Initiation explosive train

Accdg to definition given in Ref 23, p 3-22 (slightly reworded) It is an initiating explosive - train component fired by an electrical impulse supplied by the energy either stored within the fuze before release of the missile, or generated within the fuze system just prior to or at impact of the fuze. An electric primer serves to initiate the next component of the train which can be either a detonator or delay element... 

Explosive train Arrangement of explosive components in which the initial force from the primer is transmitted and intensified until it reaches and sets off the main explosive composition. 

Detonators are used to detonate high explosives. Stab detonators are initiated by sharp firing pins and are used in explosive trains of different types of fuses. Flash detonators are initiated by flames produced by safety fuses, primers, or delay elements. A special type of flash detonator ignited by the flame of a safety fuse is called a blasting cap. Detonators are primarily composed of three types of explosives including sinoxid mixtures, lead azide-based mixtures, and mercury fulminate-based mixtures. 

An explosive device is initiated or detonated by an explosive train — an arrangement of explosive components by which the initial force from the primary explosive is transmitted and intensified until it reaches and sets off the main explosive composition. Most explosive trains contain a primary explosive as the first component. The second component in the train will depend on the type of initiation process required for the main explosive composition. If the main explosive composition is to be detonated, the second component of the train will burn to detonation so that it imparts a shockwave to the main composition. This type of explosive train is known as a detonator. Detonators can be initiated by electrical means, friction, flash, or percussion. 

If an explosive train is only required to ignite a main composition, an igniter that produces a flash instead of a detonation is used. Explosives of this kind are known as deflagrating explosives. Similar to detonators, igniters can be initiated by electrical means, friction, flash, or percussion. An example of an igniter is a squib, a small explosive device loaded with an explosive that deflagrates. Its output is primarily heat.8... 

Explosives are classed as primary or secondary. Typically, a small quantity of a primary explosive would be used in a detonator (known colloquially as a cap ), whereas larger quantities of secondary explosives are used in the booster and the main charge of a device. This collection of explosives is known as an explosive train in which a signal (mechanical, thermal, or electrical) from the control system is converted first into a small explosive shock from the detonator, which in turn initiates a more powerful explosion in the booster, which amplifies the shock into the main charge. 

The requirement for an explosive train, that is, a primary explosive to initiate the secondary explosive, is a safety feature. In the past, people wishing to illegally use explosives usually had to steal the detonators (e.g., Timothy McVey). Consequently, the effective control of access to detonators has been widely regarded as a key pubhc safety measure by many governments and law enforcement agencies. However, recently, triacetone triperoxide (TATP) has been used as the primary explosive (e.g., Richard Reid s shoe bomb) and TATP is readily, although hazardously, synthesized from acetone, hydrogen peroxide, and acid. 

INITIATOR The first component in a pyrotechnic or explosive train. 

Detonation (and Explosion) by Priming and Boostering. These are means of building up a detonation from an initiating shock (Ref 2, p 294). The detonator, the first element in an explosive train or "explosive chain , may have three parts. 

Initiating Agent. An explosive material which has the necessary sensitivity to heat, friction, or percussion to make it suitable for use as an initial element in dn explosive train (Ref 40a, p 92)... 

Pistol (British). A mechanical device used since WWI, which is designed to initiate an explosive train by either freeing or functioning a striker but which contains no explosive itself. It is comparable in its mechanical function with US fuzes... 

Relay. A component of a high-explosive train that provides the required energy to reliably initiate the next element in the train. Specifically applied to small charges that are initiated by a delay element and, in turn cause the functioning of a detonator (Ref 40a, p 120)(See slso in this Volume, Section 4, Part F (Compare with Lead)... 

According to definition given by Ohart (Ref 17, p 55), such a detonator is "an explosive component for initiation of detonation in an explosive train or transmitting a primer im-... 

Definition of a relay as given by Odierno of PicArsn (Ref 45d, p I) is An element of a fuze explosive train which augments an outside and otherwise inadequate output of a prior explosive component so as to reliably initiate succeeding train component. Relays, in general, contain a small single charge such... 

Fuze, Mine. A fuze designed to initiate a train of fire in a land mine. For initiation of underwater (sea) mine a device known as "Firing Mechanism, Underwater Mine" It is a device contg combustible or explosive components, which can be actuated by an acoustic signal, impact, hydrostatic pressure, and/or magnetic influence (Ref 40a, pp 71... 

Ohart(1946), 12 45 (Primers, defini. tion) 19-20 (The explosive train) 35 (Initiators, definition) 46 (Primer mixtures) ... 

Explosive train A series of combustible or explosive components arranged in order of decreasing sensitivity designed to initiate explosives. 

Fuze A mechanical, chemical, or electrical device designed to initiate an explosive train. 

Initiator The part of an explosive train that starts the reaction. 

Explosive Train Test. See Ref 81 in Vol 4, pp D345-L D345-R. It is an abstract of description given in TM 9-1300-214/XO-11 A-1-34 (1967), under the title "Initiating Value Test"... 

Fuze Handbook, Up-dated The engineering textbook on fuze design is arranged in three parts (1) Fundamental principles (covers purposes, general functioning, design considerations, initiation, and explosive train)... 

Military explosives comprise explosives and explosive compositions or formulations that are used in military munitions (bombs, shells, torpedoes, grenades, missile or rocket warheads). The bulk charges (secondary explosives) in these munitions are insensitive to some extent and are, therefore, safe for handling, storage and transportation. They are set off by means of an explosive train consisting of an initiator followed by intermediates or boosters. 

Pyrocartridges (also known as electrical initiators) are used to initiate the explosive train for specific applications in rockets and missiles. The pyrocartridges contain broadly the following ingredients or explosives. 

The detonator is considered as the first fire-device of key importance in any explosive train and contains a small quantity of a very sensitive explosive as a means of initiation of inorganic salts of weak acids, that is, M F, LA and LS. However, they all suffer from some shortcoming and are not eco-friendly. In order to overcome these shortcomings of the existing initiatories, use of nickel hydrazine nitrate (NHN) [ Ni(N2H4)3 (N03)2], which has better storage stability and is also eco-friendly, has been reported in the literature [262, 263]. 

An explosive composition is initiated or detonated via an explosive train. The explosive train is an arrangement of explosive components by which the initial force from the primer is transmitted and intensified until it reaches and sets off the main explosive composition. Some components of explosive trains are summarized in Table 4.5. 

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