Explosion Potentials

OSHA and ACGIH have not estabhshed specific airborne exposure limits for PVB and PVF resias however, some products may contain sufficient fines to be considered nuisance dust and present dust explosion potential if sufficient quantities are dispersed ia air. Unformulated PVB and PVF resias have flash poiats above 370°C. The lower explosive limit (lei) for PVB dust ia air is about 20 g/m. ... 

Cellulose esters, like most dry organic materials in powder form, are capable of creating dust explosions (133). The explosion at Bayer s cellulose acetate plant at Dormagen, Germany in 1976 can attest to the explosive potential of dust. Damage to the plant was estimated at between DM 5—10 million (134). 

The kinetics and thermodynamics of the reaction, and of possible side reactions, need to be understood. The explosive potential of chemicals liable to exothermic reaction should be carefully appraised. 

The ineident eommander may rely on visual observation of plae-ards, labels, and manifests and information gathered during the response. Obtaining air measurements with monitoring equipment for toxie eon-eentrations of vapors, partieulates, explosive potential, and the possibility of radiation exposure is important for determining the nature, degree, and extent of the hazards [2]. 

An appreciation of the explosive potential of ammonium nitrate. Shipping it from Texas City is forbidden. 

Two of the previously mentioned accidents and the Oklahoma City bombing showed the explosive potential of nitrogen fertilizer so this is a good place to stan. 

A liquid not considered flammable may still have an explosive potential. An example is dichloromethane or methylene chloride, often used in paint strippers, which evaporates very quickly. It is not flammable, but its vapors may be explosive (explosive limits 12% to 22%). 

If, on the other hand, a vapor cloud s explosive potential is the starting point for, say, advanced design of blast-resistant structures, TNT blast may be a less than satisfactory model. In such cases, the blast wave s shape and positive-phase duration must be considered important parameters, so the use of a more realistic blast model may be required. A fuel-air charge blast model developed through the multienergy concept, as suggested by Van den Berg (1985), results in a more realistic representation of a vapor cloud explosion blast. 

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 two approaches lead to completely different procedures for vapor cloud explosion hazard assessment. If conventional TNT-equivalency methods are applied, explosive potential is primarily determined by the amount of fuel present in a cloud, whether or not within flammability limits. The cloud center is the potential blast center and is determined by cloud drift. 

TNT-equi valency methods express explosive potential of a vapor cloud in terms of a charge of TNT. TNT-blast characteristics are well known fiom empirical data both in the form of blast parameters (side-on peak overpressure and positive-phase duration) and of corresponding damage potential. Because the value of TNT-equiva-lency used for blast modeling is directly related to damage patterns observed in major vapor cloud explosion incidents, the TNT-blast model is attractive if overall damage potential of a vapor cloud is the only concern. 

Quantify the explosive potential of a vapor cloud which results firom the postulated propane release, and calculate the potential blast effects. Because it is dense, the flammable propane-air cloud spreads in a thin layer and covers a substantial area, including the tank farm and paiking lot. An overview of the tank farm site is given by the map in Figure 7.3b. 

The multienergy method applies only if detonation of unconfined parts of a vapor cloud can be ruled out. If so, the explosive potential of a vapor cloud is determined primarily by the blast-generative properties of the environment in which the vapor is released and disperses. Consequently, a vapor cloud explosion can be regarded as a number of subexplosions. Therefore, the first step in applying the multienergy method in vapor cloud explosion hazard assessment is... 

TABLE 7.2. Side-On Peak Overpressure for Several Distances from Charge Expressing Explosive Potential of a Vapor Cloud at a Storage Site for Liquefied Hydrocarbons... 

Common reaction rate v. temperature characteristics for reactions are illustrated in Figure 6.5. To avoid runaway conditions (Fig. 6.5a) or an explosion (Figure 6.5c), it may be essential to control the rate of addition of reactants and the temperature. The kinetics and thermodynamics of the reaction, and of possible side reactions, need to be understood. The explosive potential of chemicals liable to exothermic reaction should be carefully appraised. 

The company standards classify this facility as "high explosion potential," requiring control buildings that are located at this distance [125 ft (38 m)] from a potential explosion be designed to a minimum load of 10 psi (0.69 bar) side-on overpressure and 20 ms blast load. It was determined that this... 

Site-specific consequence screening for explosion can be performed either qualitatively or quantitatively, depending upon the explosion potential of the materials being handled, as well as processing conditions and other site-specific factors. In performing a consequence screening, it is necessary to select "Evaluation-case" events for consideration. This is defined as follows ... 

In a qualitative evaluation, the inherent properties of the materials are assessed for explosion potential, in combination with a review of site conditions. An assessment is then made as to the potential for explosion, based on the experience level and judgment of the assessor. 

For vapor to move in the unsaturated zone, the soil formations must be sufficiently dry to permit the interconnection of air passages among the soil pores. Vapor concentration and vapor flow govern its movement. Vapor can move by diffusion from areas of higher concentration to areas of lower concentration and ultimately to the atmosphere. Therefore, the transportation of the vapor phase of gasoline components in the unsaturated zone can pose a significant health and safety threat because of inhalation and explosion potential. 

Methyl trifluorovinyl ether, b.p. 10.5- 12.5°C, prepared from tetrafluoroethylene and sodium methoxide [1], has considerable explosive potential. On ignition, it decomposes more violently than acetylene and should be treated with extreme caution [2], Other trifluorovinyl ethers are similarly available from higher alkoxides [1], and although not tested for instability, should be handled carefully. Presence of fluoro-haloalkanes boiling lower than the ether stabilises the latter against spark-initiated decomposition in both fluid phases [3],... 

In a study of explosive potential of 20 pharmaceutical products, Chloramine B was found to present the greatest fire hazard, decomposing explosively at 185°C. 

Energy of explosion. The energy of explosion values given in Table 16.2 should be considered as the theoretical maxima, and yield factors of 10% are considered reasonable for fuel-air explosions. For equivalent volume storage, hydrogen has the least theoretical explosive potential of the three fuels considered, albeit it has the highest heat of combustion and explosive potential on a mass basis. 

This chapter will discuss the evaluation of dust explosion potential at various manufacturing operations in three Army Ammunition Plants. The assessment of data from each plant will be presented in detail. 

In each of these plants, the characterization of the dust explosion potential was carried out by sampling transport ducts for explosive dust concentrations during an actual plant operation. The critical measurements taken were the quantification of explosive dust concentrations and level of electric energy generated from the electrostatic charge accumulations found in the duct. 

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