Deflagration detonation

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... 

Flame transmission test procedures for deflagration, detonation, and bnrning tests are discussed in all of the above sections. 

The primary concern abont hazardons processes is that they be operated in a safe manner so that fires, deflagrations, detonations, and releases of flammable and toxic gases into the atmosphere or inside process bnildings are eliminated or minimized. Also of great concern from an environmental standpoint is the control and minimization of volatile organic componnd (VOC) emissions from process vents and fugitive sources. 

It also contains specific requirements for testing of flame arresters in equipment such as compressors, blowers, fans, and vacuum pumps. Procedures are presented for deflagration, detonation, and burning tests for all the flame arrester types in the standard. 

This volume consists of two parts Chapters 1-6 and Chapters 7-9. Chapters 1 through 6 offer detailed background information. They describe pertinent phenomena, give an overview of past experimental and theoretical research, and provide methods for estimating consequences. Chapter 2 describes the phenomena covered, identifies various accident scenarios leading to each of the events, and describes actual accidents. In Chapter 3, principles such as dispersion, deflagration, detonation, blast, and radiation are explained. 

This chapter describes the main features of vapor cloud explosions, flash fires, and BLEVEs. It identifies the similarities and differences among them. Effects described are supported by several case histories. Chapter 3 will present details of dispersion, deflagration, detonation, ignition, blast, and radiation. 

A deflagration-detonation transition was first observed in 1985 in a large-scale experiment with an acetylene-air mixture (Moen et al. 1985). More recent investigations (McKay et al. 1988 and Moen et al. 1989) showing that initiation of detonation in a fuel-air mixture by a burning, turbulent, gas jet is possible, provided the jet is large enough. Early indications are that the diameter of the jet must exceed five times the critical tube diameter, that is approximately 65 times the cell size. 

Schildknecht, M. 1984. Versuche zur Freistrahlzondung von Wasserstoff-Luft-Gemischen im Hinblick auf den Ubergang Deflagration-Detonation, report BIeV-R-65.769-1, Battelle Institut e.V., Frankfurt, West Germany. 

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]. 

Whether mixtures of the perchlorate with aluminium truly detonate is under debate. However, appropriate compositions certainly explode violently even when uncontained, so the deflagration/detonation dispute is essentially academic [1]. Presence of aluminium fluoride increases the ease of ignition of aluminium-perchlorate mixtures, owing to complex fluoride formation [2],... 

Most VCEs involving flammable liquids or gases result only in a deflagration—detonations are unlikely. As the confinement of the vapor cloud increases, due to congestion from process equipment, the flame accelerates and higher overpressures are achieved. The higher overpressures may approach the severity of a detonation. 

Pyrolants deflagration detonation gas generators, igniters, fireworks, squibs, safety fuses detonators, primers, initiators, detonating fuses... 

Detonation by W.H. Rinkenbach) and 369-72 (Explosives, Pre-explosion reactions, Explosive deflagration, Detonation and Explosion... 

Ignition of a fuel-oxidizer mixture occurs when an external source of energy initiates interactions among the controlling convective, transport and chemical processes. Whether the process results in deflagration, detonation, or is simply quenched depends on the intensity, duration, and volume affected by an external heat source. Ignition also will depend on the initial ambient properties of the mixture which determine the chemical induction... 

In dust explosions the combustion process is very rapid. The flame speed is high compared with that in gas deflagrations. Detonations normally do not occur in dust explosions in industrial plants. 

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