Overpressure detonations

In the overpressure detonation, Rayleigh line represents the line of momentum and mass conservations Hugoniot curve represents the curves of energy conservation. 

If a large amount of a volatile flammable material is rapidly dispersed to the atmo vapor cloud forms. If this cloud is ignited before the cloud is diluted below its lower flammability limit, a UVCE occurs which can damage by overpressure or by thermal radiation. Rarely are UVCEs detonations it is believed that obstacles, turbulence, and possibly a critical cloud size are needed to transition from deflagration to detonation. 

Detonation flame arresters and associated piping mnst be able to withstand the effects of explosion transients that inclnde the pressnre or pres-snre-related force, the specific impulse (integral of the dme versus overpressure) or net impulse (upstream minns downstream impulse) highspeed gas momentnm transfer and flnx, and temperatnre-, heat-, and dier-mal-flnx related loads (White and Oswald 1992). Wliite and Oswald con-... 

There are no clearly discernable, broadly applicable, correlations between the 6-inch and 1 S-inch deflagration and detonation experiments. Therefore, comparisons were done on a parameter-byparameter basis. However, comparisons of data taken during experiments with the two pipe sizes reveal that enough scale-related differences exist that interpolation between the two scales for an intermediate size should be done only where conditions are very similar. Then, overpressure and specific impulse can be estimated based on L/D. 

For describing structural loading functions needed for design analysis, the use of overdriven detonation data representing the net overpressure (run-up side less protected side overpressure) on the arrester element and supporting structure is preferable to data representing only the run-up side, side-on overpressure. However, the run-up side transient history of side-on overpressure for overdriven detonations should provide a conservative estimate for design purposes (see Chapter 6). 

Galloping Detonation A detonation that periodically fails and reinitiates during propagation. This type of detonation is typically observed in near-limit mixtures. Since it reinitiates via DDT, a galloping detonation is periodically overdriven and results in large overpressures at periodic distances along a pipe. 

The investigators found that overpressures from the evaporating liquid compared well with those resulting from gaseous detonations of the same energy. 

Calculate the total burning time of tlie octane pool in Illustrative Exatiiple 3. Calculate tlie peak overpressure of a 50-pound TNT explosion at a distance 200 feet from the ignition point, if tlie peak oi erpressure at 1000 feel is 0.10 psi when 150 pounds of TNT is detonated. 

Unlike reactions such as certain oxidations and polymerizations, hydroge nations will noi detonate unless the substrate or solvent itself is explosive or undergoes extensive decomposition. Excessive pressures can only come from overpressuring the reaction vessels and from pressures generated by large... 

At times it is necessary to have a feel for overpressure as it relates to shock front velocity [49]. (See Figure 7-60). Note especially that for a reasonable detonation velocity the peak overpressure could be in the range of 700 to 1000 psi and when referenced to Figure 7-60, the extent of industrial damage would be catastrophic. The use of scaled distance is illustrated in Ref. [41]. 

Rupture disks when properly sized and located on the potentially overpressure vessel have been shown to provide the best protection for a deflagration but not a detonation [54],... 

Explosion calculations, 499-504 Estimating destruction, 501 Overpressure, 502 Pressure piling, 501, 504 Relief sizing, 505 Scaled distance, 502, 503 Schock from velocity, 503 TNT equivalent, 499-504 Explosion characteristics of dusts, 515 Explosion suppression, 518 Explosion venting, gases/vapors, 504 Bleves, 504 Explosions, 482 Blast pressure. 496 Combustion, 482 Confined, 482 Damage, 498-501 Deflagration, 482 Detonation, 483... 

Nomenclature Peak Overpressure, PSI Impulse, PSI-Msec Detonation Elate, M/Sec Qe, cal/g (H20 Liq at 25°) Refs... 

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