A detonator, frequently a blasting cap, is a small sensitive device used to detonate a larger, more powerful but relatively insensitive secondary explosive of an explosive device used in commercial mining, excavation, demolition etc.
Blasting Cap
A detonator, frequently a blasting cap, is a small sensitive device used to detonate a larger, more powerful but relatively insensitive secondary explosive of an explosive device used in commercial mining, excavation, demolition etc.
Blasting Cap
Blasting caps come in a variety of types, depending on the way they are initiated (chemically, mechanically, or electrically) and details of their inner working, which often involve several stages. They including non-electric caps, electric caps, and fuse caps, the last two being the most common. Electric types are set off by a short burst of current sent to the cap, by a blasting machine via a long wire or a radio controlled source to ensure safety. Traditional fuse caps have a fuse which is ignited by a flame source, such as a match or a lighter.
The need for detonators such as blasting caps came from the development of safer explosives, that would not explode if accidentally dropped, mishandled, or exposed to fire or electric fields. This required them to have high activation energy to detonate, and in turn made them correspondingly difficult to detonate intentionally. There come on stage the detonator, with the role to provide the required activation energy with a small initiating explosion. As a small device, it is easy to safely store and handle, and, while still hazardous, would do little damage even if it accidentaly fired. The detonator and the main explosive device can be kept separated, and only joined just before use, keeping the main charge safe.
Explosives commonly used as primary in detonators include lead azide, lead styphnate, tetryl, and DDNP.Early blasting caps also used silver fulminate, but it has been replaced with cheaper and safer primary explosives. Silver azide is still used sometimes, but very rarely due to its high price.
A non-electric detonator is a shock tube detonator designed to initiate explosions, generally for the purpose of demolition of buildings and for use in the blasting of rock in mines and quarries. Instead of electric wires, a hollow plastic tube delivers the firing impulse to the detonator, making it immune to most of the hazards associated with stray electric current. It consists of a small diameter, three-layer plastic tube coated on the innermost wall with a reactive explosive compound, which, when ignited, propagates a low energy signal, similar to a dust explosion. The reaction travels at approximately 6,500 ft/s (2,000 m/s) along the length of the tubing with minimal disturbance outside of the tube. Non-electric detonators were invented by the Swedish company Nitro Nobel in the 1960s and 1970s, and launched to the demolitions market in 1973.
In civil mining, electronic detonators have a better precision for delays. Electronic detonators are designed to provide the precise control necessary to produce accurate and consistent blasting results in a variety of blasting applications in the mining, quarrying, and construction industries. Electronic detonators may be programmed in millisecond or sub-millisecond increments using a dedicated programming device.
A number 8 test blasting cap is one containing 2 grams of a mixture of 80 percent mercury fulminate and 20 percent potassium chlorate, or a blasting cap of equivalent strength. An equivalent strength cap comprises 0.40-0.45 grams of PETN base charge pressed in an aluminum shell with bottom thickness not to exceed to 0.03 of an inch, to a specific gravity of not less than 1.4 g/cc, and primed with standard weights of primer depending on the manufacturer.[1]
The primary hazard of pyrotechnic blasting caps is that for proper usage, the fuse must be inserted and then crimped into place by crushing the base of the cap around the fuse. If the tool used to crimp the cap is used too close to the explosives, the primary explosive compound can detonate during crimping. A common hazardous practice is crimping caps with one's teeth; an accidental detonation can cause serious injury to the mouth.
Fuse type blasting caps are still in active use today. They are the safest type to use around certain types of electromagnetic interference, and they have a built in time delay as the fuse burns down.
Solid pack electric blasting caps use a thin bridgewire in direct contact (hence solid pack) with a primary explosive, which is heated by electric current and causes the detonation of the primary explosive. That primary explosive then detonates a larger charge of secondary explosive.
Match type blasting caps use an electric match (insulating sheet with electrodes on both sides, a thin bridgewire soldered across the sides, all dipped in ignition and output mixes) to initiate the primary explosive, rather than direct contact between the bridgewire and the primary explosive. The match can be manufactured separately from the rest of the cap and only assembled at the end of the process.
The first blasting cap or detonator was demonstrated in 1745 when British physician and apothecary William Watson showed that the electric spark of a friction machine could ignite black powder, by way of igniting a flammable substance mixed in with the black powder.[2]
In 1750, Benjamin Franklin in Philadelphia made a commercial blasting cap consisting of a paper tube full of black powder, with wires leading in both sides and wadding sealing up the ends. The two wires came close but did not touch, so a large electric spark discharge between the two wires would fire the cap.[3]
In 1832, a hot wire detonator was produced by American chemist Robert Hare, although attempts along similar lines had earlier been attempted by the Italians Volta and Cavallo.[4] Hare constructed his blasting cap by passing a multistrand wire through a charge of gunpowder inside a tin tube; he had cut all but one fine strand of the multistrand wire so that the fine strand would serve as the hot bridgewire. When a strong current from a large battery (which he called a "deflagrator" or "calorimotor") was passed through the fine strand, it became incandescent and ignited the charge of gunpowder.[5][6]
Smith also invented the first satisfactory portable power supply for igniting blasting caps: a high-voltage magneto that was driven by a rack and pinion, which in turn was driven by a T-handle that was pushed downwards.[13]
Blasting agent. Blasting agent - any material or mixture, consisting of a fuel and oxidizer, intended for blasting, not otherwise classified as an explosive and in which none of the ingredients are classified as an explosive, provided that the finished product, as mixed and packaged for use or shipment, cannot be detonated by means of a No. 8 test blasting cap when unconfined.
Class A explosives. Possessing, detonating, or otherwise maximum hazard; such as dynamite, nitroglycerin, picric acid, lead azide, fulminate of mercury, black powder, blasting caps, and detonating primers.
Water gels or slurry explosives. These comprise a wide variety of materials used for blasting. They all contain substantial proportions of water and high proportions of ammonium nitrate, some of which is in solution in the water. Two broad classes of water gels are
General hazard. No person shall store, handle, or transport explosives or blasting agents when such storage, handling, and transportation of explosives or blasting agents constitutes an undue hazard to life.
General. Unless otherwise set forth in this paragraph, blasting agents, excluding water gels, shall be transported, stored, and used in the same manner as explosives. Water gels are covered in paragraph (h) of this section.
The hauling of either blasting caps or other explosives but not both, shall be permitted on bulk trucks provided that a special wood or nonferrous-lined container is installed for the explosives. Such blasting caps or other explosives shall be in DOT-specified shipping containers: see 49 CFR chapter I.
Bins containing blasting agent shall be located, with respect to inhabited buildings, passenger railroads, and public highways, in accordance with Table-21 and separation from other blasting agent storage and explosives storage shall be in conformity with Table H-22.
General provisions. Unless otherwise set forth in this paragraph, water gels shall be transported, stored and used in the same manner as explosives or blasting agents in accordance with the classification of the product.
Water gels containing no substance in itself classified as an explosive and which are not cap-sensitive as defined in paragraph (a) of this section under Blasting Agent shall be classified as blasting agents and manufactured, transported, stored, and used as specified for "blasting agents" in this section.
The hauling of either blasting caps or other explosives, but not both, shall be permitted on bulk trucks provided that a special wood or nonferrous-lined container is installed for the explosives. Such blasting caps or other explosives shall be in DOT-specified shipping containers; see 49 CFR chapter I.
This section applies to the manufacture, keeping, having, storage, sale, transportation, and use of explosives, blasting agents, and pyrotechnics. The section does not apply to the sale and use (public display) of pyrotechnics, commonly known as fireworks, nor the use of explosives in the form prescribed by the official U.S. Pharmacopeia.
DSA offers a wide variety of individual, inert blasting caps and other assorted items for training purposes which perfectly simulate the visual appearance, tactility, and X-ray correctness of those used in real improvised explosive devices.
Suicide is a deliberate act of ending one's life. Suicide by use of any explosive device, when not involved in a terrorist act, is quite rare in occurrence when compared with other methods routinely utilized. In this paper, we present to the medicolegal community a case of an adult male who committed suicide with blasting caps and the subsequent extensive damage to the cranial hard tissue. Although the cause and manner of death were relatively straightforward, consultation with forensic anthropologists was requested for an anthropological trauma assessment of the highly fragmented skull. After the skull was cleaned and reconstructed, the analysis revealed similarities between blasting cap trauma to the head and high velocity gunshot trauma to the head. Therefore, in a case where some evidence may have been removed or destroyed, forensic analysis involving trauma of this magnitude could result in a misinterpretation of the true mechanism responsible for the osseous damage. In this case, cooperation among the law enforcement agency, coroner's investigators, the forensic pathologist, and forensic anthropologists provided a comprehensive death case analysis.
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