Mass explosion
In the case of explosives, a mass explosion is an explosion in which an entire charge is converted almost at the same time.
Explosives , i.e. those that explode with a higher than the speed of sound in the medium (one speaks of detonation ), are generally difficult to ignite. On the other hand, pyrotechnics with a lower conversion speed (one speaks of deflagration or burn-up ) tend not to have a mass explosion hazard: If one of the charges ignites the other, separate charges move one after the other so that no common pressure wave builds up. This difference is referred to by the concept of explosive substance being explosive. However, if too large quantities are dammed together or, under certain circumstances, only stored , a mass explosion can also occur in the case of pyrotechnic means and objects. In the case of pure black powder , this limit to mass explosiveness is around 1 kg, for example. The effect arises because this explosive substance is blocked by its own weight.
A mass explosion is particularly relevant to safety because the compact shock wave of a mass explosion has a strong splinter and heat effect. Non-mass explosive events also lead to splinters and litter, but remain smaller and tend to only lead to local fires. A mass explosion is similar to a detonation: In the case of an explosive, neighboring explosives are ignited by the pressure wave itself, and all the pressures add up, while the slower burn-up with pyrotechnic devices tends to distribute the charges before they ignite: This is referred to as a pushing explosion effect . Fireworks therefore work by dispersing the pyrotechnic effects widely and only then ignite the effects. Damming serves to build up higher pressures (loosely scattered black powder, for example, only burns rather slowly), therefore it promotes the joint implementation in the individual object, on the other hand it also prevents neighboring explosive objects from igniting. Mass explosiveness is therefore primarily an issue in the storage and transport of loose explosive substances, or bundles of ammunition or fireworks items, and mostly relates to entire stacks of boxes and packages or container contents (where the container itself acts as a further containment), up to entire shiploads, bunkers or production facilities. While explosives are usually only explosive in combination with an explosive detonator , fuels react to heat, black powder only to pressure, impact, as well as chemical instabilities, and the latter is therefore particularly unpredictable, especially when mixed with other chemicals. Overall, mass exposure is therefore not only a question of the chemical-physical properties of the material, but especially of storage and transport logistics.
Risk of mass explosion must be determined in individual tests. For this purpose, a certain storage is usually exposed to a fire , the most common cause of accidents, and one observes to what extent neighboring storage is infected and the extent of the explosion. The sign of a mass explosion is, for example, a crater and scattering of the containment material, otherwise measurements of the pressure surge effect are also necessary. Typically, individual package tests and stack tests are carried out, whereby a detection plate below the test arrangement can also be checked for damage (e.g. lead plate sample ). Thus, guidelines are developed, which articles must be as packed and stored together, to minimize or eliminate, such as through additional overpacks or air spacings between objects (those around the mass explosion risk shock effect of the pressure wave decreases roughly with the square of the distance, even slight gaps in the decimeter can have a positive effect).
The mass explosiveness of a substance-packaging combination is a decisive criterion in the classification of hazardous substances and dangerous goods . In Global Systems harmonized (GHS , combination of CLP, ADR and the like) is within the Hazard Class E [xpl.] 1 (2.1) respectively hazard classes 1 Explosive the security level 1, a mass explosion hazard ( H-set H201 explosive, mass explosion hazard , hazard classes 1.1 substances and objects that are capable of mass explosion , ERI card subclass 1-01) differentiated, non-mass explosive materials and storage have a correspondingly less dangerous classification (H202 ff and 1.2 ff). There is also danger level 5 (insensitive but mass explosive: H-phrase H205 risk of mass explosion in the event of fire , dangerous goods class 1.5 very insensitive mass explosive substances , ERI card 1-05 very insensitive explosive substances with the risk of a mass explosion ). Similar classifications can also be found in special systems such as the NATO ammunition fire classes .
1.1, for example, cartridges for weapons with explosive charges (explosive ammunition, UN number 0005, 0006), detonators (non-electrical UN 0029, electrical UN 0030) and explosive detonators (UN 0106), black powder (granular or in flour form UN 0027, pressed or as pellets UN 0028), pyrotechnic igniters ( ignition rods , UN 0121), distress signals (UN 0194), but also chemicals such as trinitrotoluene (TNT, <30% moisture) and tritonal (both UN 0390), or trinitrophenol (TNP, picric acid , <30% moisture, UN 0154). 1.5 is rare, for example with Ammonit C (UN 0331 explosives, type B), as it is used in avalanche explosions .
Individual evidence
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↑ Similar:
small symbol of the UN TDG (here 1.5); US DOT tunnel restriction (1.1)
- ↑ a b Definition according to the relevant labeling of hazardous substances / goods.
- ↑ Science - Armament - Peace: Basic Knowledge for Peace Research. VS Verlag für Sozialwissenschaften, 2007, ISBN 978-3-531-15057-4 , pp. 183-184, ( Google Books , accessed March 6, 2017).
- ↑ a b c d e Josef Köhler, Rudolf Meyer, Axel Homburg: Explosivstoffe. 10th edition. Publishing house John Wiley & Sons, 2012, ISBN 978-3-527-66007-0 , entry mass-explosive, mass-explosive. P. 142 ( Google Books , accessed March 10, 2017).
- ↑ a b c d UN test 6 (a) single package test , UN test 6 (b) stack test , UN test 6 (c) external fire test. Federal Institute for Materials Research and Testing (BAM), Technical Safety Test Site (tts.bam.de): Tests .
- ↑ See Bundeswehr and NATO Armed Forces. Ratingen fire brigade (accessed March 10, 2017).
