Mechanical chemical explosions

Chapter 3 Explosives Dehnition of Explosion Categories of Explosions Phases of Explosions Mechanical Overpressure Explosions Mechanical/Chemical Explosions Chemical Explosions Dust Explosions Nuclear Explosions Components of an Explosion Types of Explosives... 

Explosion is burning that takes place sonically, hence, a shock front is produced. The damage mechanisms are physical destruction from the shock wave, collateral damage from falling structures, and human bums. Suffocation and poisoning are not usually associated with an explosion because of its short duration. A chemical explosives such as nitroglycerine, trinitrotoluene, dynamite, and others were discussed in Section 7.2.6. 

The blast wave resulting from a chemical explosion is generated by the rapid expansion of gases at the explosion site. This expansion can be caused by two mechanisms (1) thermal heating of the reaction products and (2) the change in the total number of moles by reaction. 

With proper initiation, chemical explosives (as opposed to mechanical or atomic explosives) undergo violent decomposition to produce heat, gas, and rapid expansion of matter. 

Besides physical (which includes mechanical and electrical and chemical explosions, there is also atomic (or nuclear) explosion, already described in Vol 1, p A501-R (Ref 8)... 

Fuze A mechanical, chemical, or electrical device designed to initiate an explosive train. 

This chapter has so far described the total chemical energy released when a chemical explosion takes place. This energy is released in the form of kinetic energy and heat over a very short time, i.e. microseconds. In a detonating explosive a supersonic wave is established near to the initiation point and travels through the medium of the explosive, sustained by the exothermic decomposition of the explosive material behind it. On reaching the periphery of the explosive material the detonation wave passes into the surrounding medium, and exerts on it a sudden, intense pressure, equivalent to a violent mechanical blow. If the medium is a solid, i.e. rock or stone, the violent mechanical blow will cause multiple cracks to form in the rock. This effect is known as brisance which is directly related to the detonation pressure in the shockwave front. 

This book outlines the basic principles needed to understand the mechanism of explosions by chemical explosives. The history, theory and chemical types of explosives are introduced, providing the reader with information on the physical parameters of primary and secondary explosives. Thermodynamics, enthalpy, free energy and gas equations are covered together with examples of calculations, leading to the power and temperature of explosions. A very brief introduction to propellants and pyrotechnics is given, more information on these types of explosives should be found from other sources. This second edition introduces the subject of Insensitive Munitions (IM) and the concept of explosive waste recovery. Developments in explosive crystals and formulations have also been updated. This book is aimed primarily at A level students and new graduates who have not previously studied explosive materials, but it should prove useful to others as well. I hope that the more experienced chemist in the explosives industry looking for concise information on the subject will also find this book useful. 

Chemical kinetics explains how reactions occur by studying their rates and mechanisms. Chemical kinetics explains how the speeds of different chemical reactions vary from explosive rapidity to glacial sluggishness and how slow reactions can be accelerated by materials called catalysts. Chemical kinetics has enormous practical importance because it provides the basis for optimizing conditions to carry out chemical reactions at reasonable speed, under proper control. 

The term explosion is best defined as a process that involves a sudden release of energy resulting in a rapid and significant buildup of overpressure. Explosions can be categorized into physical/mechanical and chemical explosions. For example, an explosion caused by a sudden release of compressed gas is a physical explosion. A chemical explosion is caused by a chemical reaction(s), which could be combustion, exothermic decomposition or exothermic reaction. Chemical explosions can occur in gas, liquid or solid phase. Chemical explosions that occur in liquid and solid phases are sometimes called condensed phase explosions. Explosive explosions fall in this category. 

Other appUcstions of themiodynaoiics considered in this book include how chemicals distribute when released to the environment, determining.safety by estimating the possible impact (or energy release) of mechanical and chemical explosions, the analysis of biochemical processes, and product design, that is. identifying a chemical or mixture that has the properties needed for a specific application. 

In Sec. 5.3 we considered the thermodynamics of explosions that did not involve chemical reaction. Here, we extend this discussion to explosions with chemical reaction. Since the energy released on an exothermic reaction may be very large, chemical explosions are generally more devastating than purely mechanical explosions. In a... 

The equations describing a chemical explosion are the same as those for a mechanical explosion (see Sec. 5.3) that is, to compute the maximum energy released in an explosion, we assume the process within the region bounded by the shock wave is reversible and adiabatic so that... 

According to the NFPA Fire Protection Handbook, there are two general categories of explosions, physical and chemical. In a physical explosion, the high-pressure gas is produced by mechanical means, i.e., even if chemicals are present in the container, they are not affected chemically by the explosion. In a chemical explosion, the high-pressure gas is generated by the chemical reaction that takes place. 

Normally, a chemical explosive of any type should explode when heated or subjected to mechanical impact. The terms heat and shock refer to mild-to-moderate heating and slight shock or jarring, respectively. 

Li Y, Ma S (1992) Mechanics of explosion. Science Press, Beijing Liu J (1987) Basic chemical explosives. Guiyang... 

Design deficiencies that render the incineration system unable to overcome the difficulties caused by thermal, mechanical, chemical or radiological failures Introduction of materials into the waste feed that lead to excessive temperatures, overpressurization and/or explosive conditions within the incineration... 

Explosives and fuze safety is the process used to prevent premature, unintentional, or unauthorized initiation of explosives and devices containing explosives and to minimize the effects of explosions, combustion, toxicity, and any other deleterious effects. Explosives safety includes all mechanical, chemical, biological, electrical, and environmental hazards associated with explosives or EM environmental effects. Equipment, systems, or procedures and processes whose malfunction would cause unacceptable mishap risk to manufacturing, handling, transportation, maintenance, storage, release, testing, delivery, firing, or disposal of explosives are also included. 

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