Explosion imperfect

Preliminaries. The combustion of suspended dusts and powders is quite complex and only imperfectly understood. The complexity stems from both fundamental and practical considerations. On the fundamental side, the ignition of suspensions of finely divided solids is influenced by hard-to-quantify factors such as the time-varying concentration of solids, the chemical activity and morphology of the particulate, and the degree of confinement provided by the vessel. On the practical side, industrial conditions are seldom sufficiently well-controlled or characterized to justify application of existing theoretical models. For all the above reasons, this chapter can provide only a very abbreviated coverage of ignition basics. The reader is referred to other sources for in-depth treatment of dust and powder explosions (Bodurtha, 1980 Bartknecht, 1981 Bartknecht, 1987). 

In ideal combustion 0.45 kgs (1 lb.) of air combines with 1.8 kgs (4 lbs.) of oxygen to produce 1.2 kgs (2.75 lbs.) of carbon dioxide and 1.02 kgs (2.25 lbs.) of water vapor. Carbon monoxide, carbon dioxide, nitrogen and water vapor are the typical exhaust gases of ordinary combustion processes. If other materials are present they will also contribute to the exhaust gases forming other compounds, which in some cases can be highly toxic. Imperfect combustion will occur during accidental fires and explosion incidents. This mainly due to turbulence, lack of adequate oxidizer supplies and other factors that produce free carbon (i.e., smoke) particles, carbon monoxide, etc. 

When exposed to the atmosphere, sodium amide rapidly takes up moisture and carbon dioxide. When exposed to only limited amounts, as in imperfectly sealed containers, products are formed which render the resulting mixture highly explosive.1 The formation of oxidation products is accompanied by the development of a yellow or brownish color. If such a change is noticed, the substance should be destroyed at once. This is conveniently accomplished by covering with much benzene, toluene, or kerosene and slowly adding dilute alcohol with stirring. 

Gray and Waddington [57,120] examined the physico-chemical properties of silver azide and state that its melting point is 300°C. On the basis of the latest opinion that the explosive decomposition of azides results from processes involving ions and electrons caused by imperfection and deficiencies in the crystal lattice (Jacobs and Tompkins [22]), the authors incorporated silver cyanide, Ag2(CN)2,... 

Corner s Equation of State. At the high temps pressures encountered in explosives technology, the perfect gas law is not applicable. The calculation of pressures developed by expls therefore requires the adoption of a suitable equation of state. Furthermore, in calculating the explosion products it is necessary to correct the ideal thermodynamic equilibria of the relevant chem reactions for the effect of the gas imperfection. This correction also depends on the equation of state adopted. Most equations of state, whether empirical or theoretical, are not suitable for application at the high temps pressures developed by expls. Comer has recently discussed a theoretical equation of state applicable to propellent expls (Ref 3)... 

CA 51, 1610 (1957) (Imperfect character of the explosion, gases covolume of propints)... 

As for other explosives like RDX and HMX, the impact sensitivity depends not only upon the molecular structure but also crystal morphology and imperfections. There is no study that maps the relation between morphology and sensitivity for ADN. However, as can be seen above, the 2 kg impact sensitivity is decreased from 31 cm to 59 cm when ADN is prilled. On the other hand, another study shows the same sensitivity for prilled and neat ADN [16]. 

A few years ago the concept considered was introduced also in the low-temperature chemistry of the solid.31 Benderskii et al. have employed the idea of self-activation of a matrix due to the feedback between the chemical reaction and the state of stress in the frozen sample to explain the so called explosion during cooling observed by them in the photolyzed MCH + Cl2 system. The model proposed in refs. 31,48,49 is unfortunately not quite concrete, because it includes an abstract quantity called by the authors the excess free energy of internal stresses. No means of measuring this quantity or estimating its numerical values are proposed. Neither do the authors discuss the connection between this characteristic and the imperfections of a solid matrix. Moreover, they have to introduce into the model a heat-balance equation to specify the feedback, although they proceed from the nonthermal mechanisms of selfactivation of reactants at low temperatures. Nevertheless, the essence of their concept is clear and can be formulated phenomenologically as follows the... 

Furnaces are comparatively simple items for a plant, and because they are unsophisticated they tend to he imperfectly understood by operators and plant managers alike. Their tolerance to abuse is limited, and once abused their useful life can be drastically shortened. Worse still they may fail suddenly, since furnace tubes disten t easily and then fracture. Such failure is often severe, with a consequential fire and/or explosion. 

Slow neutron irradiation caused color changes and darkening in most of the explosive crystals, indicating the formation of imperfections, which subsequently affected the thermal decomposition of the explosives. The rates of thermal decomposition of irradiated lead azide are shown in Figure 9. 

The use of IR microscopy is still fairly new but appears to be a technique that will find increasing applications in the future. Some of its current applications include identification of polymer contaminants, imperfections in polymer films, and individual layers of laminated polymer sheets identification of tiny samples of fibers, paint, and explosives in criminalistics characterization of single fibers in the textile industry and identification of contaminants on electronic components. 

The next two types of EOS represent a more practical a posteriori approach to C-J calculations. The form of the EOS for an imperfect gas is assumed, and parameters appearing in it are adjusted to reproduce (for a few prototype explosives) experimental D-po curves, and sometimes also C-J pressures. C-J calculations are then performed on related explosives in the hope of achieving good agreement with experimental values. 

There are other factors for the production of toxic/poisonous composition/ compounds. Imperfect explosion condition, noncomplete detonation, or blasting of explosive leads to production of large amount of NO2. The posttreatment of... 

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