Explosion

See also: Explosion (homonymy)

A explosion is the fast transformation of a Matière into another matter having a larger volume, generally in the form of Gaz.
The more quickly this transformation is carried out, the more the resulting matter is in overpressure; while slackening until balance with the atmospheric pressure, it creates a breath deflagrating or exploding, according to its speed.

Classification

The explosions can be classified according to the speed of the wave which they generate:

  • one employs the term Déflagration when the face of decomposition moves at a speed lower than the Speed of sound in the local medium,
  • one speaks about Détonation when the face of flame exceeds the speed of sound, which generates a Shock wave. It is what occurs during the use of a Détonateur or a Explosif breaking, the face of decomposition can be propagated at speeds which exceed 10 km/s.

Causes

An explosion can result from a Chemical reaction: the Volume occupied by gases produced by the reaction is higher than the volume of the reagents:

  • the reagents solid S (for example Poudre) or liquids are thus more dense that the produced gases;
  • the reagents can be also gases, but the quantity of gas produced (number of mole S) is higher than the initial quantity of gas;
  • if the reaction is exothermic, the Chaleur causes a Dilatation gases of reaction.
An explosion can also result from a very violent Vaporisation, as in the case of the boiling-explosion or Bleve ; it is then about a physical transformation, a change of phase.

Traumatology

There are four effects of an explosion on the man:

  • the blast : it is a Barotraumatisme, i.e. a traumatism created by the overpressure of the air; it includes in particular:
    • the blast of the tympanum S, being able to go to the tear of the tympanums: Deafness momentary or final, Acouphène S;
    • the pulmonary blast : the shock wave strikes the chest and causes damage inside;
  • the consecutive Fall with the difference in pressure between the front (left vis-a-vis the explosion) and the back of overpressure;
  • projection of objects, remains ( Shrapnel S );
  • psychological shock.

There can also be a collapse of structure (building, wall), as well as burns in the case of a hot gas expansion or of an intense radiation.

Use

  • One uses the relaxation of gases to produce a work in the engine spark-ignition (deflagration) or the reaction engine .

  • One uses also the properties of fast transformation hyper of certain materials to manufacture Explosif S at ends of Civil engineering, military Engineering or to manufacture Munition S and Arme S.

See too

Internal bonds

External bonds

  • Explosion - three blast, E. Torres, M. - P. Rudelin, the General practitioner n°2 155, November 20th 2001

  • the blast, Lesions caused by an explosion, P. Naudin, K. Oualim, an article of the Urgency-practical site

Simple: Explosion

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