Instantaneous detonators

There have been a lot of accidents caused by the ignition of ammonia in oxygen. If ammonia is in the liquid state, the mixture can instantaneously detonate. 

There was a rather surprising instantaneous detonation when making an aluminium oxide/sodium nitrate mixture. 

P3. Class of Permitted Explosives for general use with instantaneous detonators. 

The chemical reactions involved are of the electron-transfer, or oxidation-reduction, type. The compounds and mixtures to be studied are almost always solids and are designed to function in the absence of external oxygen. The reaction rates to be dealt with range along a continuum from very slow burning to "instantaneous" detonations with rates greater than a kilometer per second (Table 1. 1). 

II. Explosives for coal work (explosifs couche). They may be used only with instantaneous detonators. The minimum initial charge is 500 g in coal and 1000 g in rock. 

FID fuze, instantaneous detonating FNMAL Fabrica Nacional de Munifoes de... 

Expls utilized in gassy or dusty coal mines are divided into a)Explosifs couche and b)Explosifs couche ameliores. The former may only be fired with instantaneous detonators and their charge limit is 500g for shots in coal layer and lOOOg for shots in rock. 

Lasers have been used to initiate deton in RDX. Three types of initiation mechanisms have been described (Ref 102) (1) instantaneous deton caused by a shock wave in a thin metallic film (deposited on the expl) with the shock wave generated by a Q-switched laser pulse (2) instantaneous deton by direct interaction of a Q switched laser pulse and the test expl and (3) DDT produced by free-running laser pulses. Coarse RDX cannot be initiated, but milled RDX (particle size less than 40 microns) is readily initiated at various packing densities. The threshold fluences for the initiation of 1.18g/cc l,52g/cc milled RDX via mechanism (1) are 45,3J/cm2 and 127.9J/cm2, respectively. Detons are either essentially instantaneous or the sample bums without deton. For direct initiation [mechanism (2)], the threshold laser energy for 1.18g/cc RDX was 0.8J, or the same as in thin film initiation. However, deton was no longer instantaneous but required about 2 microsec for build-up. The 1.52g/cc RDX was initiated directly without delay (laser energy not given)... 

Detonation is a chemical reaction given by an explosive substance in which produces a shock wave. High temperature and pressure gradients are generated in the wave front, so that the chemical reaction is initiated instantaneously. Detonation velocities lie in the approximate range of 1500 to 9000 m/s = 5000 to 30000 ft/s slower explosive reactions, which are propagated by thermal conduction and radiation, are known as -> Deflagration. 

For instantaneous detonation of booby-trap grenades,tape a plastic soda straw on the fuse tube and fill it loosely with match-head material,dosing the end with a plug of Kleenex or cotton. To prevent confusion, shorten the safety levers of the modified grenades. 

A study of the initiation of lead azide by the impact of flyer plates (Section F) showed that stress excursions behind the shock front produce pressure waves which travel through the shock-compressed azide at a velocity at least equal to the sonic velocity. The sonic velocity in the precompressed explosive is higher than in the uncompressed explosive, so the amplitude of the initial shock increases rapidly until steady-state detonation is achieved in less than 1 mm, as indicated by the data in Table IV. For an initial stress over 4 kbar, instantaneous detonation occurred however, pressures this high are not normally present at the input to the azide in an explosive train. 

The short-pulse initiation threshold for PVA lead azide was 4.2 kbar for a density of 3.6 g/ml, and for dextrinated lead azide was 2.1 kbar at a density of 2.7 g/ml. Almost instantaneous detonation was noted above 6.2 kbar for PVA lead azide, while even at 8 kbar dextrinated lead azide displayed a 0.2-psec delay. 

The second group, the so-called lead azide group, does not exhibit a predetonation zone under normal conditions. Initiation by flame results in practically instantaneous detonation. The typical members of this group include, besides lead azide, also silver fulminate and silver azide. Explosives of both groups—MF group as well as LA group—detonate when initiated by shock wave [24]. 

Photo 4.3 Common grenade fnse assembly (white metal). The tnbe in the center is the fuse train. It can be cut off. Each %-inch segment is one second less time. No fuse train equals instantaneous detonation (i.e. for a trip wire). 

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