Percussion initiators

It is becoming increasingly clear that the preponderant amt of modern ordnance requiring the initiation of HE charges utilize electric initiation. However, there still remains a continued requirement for the use of percussion initiation. The use and description of sensitive artillery primers, eg, M29A1, etc, to accomplish this has previously been discussed... 

An initiating composition is coated on a wire centered in the tube, the wire acting as an anvil for this percussion initiating action. 

Mercury fulminate was first prepared in the 17th century by the Swedish-German alchemist, Baron Johann Kunkel von Lowenstern. He obtained this dangerous explosive by treating mercury with nitric acid and alcohol. At that time, Kunkel and other alchemists could not find a use for the explosive and the compound became forgotten until Edward Howard of England rediscovered it between 1799 and 1800. Howard examined the properties of mercury fulminate and proposed its use as a percussion initiator for blackpowder and in 1807 a Scottish Clergyman, Alexander Forsyth patented the device. 

One definition of a blank cartridge is a percussion initiated cartridge that does not have a bullet or missile that is designed to be lethal. However, blank cartridges are dangerous if misused and serious injuries and a few fatalities have resulted from their misuse at close range. (A dummy round is not a blank as it is completely inert.)... 

The silver salt has also been suggested for practical use in percussion-initiated devices such as heads of percussion fuses [72]. This salt has recently been proposed as a potential green primary explosive that could replace LA. A potential drawback, however, of AgNT is its high sensitivity to electrostatic discharge [52]. 

AN 76, N.S.N. 10, K nitrate 10, K perchlorate 2 resin 2% (2) Explosives patented by Distier, Blecher and Lopez (Refs 2 3) (a) AN 88 N.S.N. 12%. It is insensitive to shock or percussion and does not explode when heated to 200° or when ignited in an open flame, but detonates with considerable brisance when strongly initiated. The brisance may be reduced by substituting either K nitrate or Amm perchlorate for part of the AN. (b) AN 85,... 

Percussion. The act of striking one body against another with a sharp blow. As some expls, such as MF or LSt are very sensitive to such a blow (shock or impact), they may be expld (or ignited) by such action. In this case, the term percussion can be applied to initiation or priming by such action, as weil as to the expln (or deflagration or ignition) caused by percussion... 

MECHANICAL initiators PERCUSSION PRIMERS, STAB DETONATORS, AND FRICTION PRIMERS... 

Although it is evident that initiators represent a broad spectrum of items and designs, both percussion and electric, the contents of this treatise will deal only with three selected types of percussion items ie, percussion primers, stab primers and/or detonators, and friction primers... 

The selection of a stab detonator for a specific application requires a consideration of both input and output (Ref 7). The situation exactly duplicates the problems encountered in the selection of a percussion primer. However, as previously discussed, the end purpose of a detonator is different the input energies are significantly lower, and the output is intended to initiate a high expl. In addition to the main criteria, consideration must also be given to size, weight, cost, and reliability... 

Tetryl is a pale yellow solid, melting at 129°C. It is moderately sensitive to initiation by friction or percussion. Tetryl is most used in the form of pressed pellets as primers for other less easily initiated explosives. 

Tetrazene is a light yellow crystalline substance, insoluble in water and most organic solvents. The density is low under normal conditions, but on pressing can reach approximately 1 g ml-1. Tetrazene is weak as an initiating explosive, and is therefore not used alone. It has no advantages to commend it for use in commercial detonators, but does find application in the manufacture of military and other percussion caps. Like diazodinitrophenol, tetrazene does not detonate when ignited in the open, but only when ignited under confinement. 

A cloud of zinc dust generated by sieving the hot dried material exploded violently, apparently after initiation by a spark from the percussive sieve-shaking mechanism... 

Detonator Device for initiating an explosive that requires a shock wave. Initiation may be via electrical means, friction, flash from another igniferous element, stabbing, or percussion. A detonator may be constructed to detonate instantaneously or may contain a delay element. 

Tetryl (C7H5N508) is a pale yellow crystalline solid. It is moderately sensitive to initiation by friction and percussion and is used in the form of pressed pellets as primers for explosive compositions that are less sensitive to initiation. It is slightly more sensitive than picric acid and considerably more sensitive than TNT. In the early 1900s, tetryl was used as base charges for blasting caps but now has been replaced by PETN and RDX. During World War II, tetryl was used as a component of explosive 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... 

It becomes a problem in semantics to set a time limit for "development within which a process can be considered "spontaneous or "instantaneous . These two words seem to apply well to such extremely sensitive compounds as Nitrogen Triodide and Cupric Azide, which explode at the slightest touch when dry and, in addition, explode at a fairly low temperature. Attempts to correlate initiation in such cases with the attainment of a certain temperature seem unrealistic, especially in view of differences between relative sensitivity of different compounds to mechanical and thermal influences. For example, Mercuric Azide is so sensitive to impact that it explodes even under water, hut its heat sensitiveness is about the same as that for Cadmium Azide, which has been reported not to explode by percussion (Ref 5) Information about susceptibility of different explosives to spontaneous detonation is highly important from the viewpoint of safety. In Refs which follow are listed examples of spontaneous detonations of substances, some of them previously considered safe in this respect... 

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)... 

The most important improvement in the initiation of BkPdr was, however, the development of the percussion principle, which was... 

Accdg to Ref 37, pp 3 6, the ignition ttain for pyrotechnics begins with an initiator. usually a primer which may be of the percussion, friction, or electric type. The flame produced on initiation is transmitted successive-... 

Electric Primer MK34 Mod O is similar in construction to MK15 primer, except that it is designed for electrical initiation only and cannot be activated by percussion (Ref 52, p 2-129)... 

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