Explosions propagation

Dust explosions usually occur in pairs. The first explosion involves dust already in suspension. This jars dust from beams, ledges, etc, creating a second cloud to which the explosion propagates, resulting in a secondary explosion. Dust clouds have been ignited by open flames, electric sparks, hot... 

Particularly reasonably priced explosion isolation of systems involves the use of a relief pipe with which the flow direction can be diverted by 180°. It prevents flame jet ignition with precompression in constructionally protected equipment. If suction is present, explosion propagation can occur. To prevent this, the use of an additional extin-gui ing barrier or a rapid-action gate valve is necessary. If a diverter is installed where positive pressure feed is given, then the diverter is, in general, safe against an explosion propagation. 

Reactivity (instability) information Acceleration rate calorimetry Differential thermal analysis (DTA) Impact test Thermal stability Lead block test Explosion propagation with detonation Drop weight test Thermal decomposition test Influence test Self-acceleration temperature Card gap test (under confinement) JANAE Critical diameter Pyrophoricity... 

Hjertager, B. H., M. Bjorkhaug, and K. Fuhre. 1988b. Explosion propagation of non-homogeneous methane-air clouds inside an obstructed 50m vented vessel. J. Haz. Mat. 19 139-153. 

Although the status of many 3D codes makes it possible to carry out detailed scenario calculations, further work is needed. This is particularly so for 1) development and verification of the porosity/distributed resistance model for explosion propagation in high density obstacle fields 2) improvement of the turbulent combustion model, and 3) development of a model for deflagration to detonation transition. More data are needed to enable verification of the model in high density geometries. This is particularly needed for onshore process plant geometries. 

Hjertager, B. H., T. Solberg, and K. O. Nymoen. 1991a. Computer modeling of gas explosion propagation in offshore modules. 

Analytical Model to Predict Explosion Propagation Between Adjoining Explosive Items , PATR 4722 (1974) 24) Anon, Moderniza-... 

Explosion Propagation of a flame in a premixture of combustible gases, suspended dust(s), combustible vapor(s), mist(s), or mixtures thereof, in a gaseous oxidant such as air, in a closed or substantially closed vessel. 

For the explosion protection valves always two installation distances are to be indicated, namely, the minimum and maximum installation distances. The minimum installation distance ensures that the given isolation system can react in time to prevent an explosion propagation beyond the installation place. The maximum installation distance ensures that a detonation in the piping cannot be formed up to the isolation system and/or that excessive pressure loads are avoided at the isolation system. 

Detonation (and Explosion), Propagation Through Explosive Charges. In addn to information and references given under "Detonation (and Explosion), Initiation (Birth) and Propagation (Growth or Spread) in Explosive Substances , following refs should be consulted ... 

Detonation (and Explosion), Propagation Through Layers of Non-explosive Substances Between Explosive Pellets. This problem was investigated at the USBurMines and reported by C.M. Mason et al, Progress Rept Oct-Dec 1950. A brief description of this work is given under " Detonation (and Explosion) by Influence, 1 Ref 12 Note The non-explosive layers between explosive charges are known as barriers... 

Detonation (and Explosion), Transmission of. Same as Detonation (and Explosion), Propagation of... 

Explosion Propagation Thru Layers of Nonexplosive Substances. See Vol 4, p D498-R... 

Mixtures with nitrobenzene were formerly used as liquid high explosives, with addition of carbon disulfide to lower the freezing point, but high sensitivity to mechanical stimulus was disadvantageous [1]. During the recovery of acids from nitration of toluene, mixtures of the oxide with nitrotoluene or dinitrotoluene may be isolated under certain process conditions. While such mixtures are not unduly sensitive to impact, friction or thermal initiation, when oxygen-balanced they are extremely sensitive to induced shock and are capable of explosive propagation at film thicknesses below 0.5 mm. It is suspected that many explosions in TNT acid recovery operations, previously attributed to tetranitromethane, may have been caused by such mixtures [2]. 

Matsunaga T., Tamura M., Iwama A. and Yoshida T., "A Study on Evaluating Method of Impact Sensitivity and Explosion Propagation for HMX Added Composite Propellants (First Report) -Evalutaion by Spring Mortar and Spring Pendulum", Industrial Explosives 48, 95 (1987)... 

Standard safety procedures include attention to such matters as intraline distances to minimize explosion propagation, cleanliness, nonsparking equipment and explosion-proof motors, and location in selected areas away from the heavily populated areas. The development of continuous processes for explosive manufacture that use extensive automatic controls and minimize in-line quantities has contributed significantly to decreasing the hazards of operations. 

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