High Explosive Charges

Initiation of High Explosive Charges In practice, high explosive charge can be initiated 

During production, storage, transport, and similar activities, explosives are frequently exposed to various external stimuli such as fiiction, impact, heat, etc. The ability of an explosive to react to these stimuli, resulting in either combustion or detonation, is (tefined as its sensitivity. This particular property of explosives might be a key ctor in determining the practical applic ility of a given explosive. 

The energy required for the initiation of reactions of decomposition can be applied in the form of 

The application of heat in the initiation of explosives can be realised in two ways 

Suceska, Test Methods for Explosives Springer Science+Business Media New York 1995 

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The predetonation distance (the distance the decomposition flame travels before it becomes a detonation) depends primarily on the pressure and pipe diameter when acetylene in a long pipe is ignited by a thermal, nonshock source. Figure 2 shows reported experimental data for quiescent, room temperature acetylene in closed, horizontal pipes substantially longer than the predetonation distance (44,46,52,56,58,64,66,67). The predetonation distance may be much less if the gas is in turbulent flow or if the ignition source is a high explosive charge. 

The above procedure produces blast parameters applicable to a completely symmetrical blast wave, such as would result from the explosion of a hemispherical vessel placed directly on the ground. In practice, vessels are either spherical or cylindrical, and placed at some height above the ground. This influences blast parameters. To adjust for these geometry effects, and 7 are multiplied by some adjustment factors derived from experiments with high-explosive charges of various shapes. 

Primer. High explosive charge used to initiate other high explosive. 

Electric detonators are also used for detonation of high explosive charges. They are similar in design to other types of detonators except for the presence of an electric fusehead consisting of a bridgewire made of chromium and nickel. The bridgewire is covered by a heat-sensitive pyrotechnic mixture protected by varnish insulation. Standard fuseheads have electrical resistance of 1.2 to 1.4 ohms and... 

Cutting of Metal Plates with High Explosive Charges is discussed by W.H. Drummond in jApplMech 25, 184-88(1958)... 

Primers used for nonmilitary (commercial or industrial) purposes are devices which initiate high explosive charges (such as Dynamites) by shock produced on detonation of primary charges and not by a flash or flame as in the case of igniters... 

Base charge The main high explosive charge in a blasting cap. 

Cyclonite intended for high explosive charges should pass through a 0.75 mm mesh sieve. Cyclonite for caps and detonators should pass through a 0.60 mm. mesh sieve. 

Prior to 1831, straws filled with blackpowder, or fuses, which were cords saturated with a powder mixture, were used for igniting high explosive charges. The rate of burning of these powder timetrains was very irregular and lead to a great many accidents due to premature explosions. In 1831, a considerable advance was made... 

Nitromannite is about as sensitive as nitroglycerin to shock and to friction. It detonates under a 4-cm. drop of a 2-kilogram weight, and may be exploded readily on a concrete surface by a blow of a carpenter s hammer. It is not fired by the spit of a fuse, but is made to detonate by the flame of a match which causes local overheating. It is almost, but not quite, a primary explosive. It is used as the high-explosive charge in compound detonators which contain the relatively safe diazodinitrophenol as the primary explosive. A mixture of nitromannite and tetra-cene is a powerful and brisant primary explosive which detonates from moderate heat. 

Cutting of Metal Piotes with High Explosive Charges in analyzed discussed by W.E. Drummond, jApplMechanics 25, 184-88 (1958)... 

Hydrodynamic test facilities capable of handling the detonation of high explosive charges of 1 kg or greater and suitable for use of appropriate diagnostic instrumentation. 

Detonating cords contain high explosives and are used to detonate high explosive charges from a safe distance. The first detonating cord syn. detonating fuse was the Cordeau detonant cord, a lead tube filled with a TNT core... 

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