Meyer R., Koehler J., Homburg A. Explosives. Wiley-VCH, 2002 / Explosives 5th ed by Koehler, Meyer, and Homburg (2002)

Seismometer, Falling Pin

An instrument used to indicate relative intensity of ground vibration. It consists of a level glass plate on which a series of 1//4c diameter steel pins (6c to 15c lengths) stand upright inside of metal tubes. The use of the falling pin seismometer is based on the theory that the length of the pin toppled depends upon the amount of ground vibration present.

Seismopak

Trade name of explosives in layflat charges used in seismic prospecting for surface shooting in combination with Dynacord. Both products are manufactured and distributed by DYNAMIT NOBEL, Troisdorf, Germany.

Seismoplast 1

Trade name of a plastic, water-resistant cap-sensitive explosive used for seismic exploration under extreme conditions such as pressures up to 500 bar and temperatures as low as – 40 °C. Manufactured and distributed by DYNAMIT NOBEL, Troisdorf, Germany.

Semigelatin Dynamites

Semigelatin dynamites are so named because of their consistency. These so-called semigelatins contain ammonium nitrate and wood meal as their main Components, and also 10–14% of a weakly gelatinized nitroglycerine.

Semtex

Trade name of a plastic explosive (W Plastic Explosives) from the Czechoslovakian firm Synthesia, Pardubice-Semtin.

Semtex consists of W Pentaerythritol Tetranitrate and styrene-buta- diene copolymer as a plasticizer.

set forward

Relative forward movement of component parts which occurs in a projectile, missile, or bomb in flight when impact occurs. The effect due to inertia and is opposite in direction to setback.

Shaped Charges

Hollow Charges; Hohlladung; charge creuse (W also Munroe Effect)

A shaped charge is an explosive charge with a hollow space facing the target.

A rotationally symmetric shaped charge is an explosive charge with an axis of symmetry which acts preferentially in the direction of the rotational axis. Shaped charges lined in a rotationally symmetric manner can pierce steel sheets eight times as thick as the diameter of the charge.

Liners for shaped charges are made of inert material, usually a metal. The lining acts as an energy carrier, since the energy of the explosive charge is concentrated on a small cross-section of the target.

The detonation of the explosive charge causes the lining material to collapse and to converge in the axis of symmetry of the charge. During this process the colliding metal mass separates into a large mass portion moving slowly and a smaller mass portion moving forward at very high speed. Only the fast moving portion with its high kinetic energy produces the perforation effect in the target: It forms a jet of very small diameter and correspondingly high density of energy. The slow moving portion is left as a conglomerated molten slug after detonation.

The main parameters to characterise a lined shaped charge are the detonation velocity, the density of the explosive, the geometry of the detonation wave, the shape of the lining, the lining material and its wall thickness.

Cutting charge

A plane-symmetrical shaped charge (cutting charge) is an explosive charge with a hollow space, which acts longitudinally in the plane of symmetry (“roof-shaped” charges).

Plane charge

In a plane charge the opening angle of the conical liner is larger than 100°. When the explosive is detonated, the lining no longer converges into a jet in the axis of symmetry, so that no jet or slug can be formed out of the collapse point; rather, the lining is turned inside out. The

resulting sting is much thicker and much shorter with a weaker perforating power, but a larger perforation diameter than that made by a shaped charge.

Projectile-forming charge; self-forging fragment;

EFP (explosively formed projectile)

In a projectile-forming charge, the geometry of the lining is such that all its elements have approximately the same velocity. The strength of the material is chosen so that it can easily absorb the residual differences in the velocities. In this way a projectile with a greater kinetic energy is obtained, which consist, roughly speaking, of the entire mass of the lining, and which can also be employed against distant targets.

The shaped-charge effect was first described in 1883. Shortly before the Second World War, Thomanek found that the piercing power of the shaped charge could be significantly increased by lining the hollow space.

The first theoretical treatment of the subject was by Trinks in 1943/44 in a report submitted by the Research Department of the German Army Weapons Command.

The first non-classified study on the subject was that by Birkhoff Mac Dougall, Pugh and Taylor: Explosives with Lined Cavities, J. Appl. Physics. Vol. 19, p. 563 (1948).

For the first non-classified study concerning an interpretation of jet extension and the attendant increase in the duration of the effect, see Pugh, Eichelberger and Rostoker: Theory of Jet Formation by Charges with Lined Conical Cavities. J. Appl. Physics, Vol. 23, pp. 532–536 (1952).

Sheathed Explosives

ummantelte Sprengstoffe; explosifs gaines´

Permitted explosives which are enveloped in a special cooling “sheath”; they are now obsolete.

High-safety explosives, such as sheathed explosives, whose structure is nevertheless homogeneous, are known as “explosives equivalent to sheathed” (Eq. S.); W Permissibles.

Silver carbide is very sensitive to impact. It is prepared by bubbling acetylene through a slightly acidic or neutral silver nitrate solution.

Silver Azide

Silberazid; azoture dargent

AgN3

molecular weight: 149.9 nitrogen content: 28.03%

volume of detonation gases: 224 l/kg density: 5.1 g/cm3

melting point: 251 °C = 484 °F lead block test: 115 cm3/10 g deflagration point: 273 °C = 523 °F

Silver azide is sensitive to light, insoluble in water, and soluble in ammonia, from which it can be recrystallized. It is prepared from sodium azide and solutions of silver salts (depending on the working conditions) as a cheesy, amorphous precipitate.

It gives a very satisfactory initiating effect which is superior to that of lead azide. Nevertheless, its practical use is limited, because of its high sensitivity to friction, and because its particular texture makes the dosing difficult.

Silvered Vessel Test

In this testing procedure to propellant sample (about 50 g) is heated in a insulating Dewar vessel, and the rise in temperature produced by the heat of decomposition of the powder is determined. The powder sample is heated to 80 °C (176 °F); the time is determined in which the powder reaches 82 °C (180 °F) by its own heat development on decomposition.

Frey’s variant of the silvered vessel test has been in use in the Germany In its variant, different amounts of heat are supplied to the electric heating elements mounted inside the Dewar flask, and the temperature differences between the interior of the Dewar vessel and the furnace are measured by thermocouples. A calibration curve is plotted from the values thus obtained, and the heat of decomposition of the propellant is read off the curve. In this way, the decomposition temperature at a constant storage temperature can be determined as a function of the storage time, and the heat of decomposition of the propellants can thus be compared with each other. If the measurements are performed at different storage temperatures, the tempera-

ture coefficient of the decomposition rate can be calculated. (W also

Differential Thermal Analysis.)

Silver Fulminate

Knallsilber; fulminate dargent

CNOAg

white, crystalline powder molecular weight: 149.9 oxygen balance: –10.7% nitrogen content: 9.34%

Silver fulminate is prepared by the reaction employed in the preparation of W Mercury Fulminate, i.e., by reacting a solution of silver in nitric acid with alcohol. Like mercury fulminate, it is also toxic.

Silver fulminate is much more sensitive than mercury fulminate. Since its detonation development distance is very short, its initiation effect is superior to that of mercury fulminate, but the compound is too sensitive to be used commercially.

An altogether different product, known as Berthollet’s detonating silver (which is not a fulminate), is obtained when a solution of freshly precipitated silver oxide in ammonia is allowed to evaporate. Its probable formula is Ag3N. It is highly sensitive and explodes even during the evaporation of the ammoniacal solution.

Single Base Powders

Nitrocellulose-Pulver; poudre a` simple base

Such powders mainly consist of nitrocellulose and stabilizers as well as other additives such as dinitrotoluene in some formulations. Nitrocellulose is gelatinized with the aid of solvents, mostly etheralcohol mixtures, and additives are incorporated and gelatinized by prolonged kneading. The mixture is shaped into tubes, perforated tubes, flakes, etc., by extrusion and cutting, and the solvents are removed by evaporation, displacement by warm water, vacuum drying, etc., and the material is surface-treated. The purpose of the surface treatment is to let phlegmatization agents diffuse into the material, thus retarding the combustion rate in the surface layers and to attain a progressive burning rate (W Progressive Burning Powders).

SINCO® Ignition booster and gas mixture for motor vehicle safety

SINCO® was developed by the Dynamit Nobel GmbH Company as an environmentally compatible and particularly stable class of substances for rapid gas evolution. It involves a pyrotechnic gas mixture based on nitrogen-rich fuels and oxygen carriers as reactants. A solid combustion residue consisting essentially of alkali carbonates, nontoxic gas products consisting of nitrogen, water vapour, carbon dioxide and oxygen together with heat are liberated during the reaction between fuels and the oxygen carriers.

The gas mixtures themselves are free from heavy metals and have high toxicological compatibility. In the acute oral toxicity test carried out according to the EU Directive, the LD50 value was greater than 2500 mg/kg.

In addition the pyrotechnic mixtures are characterised by high thermal stability. This is also necessary in order to guarantee a constant reaction characteristic over a long period of time and even after thermal stressing.

Stable reaction of the mixtures is possible only with tamping. This property reduces the potential risk that may occur in the event of improper handling or possible misuse.

Because of its properties, SINCO® is suitable for personal protection in passive safety systems in motor vehicles. In addition to the use of SINCO® in pressure elements for seat-belt tensioners or lock tensioners, the gas mixture is also suitable for driver and passenger gas generators. In this case the mixture also performs the function of a booster charge in the igniter elements of the gas generators in addition to the main task of gas evolution.

The proportion of solids formed, which can be controlled via the composition of the mixture, promotes the process of tablet ignition in the gas generator combustion chamber.

SINOXID Primer Composition

SINOXID is the trademark used for the traditional primer compositions of DYNAMIT NOBEL AG. The formulation was developed by Rathsburg and Herz and patented as tetracenetricinate primer composition in 1928.

The term SINOXID is made up of “sine” and “oxide” and means “without rust”. It underlines the fact that this composition is not susceptible to corrosion as against mercury fulminte – potassium chlorate mixtures. SINOXID compositions consist of the following components: