Combustion explosion

Theatrical Pyrotechnics or Special Effects. Many spectacular visual and audible effects are produced for stage presentations of both music and drama, and many motion pictures and television shows incorporate pyrotechnic and explosive special effects to Hven up the presentation. These spectacular effects are a combination of pyrotechnics, explosives, combustion, and electronics. After the effects are filmed or videotaped, they are often enhanced by slow-motion replay and by the addition of more exciting noise. A real explosion is over in milliseconds, and hence there is a need for electronic enhancement to create a more spectacular effect on the screen. 

Combustible gas detection systems are frequently used in areas of poor ventilation. By the early detection of combustible gas releases before ignitible concentration levels occur, corrective procedures such as shutting down equipment, deactivating electrical circuits and activating ventilation fans can be implemented prior to fire or explosion. Combustible gas detectors are also used to substantiate adequate ventilation. Most combustible gas detection systems, although responsive to a wide range of combustible gases and vapors, are normally calibrated specifically to indicate concentrations of methane since most natural gas is comprised primarily of methane. 

Figure 2.1 identifies the conditions necessary for the occurrence of a flash fire. Only combustion rate differentiates flash fires from vapor cloud explosions. Combustion rate determines whether blast effects will be present (as in vapor cloud explosions) or not (as in flash fires). 

Furthermore, accidental vapor cloud explosions are anything but detonations of the full amount of available fuel. Therefore, practical values for TNT equivalencies of vapor cloud explosions are much lower than the theoretical upper limit. Reported values for TNT equivalency, deduced from the damage observed in many vapor cloud explosion incidents, range from a fraction of one percent up to some tens of percent (Gugan 1978 and Pritchard 1989). For most major vapor cloud explosion incidents, however, TNT equivalencies have been deduced to range from 1% to 10%, based on the heat of combustion of the full quantity of fuel released. Apparently, only a small part of the total available combustion energy is generally involved in actual explosive combustion. 

On the other hand, turbulence may also be generated by external sources. For example, fuels are often stored in vessels under pressure. In the event of a total vessel failure, the liquid will flash to vapor, expanding rapidly and producing fast, turbulent mixing. Should a small leak occur, fuel will be released as a high-velocity, turbulent jet in which the fuel is rapidly mixed with air. If such an intensely turbulent fuel-air mixture is ignited, explosive combustion and blast can result. 

Pickles, J. H., and S. H. Bittleston. 1983. Unconfined vapor cloud explosions—The asymmetrical blast from an elongated explosion. Combustion and Flame. 51 45-53. 

The consequence of the second approach is that, if detonation of unconfined parts of a vapor cloud can be ruled out, the cloud s explosive potential is not primarily determined by the fuel-air mixture in itself, but instead by the nature of the fuel-release environment. The multienergy model is based on the concept that explosive combustion can develop only in an intensely turbulent mixture or in obstructed and/or partially confined areas of the cloud. Hence, a vapor cloud explosion is modeled as a number of subexplosions corresponding to the number of areas within the cloud which bum under intensely turbulent conditions. 

The jet by which the propane is released. The jet s propane-air mixture is in intensely turbulent motion and will develop an explosive combustion rate and blast effects on ignition. 

In the rest of the cloud, which is unconfined and unobstructed, no explosive combustion rates can be maintained nor developed. 

Equipment shall be approved not only for the class of location but also for the explosive, combustible, or ignitable properties of the specific gas, vapor, dust, fiber, or flyings that will be present. In addition. Class I equipment shall not have any exposed surface that operates at a temperature in excess of the ignition temperature of the specific gas or vapor. Class II equipment shall not have an external temperature higher than that specified in Section 500-3(1). Class III equipment shall not exceed the maximum surface temperatures specified in Section 503-1. 

Uses. (See also under Perchlorate Explosives) Combustible Cartridge Cases. Cotton cloth is impregnated with a siurry of AP and a monomer in methyl ethyl ketone, the solv evapd, and the monomer cured on a meld to give a combustible cartridge case (Ref 35)... 

The time period before fuel ignition and after boiler shutdown when explosive combustibles are removed from the furnace area by air purging. 

Starke, R. and Roth, P, An experimental investigation of flame behavior during cylindrical vessel explosions. Combustion and Flame, 66,249-259,1986. 

Moen, 1.0. et al.. Pressure development due to turbulent flame propagation in large-scale methane-air explosions. Combust. Flame, 47,31, 1982. 

Barium sulphide has the usual dangerous reactions of sulphides (detonations with potassium chlorate and nitrate, combustion with phosphorus pentoxide). It catalyses the explosive combustion of dichlorine oxide. 

Aniline reacts with perchloric acid and then formaldehyde to give an explosively combustible condensed resin. 

The potential for explosive combustion of mixture of sodium chlorate-based herbicides with other combustible agricultural materials was determined. Initiation temperatures and maximum combustion temperatures were measured for mixtures of sodium (or potassium) chlorate with peat, powdered sulfur, sawdust, urotropine (hexamethylenetetramine), thiuram and other formulated materials. With many combinations, maximum temperature increases of 500-1000°C at rates of 400-12007s were recorded for 2 g samples. 

A safe method for demonstrating explosive combustion of acetylene-oxygen mixtures in bubbles is described. 

Diethyl ether is a very low-boiling, highly flammable liquid => open flames or sparks from light switches can cause explosive combustion of mixture of diethyl ether and air. 

D. L. Ornellas, The Heat and Products of Detonation in a Calorimeter of CNO, HNO, CHNR CHNO, CHNOF, and CHNOSi Explosives, Combustion and Flame 23, 37-46 (1974). 

Dust Explosions Combustible Particles and Control, PB84-878073, Richmond (Va.), USNTIS, 1984... 

Kuhl, A. L., R. E. Ferguson, K. Y. Chien, J. P. Collins, and A. K. Oppenheim. 1995. Gasdynamic model of turbulent combustion in an explosion. Combustion, Detonation, Shock Waves. Zel davich Memorial Proceedings. Eds. A. G. Merzhanov and... 

The light metals sodium, magnesium and aluminium are adjacent on the periodic table and have a common origin. They are found in profusion in the ashes from gentle, non-explosive combustion of carbon and neon. Production of sodium and aluminium grows as the Galaxy evolves. 

Before the submerged combustion melter can operate successfully, stable combustion of the fuel within the melt must be achieved. The injection of a combustible mixture into a melt results in the formation of cold channels, leading to explosive combustion and excessive melt fluidization. 

It is well known that reactions take place at different rates. Some reactions occur in an instant, while others can be measured in seconds, minutes, and hours. The explosive combustion of gasoline in the cylinder of a car occurs in a fraction of a second. Reactions used to develop film take place over seconds to minutes. Chemical reactions responsible for changing the color of fall leaves take days to weeks, and the oxidation of metals takes place over years. Whenever reactions occur, chemical kinetics play a... 

Ballistic Process of Conversion of an Explosive or Propellant See under Detcnative (or Explosive) Combustion... 

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