Fire and Explosive Properties

Fires and explosions are the large-scale accidents most to be feared in the typical process plant. For diorough coverage of the vital topic of protection from these hazards, the reader should consult the large body of specialized literature. The National Fire Protection Association (NFPA), the publisher of the National Fire Codes, provides good summaries of codes and safe practices. 

Some of the NFPA Standards consulted during preparation of this volume are listed in the Bibliography. A consolidated source is the NFPA s Flammable and Combustible Liquids Code Handbook. A more specialized discussion of bvdlding exits and fire escapes is in the Life Safety Code Handbook. 

The fuel element of the fire/explosion triad can be any flammable material. Degree of flammability is indicated by a material s explosive or flammable limits, its flash point, and its autoignition temperature. These, with other combustion properties, are documented in the standard references previously noted. 

Oxygen for combustion is present in air, but other chemical oxidizers such as halogens, nitric add, nitrogen oxides, and peroxides may be present. Certain materials (e.g., ethylene oxide) contain internal oxygen which increases sensitivity and can take part in the combustion reaction. 

The source of ignition can be an open flame, a spark, a hot surface, static electricity, or autoignition. Plant personnel must strive to eliminate all ignition sources from locations where flammable materials are stored or handled or must institute procedtues to control the resulting hazards. 

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Fire and explosion properties are not fundamentally based and are an artifact of a particular experimental apparatus and procedure. 

There are many reasons for fires and explosions in a process plant. They result from a chemical reaction where a combustible material reacts with oxygen and heat is released. Fire and explosion properties of materials were already dealt with in Chap. 2. 

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. 

Physical Properties of Monomers. 1-Butene [106-98-9] is a colorless, flammable, noncorrosive gas its physical properties are fisted in Table 1, and its thermodynamic properties are available (16). Because 1-butene has a very low flash point, it poses a strong fire and explosion hazard. 

The next simplest ether is the ether with the simplest alkane as one of the hydrocarbon backbones and the next alkane, which is methyl ethyl ether. Its molecular formula is CH3OC2H5. It is a colorless gas with the characteristic ether odor. It has a flash point of 31 °F, and an ignition temperature of only 374°F. This property, of course, makes it an extreme fire and explosion hazard. 

Complete and accurate written documentation of chemicals properties, process teclinology, and process equipment is essential to the PSM program and to a process hazards analysis (PrHA). This information serves many users including the PrHA team. The needed chemical information includes fire and explosion characteristics, reactivity hazards, safety and health hazards and the corrosion and erosion effects. Current material safety data sheet (MSDS ) information helps meet this requirement, but must be supplemented with process chemistry information regarding runaway reactions, and over-pressure hazards. 

Tlie remainder of tliis cliapter provides information on relative physical properties of materials (flash points, upper and lower explosive limits, tlireshold limit values, etc.) and metliods to calculate tlie conditions tliat approach or are conducive to liazardous levels. Fire liazards in industrial plants are covered in Sections 7.2 and 7.3, and Sections 7.4 and 7.5 focus on accidental explosions. Sections 7.6 and 7.7 address toxic emissions and liazardous spills respectively. tliese latter types of accident frequently result in fires and explosions tliey can cause deatlis, serious injuries and financial losses. 

Effect models describe the impact of the physical effects of a fire, e.xplosion, or toxic gas release on exposed people, the environment or property, based on the results of tlie source, dispersion, and fire and explosion models. 

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. 

Chemical and hydrocarbon plant losses resulting from fires and explosions are substantial, with yearly property losses in the United States estimated at almost 300 million (1997 dollars).1 Additional losses in life and business interruptions are also substantial. To prevent accidents resulting from fires and explosions, engineers must be familiar with... 

When considering the use of equipment for detecting and suppressing fires and explosions, munitions manufacturing processes are among the most hazardous. In these applications, little time is available for the system to respond. A reaction time that is only a few milliseconds too slow could result in extensive property damage and even loss of life. 

Accident statistics have shown that fires and explosions represent 97 percent of the largest accidents in the chemical industry (J. Coco, ed., Large Property Damage Losses in the Hydrocarbon-Chemical Industry A Thirty Year Review, J. H. Marsh and McLennan, New York, 1997). 

The following is a brief selective listing of major worldwide fire and explosion incidents within the hydrocarbon and chemical industries during the last 25 years (1970 - 1994), both onshore and offshore. Numerous smaller incidents have been recorded that are not listed here but may be studied in other references. Where the number of fatalities has been reported in public accounts they are listed next to the financial loss. Financial losses are direct property damage losses and do not include business interruption, legal, or environmental impacts. 

Safety of Reactive Chemicals and Pyrotechnics (Yoshida et al. 1995). Addresses both the hazardous properties of reactive chemicals and appropriate handling methods. Describes several test methods and the evaluation of fire and explosion hazards of reactive substances, including the impact of initiating events such as earthquakes. 

U.S. Fire Administration NFIRS Response data submitted by local fire departments 1980-Present Includes fire and explosion incidents with no/little release, incidents resulting in property damage only, and near-misses if fire department was called Limited state participation Represents limited information available to fire department at time of response Checklist approach limits respondent choices Not designed to be a lessons-learned database... 

The purpose of layout and spacing is to design a workplace that will minimize personnel injuries, overall property damage, and related business interruption resulting from potential toxic releases, fires, and explosions. Areas to address during layout and spacing include both those that will minimize the incident size and those that will minimize the incident impact. The magnitude of a potential incident may be reduced by ... 

Toxicity is the ability of a substance to cause injury to biological tissue. The hazard or risk of a substance is the probability that it will cause injury in a given environment or situation. The hazard of a substance depends on several factors, including its toxicity how it is absorbed, metabolized, and excreted how rapidly it acts its warning properties and its potential for fire and explosion. 

This book is split into six well-defined chapters Salient Features of Explosives, Status of Explosives, Processing and Assessment of Explosives, Propellants, Pyrotechnics, and Explosive and Chemical Safety. Further, the book includes an exhaustive bibliography at the end of each chapter (total references cited are more than 1000). It also provides the status of HEMs reported mainly during the last 50 years, including their prospects for military applications in the light of their physical, chemical, thermal and explosive properties. The likely development areas for further research are also highlighted. Accidents, fires and explosions in the explosive and chemical industries may be eliminated or minimized if the safety measures described in this book are implemented. 

A.H.Nuckolls, UnderwritersLablnc, Bull of Research 39(1947)(The comparative explosion hazards of AN coated with organic matter) 90)G.S.Scott R.L. Grant, US BurMines Circ 7463(1948)(AN, its properties and fire and explosion hazards) 91)A.Robertson, JSCI 67,221-4(1948) CA 43,405 (1949) (Thermal decompn of AN and other explosives)... 

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