Deflagrations and explosions

Deflagration and explosion, including dust explosibility and ignitability Table A.2 Theoretical Hazard Rankings... 

In many cases it is difficult to distinguish between deflagration and explosion Refs Same as listed after "Heat of. Explosion and Heat of Detonation"... 

Sheffield, PATR 2700, Vol 3(1966), pp C447 to C449 (Thermochemical calculations for coal mining expls, which include heats of combustion, deflagration and explosion of such expls) 49a) Chemical Rubber Publishing Co, "Handbook of Chemistry and Physics , Cleveland, Ohio(1968-69)... 

Experiments on burning nitrocellulose (deflagration and explosion) were carried out in World War II by Rideal and A. J. B. Robertson [91]. One interesting observation they made was that nitrocotton heated for a long time at 200°C under a pressure of 50 mm Hg liquefied shortly before the explosion. Nitrocellulose has been known to melt while being stabilized in an autoclave at an elevated temperature, since it overheats if there is too little water in the autoclave (on melting nitrocellulose, see p. 242). 

Orange-red, monoclinic needles from benzene, mp 178. Additional purification by sublimation in high vacuum, (bath temp 100"). mp 180. bp ca. 185°, Further heating results in deflagration and explosion. Practically insol in cold water, hydrolyzed by boiling water. Slightly sol in benzene, abs ethanol, carbon disulfide. Handle with caution May dec explosively on striking or at temps much above 100. ... 

The pressure developed by decomposition of acetylene in a closed container depends not only on the initial pressure (or more precisely, density), but also on whether the flame propagates as a deflagration or a detonation, and on the length of the container. For acetylene at room temperature and pressure, the calculated explosion pressure ratio, / initial > deflagration and ca 20 for detonation (at the Chapman-Jouguet plane). At 800 kPa (7.93... 

Chemical explosives detonate, or deflagrate. Detonating explosives (e.g., TNT or dynamite) rapidly decompose to produce high pressure and a shock front (travels faster than the velocity of sound). Deflagrating explosives (e.g., black and smokeless powders) bum fast, prodr er... 

Thibault, P., Britton, L. G., and Zhang, F. 2000. Deflagration and Detonation of Ethylene Oxide Vapors m Pipelines. Process Safety Progress, 19(3), 125-139. an Dolah, R. W. and Burgess, D. S. 1974. Explosion Problems in the Chemical Industry. 

Whereas Fishbum was mainly interested in the detonative mode of explosion, Luckritz (1977) and Strehlow et al. (1979) focused on the simulation of generation and decay of blast from deflagrative gas explosions. For this purpose, they employed a similar code provided with a comparable heat-addition routine. Strehlow et al. (1979), however, realized that perfect-gas behavior, which is the basis in the numerical scheme for the solution of the gas-dynamic conservation equations, is an idealization which does not reflect realistic behavior in the large temperature range considered. 

Experimental data (Section 4.1) may be used to estimate a blast s initial strength. These data indicate that deflagrative gas explosions may develop overpressures ranging from a few millibars under completely unconfined or unobstructed conditions to greater than 10 bars under severely confined and obstructed conditions. 

The three basic types of explosions to be concerned about in the chemical and petrochemical environment are combustion explosions (deflagrations), detonation explosions, and BLE 7Es or boiling-liquid expanding vapor explosions [38]. 

A special study [74] was commissioned by the American Petroleum Institute (API) entitled Mitigation of Explosion Hazards of Marine Vapor Control Systems. The report examines the effects of deflagrations and detonations in pipes in the region of detonation flame arrestors. The primary objective was to resolve potential... 

VasU ev (Ref 36) impacted various explosives with steel plates and followed events with a framing camera. PA at 1,59g/cc impacted with a 3-mm thick steel plate at 430m/sec showed only deflagration and no expins. Initially the burning rate was low but reached 600m/sec in about 65 microseconds after impact C. Potential Hazards. The main danger of accidental expln of PA appears to be in fires. There appears to be uncertainty if explns result if PA bums out of contact with metals. On p 494, Urbanski (Ref 35) states ... 

Silver acetylide decomposition was studied [679] by X-ray diffraction and microscopic measurements and, although the a—time relationship was not established, comparisons of intensities of diffraction lines enabled the value of E to be estimated (170 kj mole 1). The rate-limiting step is believed to involve electron transfer and explosive properties of this compound are attributed to accumulation of solid products which catalyze the decomposition (rather than to thermal deflagration). 

Above 400°C in hydrogen, deflagration and flaming of the polymer occurs, the vigour depending on the fluorine content. Rapid heating to 500°C in an inert atmosphere causes explosive deflagration. 

In pipe systems explosions can initiate as deflagrations and the flame front may accelerate to detonation speeds. 

Basics of Free-Field Blast Waves. The most severe types of energy releases which can occur in toxic chemical and explosives facilities are explosions of high explosive materials. When such materials are initiated by some stimulus, they may burn, deflagrate or detonate. Detonation is by far the most severe of these three chemical reactions, so it is usually assumed to occur in accident situations, unless one can prove otherwise quite conclusively. 

A physical explosion, for example, a boiler explosion, a pressure vessel failure, or a BLEVE (Boiling Liquid Expanding Vapor Explosion), is not necessarily caused by a chemical reaction. Chemical explosions are characterized as detonations, deflagrations, and thermal explosions. In the case of a detonation or deflagration (e.g., explosive burning), a reaction front is present that proceeds through the material. A detonation proceeds by a shock wave with a velocity exceeding the speed of sound in the unreacted material. A... 

With pressure-time data from spontaneous deflagrations (thermal explosions), the maximum expected pressure, and the time for pressure-rise can be estimated. Furthermore, the so-called "specific energy" (F) or "explosive power" of substances [24, 31] by Equation (2-22) from experiments in which the sample mass is varied. 

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