Explosion method INDEX

Process industry has used the Dow Fire and Explosion Hazard Index (DOW, 1987) and the Mond Index (ICI, 1985) for many years. These indices deal with fire and explosion hazard rating of process plants. Dow and Mond Indices are rapid hazard-assessment methods for use on chemical plant, during process and plant development, and in the design of plant layout. They are best suited to later design stages when process equipment, chemical substances and process conditions are known. 

The Dow Fire and Explosion Hazard Index, the Mond Index, Hazop and PIIS are discussed here in more detail. The methods and their elements are also presented in Table 1. 

Femtosecond pulsed lasers have been used to manufacture photonic devices (splitters, interferometers, etc.) and gratings. An ultrafast-laser driven micro-explosion method using a tightly focused femtosecond laser was exploited to fabricate three-dimensional (3D) void-based diamond lattice photonic crystals in a low refractive index polymer material (solid resin) [62]. 

Microscopy (qv) plays a key role in examining trace evidence owing to the small size of the evidence and a desire to use nondestmctive testing (qv) techniques whenever possible. Polarizing light microscopy (43,44) is a method of choice for crystalline materials. Microscopy and microchemical analysis techniques (45,46) work well on small samples, are relatively nondestmctive, and are fast. Evidence such as sod, minerals, synthetic fibers, explosive debris, foodstuff, cosmetics (qv), and the like, lend themselves to this technique as do comparison microscopy, refractive index, and density comparisons with known specimens. Other microscopic procedures involving infrared, visible, and ultraviolet spectroscopy (qv) also are used to examine many types of trace evidence. 

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. 

The Dow Fine and Explosion Index is a useful method for obtaining an estimate of the relative fine and explosion hazards associated with flammable and combustible chemicals. However, the technique is very procedure oriented, and there is the danger of the user becoming more involved with the procedure than the intent. 

Dow Eire and Explosion Index (E El) A method (developed by Dow Chemical Company) for ranking the relative fire and explosion risk associated with a... 

The Mond Index (ICI, 1985) has been developed from the 1973 version of the Dow F E Index. The principal modifications to the Dow method include (Lees, 1996) 1) wider range of processes and storage installations can be studied, 2) covers processing of chemicals having explosive properties, 3) improved hazard consideration for hydrogen, 4) additional special process hazards, 5) toxicity included into the assesment. 

In the Mond Index the plant is divided into individual units on the basis of the feasibility of creating separating barriers. One of the factors taken into account in the index is therefore plant layout. The potential hazard is expressed in terms of the initial value of a set of indices for fire, explosion and toxicity. A hazard factor review is then carried out to see if design changes reduce the hazard, and intermediate values of the indices are determined. Offsetting factors for preventative and protective features are applied and the final values of the indices, or offset indices, are calculated. The elements of the Mond method are listed in Table 1. 

Chemical Exposure Index (CEI) (Chemical Exposure Index, 1994 Mannan, 2005, pp. 8/22-8/26.) The CEI provides a method of rating the relative potential of acute health hazard to people from possible chemical release incidents. It may be used for prioritizing initial process hazard analysis and establishing the degree of further analysis needed. The CEI also may be used as part of the site review process. The system provides a method of ranking one risk relative to another. It is not intended to define a particular containment system as safe or unsafe, but provides a way of comparing toxic hazards. It deals with acute, not chronic, releases. Flammability and explosion hazards are not included in this index. To develop a CEI, information needs include... 

It is common to compare the output of different explosives as their TNT equivalent , this being the weight of TNT that would produce the same explosive effect in similar circumstances. In the Berthelot method, the TNT equivalent is taken as the ratio of the power index of the explosive divided by the power index of TNT. The result is usually expressed as a percentage. 

Explosive Power vs Oxygen Balance, Correlation of. The relationship of oxygen balance to expl power as measured by ballistic mottathas been studied empirically. Starting from modified oxygen, balance developed for detonation velocity calculations, a numerical measure called the power index is derived which correlates closely the features of molecular structure with.the power values. Expl power has also been expressed as an additive function of details of molecular structure. This is the basis for a method whereby power values may be derived which agree with experimental results to about... 

Predictive hazard evaluation procedures may be required when new and different processes, designs, equipment, or procedures are being contemplated. The Dow Fire and Explosion Index provides a direct method to estimate the risks in a chemical process based upon flammability and reactivity characteristics of the chemicals, general process hazards (as exothermic reactions, indoor storage of flammable liquids, etc.) and special hazards (as operation above the flash point, operation above the auto-ignition point, quantity of flammable liquid, etc.). Proper description of this index is best found in the 57-page Dows Fire and Explosion Index, Hazard Classification Guide, 5 th ed., AIChE, New York, 1981. 

Wheeler (1936) uses a different method of determining inflammability. Having determined whether a given dust is explosive, he next proceeds to add known percentages of inert dust such as fuller s earth (200 I.M.M.-mesh) until the dust is no longer explosive. This critical point is called the index of inflammability." If the amount of fuller s earth used is denoted by / (in percent), the index of inflammability I may be written... 

The safety and loss prevention guide developed by the Dow Chemical Company provides a method for evaluating the potential hazards of a process and assessing the safety and loss-prevention measures needed. In this procedure, a numerical Fire and Explosion Index is calculated, based on the nature of the process and the properties of the materials. The index can be used two different ways. In the preliminary design, the Dow index will indicate whether alternative,... 

The Dow index applies only to main process units and does not cover process auxiliaries. Also, only fire and explosion hazards are considered. Recently the index has been expanded to include business-interruption losses. The principles and general approach used in the Dow method of hazard evaluation have been further developed by Mond in the United Kingdom to include toxicity hazards. This revised Mond index is described in a paper by Lewis ... 

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