Detonation velocity
The detonation speed of an explosive is the speed of the reaction front with which the chemical reaction moves within the explosive, how quickly and suddenly it decomposes or reacts. The explosive's explosive potential is the product of the detonation speed, charge density and specific energy . A high detonation speed ensures that the pressure builds up suddenly and the energy stored in the chemical compounds is released in the shortest possible time.
While black powder (detonation speed 300 to 600 m / s) burns relatively slowly with the formation of large amounts of gas (at subsonic speed, one usually speaks of deflagration ), explosive explosives are converted at ten times the speed and more. This process is known as detonation . The reaction front forms a shock wave (see also detonation wave ).
In the case of slow explosives such as black powder , if pressure must first be built up through damming , which then suddenly releases its energy when the damming bursts, which can also be heard as a bang, this is in principle no longer necessary for explosives with a high detonation speed (higher than the speed of sound ) . Explosives that are less sensitive to pressure (e.g. TNT ) are nevertheless loaded in solid enclosures. Without this shell, an outer layer up to several millimeters thick would be detonated from the charge without detonating, which would reduce the effect.
Many organic explosives detonation velocity and may detonation pressure of about using Kamlet Jacobs equations are calculated.
A short table outlines the typical (maximum) detonation rates of some known explosives:
| Explosives designation | Detonation velocity (m / s) |
|---|---|
| Gunpowder | 300 to 600 |
| Ethine / oxygen | 2400 |
| Ammonium nitrate (NH 4 NO 3 ) | 2500 |
| Oxyhydrogen 2 H 2 + O 2 | 2820 |
| Chloratite 3 | 3350 |
| Lead azide | 4630 |
| HMTD ( hexamethylene triperoxide diamine ) | 4500 to 5100 |
| APEX ( acetone peroxide ) | 4500 to 5300 at a density of 0.9–1.2 g / cm³ (trimeric A.) |
| Cellulose nitrate | 6300 |
| Gelatin dynamite | 6350 |
| TNT ( trinitrotoluene ) | 6700 or 7028 |
| TNP ( picric acid ) | 7100 |
| TATB ( triaminotrinitrobenzene ) | 7600 |
| NGL ( nitroglycerin ) | ≈2500 to 7700; depending on the type of ignition and the damming, in some cases up to 9000 |
| PETN ( nitropenta ) | 5000 to 8340; depending on the loading density |
| RDX, C4, T4, Torpex ( Hexogen ) | 8400 |
| HMX ( Octogen ) | 9110 |
| HNIW ( Hexanitrohexaazaisowurtzitan (CL20) ) | 9380 or 10300 |
- ↑ the values can vary depending on the source
See also
- Burn rate - the corresponding value for stationary burns of explosives
literature
- DIN EN 13631-14 Explosives for civil purposes - High explosives, Part 14: Determination of the detonation rate
- Paul Hölemann: The measurement of flame and detonation speeds during the explosive decomposition of acetylene in pipes. Westdeutscher Verlag, Cologne and Opladen 1957.
- Henrikus Steen (ed.): Manual of explosion protection. Wiley-VCH, Weinheim 2000, ISBN 978-3-5272-9848-8 .
- Wilhelm Jost: Explosion and combustion processes in gases. Published by Julius Springer, Berlin 1939.
- Josef Köhler, Rudolf Meyer: Explosives. 9th revised and expanded edition, Wiley-VCH, Weinheim 1998, ISBN 3-527-28864-3 .
Web links
- Explosives (accessed February 13, 2020)
- Burning behavior of near-sound and supersonic-faster hydrogen-air flames (accessed on February 13, 2020)
- History of Explosives (accessed February 13, 2020)
- Investigations into gas detonations in capillaries for microreaction technology (accessed on February 13, 2020)
- Safety studies on microstructured reactors for heterogeneously catalyzed oxidation reactions in the explosion area (accessed on February 13, 2020)