous to those that might be used to assess Occupational Exposure risk. One can cite as well several indices that have been developed as metrics for estimating and ranking the safety of a given process or chemical reaction, such as the DOW fire and explosion index,the Stoessel index ° for hazard assessment and classification of chemical reactions, the Inherent Safety Index, the Prototype Index for Inherent Safety, amongst others. ... 

Other techniques that take into account some site-specific conditions, such as the Dow Fire and Explosion Index (Ref. 34) and the Mond Index (Ref. 39), have been used to prioritize buildings for evaluation. The results of these indices should be used in conjunction with consideration of other factors, rather than as stand-alone criteria. These other factors might include an evaluation of the effects of confinement and/or congestion-induced turbulence on the potential for blast. 

Figure 9.2. Dow Fire and Explosion Index calculation form.

More detailed check lists are given by Carson and Mumford (1988) and Wells (1980). Balemans (1974) gives a comprehensive list of guidelines for the safe design of chemical plant, drawn up in the form of a check list. A loss prevention check list is included in the Dow Fire and Explosion Index Hazard Classification Guide, Dow (1987). 

A hazards survey can be as simple as an inventory of hazardous materials in a facility or as complicated as a rigorous procedure such as the Dow Fire and Explosion Index (F EI)2 and the... 

Figure 10-3 Form used in the Dow Fire and Explosion Index. The figures and tables referenced in the form are provided in the index booklet. Source Dow s Fire and Explosion Index Hazard Classification Guide, 7th ed., (1994). Reproduced by permission of the American Institute of Chemical Engineers.

This problem requires student access to the Dow Fire and Explosion Index manual.) In a devolatilizer, a solvent (60% cyclohexane and 40% pentane) is removed from a... 

The Finnish legislation (Pyotsia, 1994) classifies the flammability of chemical substances on the basis of their flash and boiling points. This is similar to the European Union Directives concerning hazardous substances. Also the Dow Fire and Explosion Index (1987) and Edwards Lawrence (1993) have been used similar approaches. 

Also Dow Fire and Explosion Index (1987) considers corrosion risks, but the penalties are given through unacceptable corrosion rates. Design standards also include advice of acceptable corrosion rates (Uhlig and Reviev, 1985). 

Various standard-setting groups, including NFPA and Factory Mutual, provide guidance for separation of potentially hazardous equipment and processes. Dow achieves adequate spacing between critical process units, and between Dow installations and neighboring properties, by applying the Dow Fire and Explosion Index and a Chemical Exposure Index. 

One measure of the inherent safety of a process with respect to fire and explosion risk is the Dow Fire and Explosion Index (12). Table 1 shows examples of the impact of inventory reduction on the Fire and Explosion Index. 

The Dow Fire and Explosion Index (FEI) (12) and the Dow Chemical Exposure Index (CEI) (14) are two commonly used tools that measure inherent safety characteristics. Gowland (25) reports on the use of the FEI and CEI in the development of safety improvements for a urethane plant. Tables 1 and 2 illustrate the application of the FEI and CEI in measuring inherent safety characteristics of process design options. These indices measure the inherent safety characteristics of processes in only two specific areas—fire and explosion hazards and acute chemical inhalation toxicity hazards. Other indices would be required to evaluate other types of hazards. 

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