Point-source explosives

In the earliest applications of numerical methods for the computation of blast waves, the burst of a pressurized sphere was computed. As the sphere s diameter is reduced and its initial pressure increased, the problem more closely approaches a point-source explosion problem. Brode (1955,1959) used the Lagrangean artificial-viscosity approach, which was the state of the art of that time. He analyzed blasts produced by both aforementioned sources. The decaying blast wave was simulated, and blast wave properties were registered as a function of distance. The code reproduced experimentally observed phenomena, such as overexpansion, subsequent recompression, and the formation of a secondary wave. It was found that the shape of the blast wave at some distance was independent of source properties. 

It was fortunate that, for the BURRO-9 test, RPTs were anticipated and a pressure transducer was located in the air about 30 m from the LNG injection point. The reflected overpressures at various times are shown in Table Vin. Also given on the same table are the TNT equivalents assuming a free-air, point-source explosion. Some equivalents were significantly higher than noted in the smaller Shell Pipeline tests. 

Point Source Explosion in Air , The Rand Corporation, Research Memorandum RM-1824(1956) 15) V.P. Korobeinikov,... 

Cook (1958), 99-106 (Detonation wave front) 20) Baum, Stanyukovich Shekhter (1959),598-624 (Teoriya tochecbnago vzryva) (Theory of point source explosion) 624-40 (Sfericheskii vzryv) (Spherical explosion)... 

The calculated equivalent amount of TNT energy can now be used to estimate shock wave effects. The analogy of the explosion of a container of pressurized gas to a condensed phase point source explosion of TNT is not appropriate in the near field since the vessel is not a point source. Prugh (1988) suggests a correction method using a virtual distance from an explosion center based on work by Baker et al. (1983) and Petes (1971). This method is described below. 

Part 457 explosives manufacturing point source category Part 458 carbon black manufacturing point source category... 

The factors tliat affect miconfined I apor cloud explosions me not well understood. In a model developed by William, it is assmned tliat ignition occurs at a point source, tliat tlie flame front travels out from tlie core at a flame speed S, and tliat the pressure waves produced by the flame generate a weak shock wave tliat travels ahead of tlie flame with a time-dependent velocity. Tlie equation for the flame speed for spherical systems is... 

The TNT equivalency method also uses an overpressure curve that applies to point source detonations of TNT. Vapor cloud explosions (VCEs) are explosions that occur because of the release of flammable vapor over a large volume and are most commonly deflagrations. In addition, the method is unable to consider the effects of flame speed acceleration resulting from confinement. As a result, the overpressure curve for TNT tends to overpredict the overpressure near the VCE and to underpredict at distances away from the VCE. 

Liquids under pressure (pipeline leaks, pump seal failures, etc.), will be thrown some distance from the point source, while atmospheric leakages will emit at the point of release. The other characteristic of liquid releases is their flash points. High flash point liquids, not operating above their flash point temperatures, are inherently safer than low flash point liquids. Most liquid fires are relatively easy to contain and suppress while gas fires are prone to explosion possibilities if extinguished and source points are not isolated. 

In general, detonation of an explosive is initiated by a primer as a point-source. The detonation wave formed at the point-source propagates into the explosive in a spherical manner as shown in Fig. 9.1. 

In initiation from a point source and subsequent expansion of a spherical detonation front , the quantity of explosive absorbing the energy at any time exceeds that in a layer of the same original thickness releasing the energy. In effect, the energy per unit mass available for propagating the wave is decreased by convexity of the wave front. 

Point Source. See under DETONATION (EXPLOSION AND COMBUSTION), SPHERICAL... 

Increasing the mass at the same time as mixing the radioactive sources throughout the star will both keep the peak in the light curve near the observed 90 day point after explosion, and broaden the curve. Both of the features would improve the fit in Ref. 12 to the observed light curve. 

When a patient presents to the ED, the nurse must ascertain that an exposure has taken place. Nurses should suspect chemical exposures for any mass casualty incident in which multiple ill persons with similar clinical complaints (point-source exposure) seek treatment at about the same time or in persons who are exposed to common ventilation systems or unusual patterns of death or illness. The ED may or may not receive notification in advance that a chemical explosion or leak has occurred. In either case, ED health care providers have the following three primary goals in treating a patient who has been exposed to a hazardous material and may be contaminated or who has not undergone adequate decontamination before arrival at the hospital ... 

The discrimination between explosion and earthquake is generally based on the shape difference between the observed seismic signals. The seismic sources associated with explosions and with earthquakes have very different characteristics. The explosions are point sources in space (a few hundred metres) and in time (a few tenths of a second), whereas earthquakes result from shifting of faults which can be as long as several tens of kilometres. The explosions are essentially superficial (depths of less... 

EPA. 1976. Explosives manufacturing point source category. U.S. Environmental Protection Agency. Code of Federal Regulations. 40 CFR 457.11. 

All laboratory personnel should know the properties of chemicals they are handling as well as have a basic understanding of how these properties might be affected by the variety of conditions found in the laboratory. As stated in section 5.B, Laboratory Chemical Safety Summaries (LCSSs) or other sources of information should be consulted for further information such as vapor pressure, flash point, and explosive limit in air. The use of flammable substances is common, and their properties are also discussed in Chapter 3, section 3.D. 

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