Explosive potential detonation parameters

VIII. Explosive Characteristics. Picric Acid is generally considered to be a relatively insensi tive but brisant expl. On a qualitative sensitivity scale of comparing common expls, PA would be judged to be more sensitive than TNT but appreciably less sensitive than Tetryl. Its power and brisance are also similar to those of TNT (112% TNT in the Ballistic Mortar 101% of TNT in the Trauzl Block and 107% in the plate dent test (Ref 48). In this section we will consider the steady detonation parameters. initiation characteristics and potential hazards of PA... 

In this context it should also be mentioned that 3,4-dinitropyrazole (DNP) is an interesting melt-cast explosive (m.p. 87 °C, Tdec. = 276 °C) which can easily be prepared from nitropyrazole (Fig. 2.9a). Due to the relatively high density of 1.79 g cm 3, DNP has good detonation parameters (VoD = 8115 m s 1, pc j = 294 kbar) and may therefore be a potential replacement for Comp. B (RDX/TNT, VoD = 7969 m s, pc j = 292 kbar). Therefore, DNP has great potential as a new melt-pour base. DNP (3,4-dinitropyrazole) is now technically mature, and has been consistently synthesized at BAE SYSTEMS on the 100-g scale with 65 % crude yield and 99.9 % HPLC purity but with 5 % remaining acids. 

Because precise measurement techniques have not been available to determine the response and performance of detonator elements, it is not possible to state unequivocally which parameters are most important for their most effective or optimum design. Potentially important parameters can, however, be derived from well-known principles that govern the behavior of solid explosives. 

However, the working potential of an explosive cannot possibly be expressed by means of a single thermochemical or detonation parameter of given explosive, such as heat liberated in chemical reactions or detonation velocity. The ability of a certain explosive to perform a defined kind of mechanical work is determined by several parameters the amount of gases formed in the reactions, the liberated heat, and the detonation velocity. Which one of these parameters will be the most important for a defined kind of work depends primarily on the condition under which the explosive process takes place. 

The principal feature of this relationship is that F values are derived solely from molecular formulae and chemical structures and require no prior knowledge of any physical, chemical or thermochemical properties other than the physical state of the explosive that is, explosive is a solid or a liquid [72]. Another parameter related to the molecular formulae of explosives is OB which has been used in some predictive schemes related to detonation velocity similar to the prediction of bri-sance, power and sensitivity of explosives [35, 73, 74]. Since OB is connected with both, energy available and potential end products, it is expected that detonation velocity is a function of OB. As a result of an exhaustive study, Martin etal. established a general relation that VOD increases as OB approaches to zero. The values of VOD calculated with the use of these equations for some explosives are given in the literature [75] and deviations between the calculated and experimental values are in the range of 0.46-4.0%. 

The performance potential of an explosive cannot be described by a single parameter. It is determined by the amount of gas liberated per unit weight, the energy evolved in the process (-> Heat of Explosion), and by the propagation rate of the explosive (detonation velocity -> Detonation). If an explosive is to be detonated in a borehole, the... 

The use of these empirical tests is necessary because of the inadequacy of data necessary for theory to provide a computational basis for determining the output parameters necessary to achieve initiation of a secondary explosive with lead azide. The foregoing sections indicate that even empirical data on the parameters that affect the azide output are fragmentary. Nevertheless, the theory can indicate potentially important conditions necessary for an optimum detonator, and a brief discussion of the status of the theory is given at the end of this section. 

The JCZ3 EOS was the first successful model based on a pair potential that was applied to detonation [11]. This EOS was based on fitting Monte Carlo simulation data to an analytic functional form. Hobbs and Baer [12] have recently reported a JCZ3 parameter set called JCZS. JCZS employs some of the parametrization techniques used in the construction of BKWC. It achieves better accuracy for the detonation of common high explosives than BKW equations of state. Since it is extensively parametrized to detonation, it has difficulty in reproducing reactive shock Hugoniots of hydrocarbons and other liquids [13]. 

If the ability of an explosive to create a strong shattering effect in the nearest vicinity of the explosive charge is considered, then the most important parameter for explosive working potential will be detonation velocity. The ability of an explosive to perform such mechanical work is called brisance ability. The word comes fi om briser, wiiich in French means to shatter, to fragment. Brisance ability is nminly a result of the strong cfynamic impact of the detonation products and shock wave into the surrounding medium. Therefore, it is fully of (tynamic-impulse nature. 

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