Initiation by percussion

Initiation by ignition) 291 (Initiation by percussion) 294 (Initiation by detonation and detonators) 318 (Igniter pad in separate-loading ammunition) 331 (Safety fuse) 332 (Squibs) 332 (Blasting caps) ... 

Primer Initiating device Initiated by percussion, stabbing, electrical current, heat, etc. 

Beryllium Diazide (formerly called Beryllium Trinitride), Be(Ns)j mw 93 07, N 90.31% wh solid, sol in tetrahydrofuran, insol in eth and easily hydrolyzed by w(Ref 1). Obtd by Wiberg Michaud (Ref 4) when Me,Be was sublimed and reacted with a dry eth soln of excess HNS at -116°. Removal of eth and excess HNS by vac distn yielded Be(N,),. In a reactn betw a beryllium salt and an azide, Curtius Rissom (Refs 1 2) obtd an impure beryllium azide it detonated only si in a flame and is insensitive to initiation by percussion (Ref3)... 

In the Journal de physique for 1779 the apothecary, Bayen, described a fulminating mercurial preparation of another kind. Thirty parts of precipitated, yellow oxide of mercury, washed and dried, was mixed with 4 or 5 parts of sulfur the mixture exploded with violence when struck with a heavy hammer or when heated on an iron plate. Other mixtures which react explosively when initiated by percussion have been studied more recently,2 metallic sodium or potassium in contact with the oxide or the chloride of silver or of mercury or in contact with chloroform or carbon tetrachloride. 

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... 

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. 

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... 

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... 

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)... 

Fuze, Impact. A fuze designed to be initiated by the force of impact (Compare with Fuze, Contact Fuze, Friction Fuze Percussion and Fuze, Stab)... 

Uses Can be used in detonators when initiated by another primary expl and functioning as an intermediate booster or when mixed with another primary exp to increase the sensitivity of the latter to flame or heat. Its mixture with LA was patented by Dynamit AG (Ref 8) for use in explosive rivets. Tetracene can also be used in primer caps where as little as 2% in the compn results in improved uniformity of percussion sensitivity... 

The expl props, as detd by Haid et al (Ref 8), indicate that Ca azide is the most powerful of the alkaline earth azides. Although Curtius found that this salt did not expl by percussion, Wohler Martin (Ref 5) and Haid et al (Ref 8) obtained deton by impact (Refs 7 12). When heated rapidly Ca(Nj)3 expl between 144-156°. Heated in a capillary tube, metallic Ca appears at 120-130° (Ref 11) and in vacuo expl between 160-170° (Ref 14). The kinetics of the thermal decompn has been studied by Andreev (Ref 10), Garner Reeves (Ref 19) and others ionic conductance of the solid by Jacobs Tompkins (Ref 18) in the temp range 290-370°K, and initiation and propogation of expln by Bowden Williams (Ref 16) who measured the rate of deton as 770 m/sec. 

Delay-Relay Element. It is a component of HE train which introduces a delay in the time of functioning of the fuze. The delay element is always followed by a relay and the two are really one unit. The relay is an expl (such as BkPdr) designed to provide continuity of the expl train by picking up the weak flash from the delay element and augmenting it sufficiently to initiate, by detonation, a succeding component. The delay-relay element is located in the fuze of a projectile betw the percussion primer and the detonator (Ref 1)... 

The anhydrous salt explodes on impact [1], and decomposes violently at 200°C [2]. The trihydrate is also percussion sensitive [3] though other sources suggest that in clean, grease- and oil-free equipment the anhydrous salt is shockproof [4]. A bottle of the purified anhydrous salt exploded then burnt on opening, (transition to sodium chloride and oxygen has an enthalpy of 1.2 kJ/g), presumably initiated by friction in... 

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 [1]. Precautions recommended include use of cold zinc and total enclosure of such processes [2]. The possibility of explosions of zinc dust suspended in air is presented as a serious hazard [3]. A serious dust explosion in the air filter unit of a zinc grinding mill was initiated by a spark from an explosion relief panel [4]. 

Properties They are high explosives and are characterized by relatively great sensitivity to beat or shock. They detonate when subjected to heat or shock and are set off by the spit of a black-powder fuse, by the heat of an electrically heated wire, by percussion (firing pin), or by friction. Their detonation produces flame and shock, which are used to initiate the deflagration of powder or the detonation of high explosives. ... 

Detonation, as described earlier, is a process where upon a matrix of uniform particles of gas and solid forms a pressure wave. The pressure wave is what causes the bulk of destruction. However, it should be noted that detonation is a completely different process then deflagration and combustion. As previously stated, compounds that detonate must poses certain functional groups. These functional groups are initiated by molecular shocks generated by blasting caps, detonators, and/or boosters. Of coarse not all explosives need to be initiated by blasting caps, detonators, and/or boosters for example, primary explosives (which you will learn much about shortly) can be detonated under relatively easy means by sparks, heat, friction, percussion, fire, and shock. 

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