Shock sensitivity is a comparative measure of the sensitivity to sudden compression (by impact or blast) of an
explosive
An explosive (or explosive material) is a reactive substance that contains a great amount of potential energy that can produce an explosion if released suddenly, usually accompanied by the production of light, heat, sound, and pressure. An ex ...
chemical compound
A chemical compound is a chemical substance composed of many identical molecules (or molecular entities) containing atoms from more than one chemical element held together by chemical bonds. A molecule consisting of atoms of only one element ...
. Determination of the shock sensitivity of a material intended for practical use is one important aspect of
safety testing of explosives.
A variety of tests and indices are in use, of which one of the more common is the Rotter Impact Test,
with results expressed as FoI (
Figure of Insensitivity.) In addition, various "gap tests" are used to measure sensitivity to blast shock.
Sensitivities vary widely
A few materials such as
nitrogen triiodide cannot be touched at all without
detonating, and so are of purely academic interest. Some other compounds with a high sensitivity to shock, such as
nitroglycerin
Nitroglycerin (NG) (alternative spelling nitroglycerine), also known as trinitroglycerol (TNG), nitro, glyceryl trinitrate (GTN), or 1,2,3-trinitroxypropane, is a dense, colorless or pale yellow, oily, explosive liquid most commonly produced by ...
and
acetone peroxide, may detonate from a firm jolt and so cannot be legally transported in pure form. Acetone peroxide is often used by amateurs and terrorists as a means to detonate other explosives as well as acting as the main blasting agent, often resulting in injuries or death to those who underestimate its sensitivity. A number of methods are known to desensitize nitroglycerine so that it can be transported for
medical uses, and it is also incorporated into other less sensitive explosives, such as
dynamite
Dynamite is an explosive made of nitroglycerin, sorbents (such as powdered shells or clay), and Stabilizer (chemistry), stabilizers. It was invented by the Swedish people, Swedish chemist and engineer Alfred Nobel in Geesthacht, Northern German ...
s and
gelignite
Gelignite (), also known as blasting gelatin or simply "jelly", is an explosive material consisting of collodion-cotton (a type of nitrocellulose or guncotton) dissolved in either nitroglycerine or nitroglycol and mixed with wood pulp and Potassi ...
s.
Many practical commercial materials of intermediate sensitivity, such as gelignites and
water gel explosives, can be safely handled as they will not explode from casual shocks such as being dropped or lightly knocked by a tool. However, they may explode if struck forcefully by a metal tool, and would certainly explode in the barrel if they were used in an artillery
shell
Shell may refer to:
Architecture and design
* Shell (structure), a thin structure
** Concrete shell, a thin shell of concrete, usually with no interior columns or exterior buttresses
Science Biology
* Seashell, a hard outer layer of a marine ani ...
. Reliable initiation of such materials requires the small explosion of a
detonator. Apart from this another explosive material such as
Armstrong's mixture is also used in commercial markets and even sold to the public in the form of
fireworks
Fireworks are Explosive, low explosive Pyrotechnics, pyrotechnic devices used for aesthetic and entertainment purposes. They are most commonly used in fireworks displays (also called a fireworks show or pyrotechnics), combining a large numbe ...
,
cap guns and
party poppers.
See also
*
Activation energy
*
Catastrophic failure
A catastrophic failure is a sudden and total failure from which recovery is impossible. Catastrophic failures often lead to cascading systems failure. The term is most commonly used for structural failures, but has often been extended to many ot ...
*
Phase change
References
Explosives
{{explosive-stub