Potential energy, explosives

Other. Because a foam consists of many small, trapped gas bubbles, it can be very effective as a thermal insulator. Usually soHd foams are used for insulation purposes, but there are some instances where Hquid foams also find uses for insulation (see Eoamed plastics Insulation, thermal). Eor example, it is possible to apply and remove the insulation simply by forming or coUapsing the foam, providing additional control of the insulation process. Another novel use that is being explored is the potential of absorbing much of the pressure produced by an explosion. The energy in the shock wave is first partially absorbed by breaking the bubbles into very small droplets, and then further absorbed as the droplets are evaporated (53). 

Dicyanogen is extremely endothermic (AH°f (g) +307.9 kJ/mol, 5.91 kJ/g) and the potential energy of mixtures with powerful oxidants may be released explosively under appropriate circumstances. 

Energy of explosion. The energy of explosion values given in Table 16.2 should be considered as the theoretical maxima, and yield factors of 10% are considered reasonable for fuel-air explosions. For equivalent volume storage, hydrogen has the least theoretical explosive potential of the three fuels considered, albeit it has the highest heat of combustion and explosive potential on a mass basis. 

In each of these plants, the characterization of the dust explosion potential was carried out by sampling transport ducts for explosive dust concentrations during an actual plant operation. The critical measurements taken were the quantification of explosive dust concentrations and level of electric energy generated from the electrostatic charge accumulations found in the duct. 

Pressure is an indicator of potential energy which affects the leak rates in the case of loss of containment. Higher pressures also pose stricter requirements to the strength of vessels. Leaks in vacuum equipment may cause inlet of air and consequent explosion. 

Detonation (and Explosion), Available Energy. See under "Detonation (and Explosion), Power, Available Energy (or Maximum Available Work Potential) and Strength in ... 

Greenet (Ref 1, p 565) defined it as "a thermodynamic machine by which the potential energy of the explosive is converted into the kinetic energy of the projectile . Although he does not describe in his book any artillery pieces, the meaning of his definition is that... 

An explosive is a substance or device which produces, upon release of its potential energy, a sudden outburst of gases thereby exerting high pressure on its surroundings. 

In other words, investigation of explosives involves a study of these aspects. For example, an investigation of the potential energy involves study of thermochemistry of the chemical compound in question. Further, the power and sensitiveness of an explosive depend on properties such as heat of formation and heat of explosion . An investigation of the feature (2) involves measurement of the rate of propagation of explosion waves and all phenomena in the proximity of detonating mass of the explosive. This rate of decomposition largely determines the pressure... 

The potential energy of an explosive depends on (1) The volume of gas generated—calculated for purposes of comparison purposes at 760 mm. and 0° and (2) on the temp, developed on explosion, whereby the gases are expanded enormously. A. Noble and F. Abel estimate the total work theoretically performable is 332,000 gram-metres per gram, or 486 foot-tons per lb. of powder. 

A physical explosion can arise when a substance whilst being compressed undergoes a rapid physical transformation. At the same time, the potential energy of the substance is rapidly transformed into kinetic energy, and its temperature rises rapidly, resulting in the production of a shockwave in the surrounding medium. 

Danger of Handling Explosives. Any compd or mixt which may be potentially expl should be regarded with suspicion and handled with more than usual care. Such a compd or mixt is one whose heat of formation (AQ =-AHf) is smaller by more than 100-200 cal/g than the sum of the heats of formation of its products. When any doubt exists about an expl system, its potential energy can often be calcd... 

The material factor (MF) is the basic starting value in computation of the F EI and other risk analysis values. It is a measure of the intrinsic rate of potential energy release from fire or explosion produced by combustion or other chemical reaction. The MF is obtained from Ns and Nr, NPFA signals expressing flammability and reactivity (or instability), respectively. The values for many materials are found in NFPA 325M or NFPA 49. Dow has developed values for additional materials and published them as an appendix of the F EI Guide. ... 

During oxidation of a sulfide to a sulfoxide, it was found that the peracid, in DMF, was dangerously unstable. It was shown it could convert to the dibenzoylperoxide, probably of lesser reactivity, thus permitting a build-up of potential energy during a semi-batch process. However, the explosion seems to have occurred in the reagent solution, not yet added to the sulfide. Peroxide formation might provide an explanation for the earlier incident reported below, but seems less satisfactory here. Like other formates, DMF is a reducant. Replacement of DMF by dichloromethane permitted scale-up. 

There is an account of an incident involving combustion/explosion in the free space of a weak ammonia liquor tank where detailed examination revealed no evidence for an ignition source [5]. The existence of ammonia—air mixtures able to bum only in sufficiently large enclosed volumes was established [6], Previous data on flammability has been summarised and extended by determination of flammability characteristics of ammonia admixed with dry air and oxygen-deficient air at temperatures from ambient up to 400°C. Similar work with added water vapour at 80°C shows that aqueous solutions of below 5% ammonia content do not produce flammable vapours at any temperature, and that above 49°C no flammable vapours are produced by ammonia solution of any concentration. Some data on ignition energy and explosibility are also given [7], Two US incidents serve as a reminder of the considerable explosive potential of ammonia—air mixtures in confined volumes. An... 

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