Vapor plume

VDI Part 1 models the dispersion of vapor plumes with output consisting of vapor ctiriccntration as a function of time and downwind distance and denser-than-air vapor releases. VDI Part 2 determines the downwind distance to the lower flammable limit of a combustible vapor. Part 2 may also be used in conjunction with Part 1 to model a toxic gas emission. 

If a combustible gas release is not ignited immediately, a vapor plume will form. This will drift and be dispersed by the ambient winds or natural ventilation. If the gas is ignited at this point, but does not explode, it will result in a flash fire, in which the entire gas cloud bums very rapidly. It is unlikely to cause any fatalities, but will damage steel structures. If the gas release has not be isolated during this time, the flash fire will bum back to a jet fire at the source of the release. A flash fire is represented by its limiting envelope, since no damage is caused beyond it. This envelope is usually taken as the LEL of the gas cloud. 

What role does the dopant play in APPI (Ionization of molecules having a low photoionization cross section (probability) has been shown to be enhanced by the use of a dopant that is introduced into the vaporized plume of analyte molecules the dopant is selected on the basis of its high UV absorptivity and serves as a charge transfer reagent). 

Puretzky, A.A. Geohegan, D.B. Hurst, G.B. Buchanan, M.V. Luk yanchuk, B.S. Imaging of Vapor Plumes Produced by Matrix Assisted Laser Desorption A Plume Sharpening Effect. Phys. Rev. Lett. 1999,83,444-447. 

Figure 7.2 Response of Fido to a vapor plume 2 m downwind of a TNT source.

Editor That seems to correlate with our observation that the molecules tend to adsorb on soil particles and dust, rather than remain in the air as explosive vapor. I take it that you mean that some wind is needed to move these particles in order to make them available above ground level to the animal. So, a pure vapor plume in air is not as rich a source as wind carried dust and soil particles. Is that correct ... 

Chondrules from metal-rich (CH, CB) chondrites formed significantly later than those in other classes (Fig. 9.9), with Pb-Pb measurements giving ages of -4562.7 Ma, 5.5 Myr after CAIs (Krot et al., 2005). These chondrules likely formed by a different mechanism than the chondrules in other classes. One model of their formation suggests they are products of a collision between two asteroid-sized bodies and that they formed by recondensation of a vapor plume generated in the collision. 

Field measurements of concentrations of disparlure in air under woodland plots treated with three different slow release formulations showed that all released pheromone for about one month concentrations decreased about 80 in the first five days and 90-98 over 35 days. Between 75 and 85 of the disparlure remained in the formulations after 35 days even though release had became very slow. Measurements with other formulations containing tetradecenol formate applied to corn showed these were more efficient but not persistent enough to control Heliothis Zea for more than one month. No satisfactory measurements of concentrations in vapor plumes from point sources were possible even though these may be as effective as broadcasts. Further field research is limited by sampling and analysis techniques and the need for better micrometeorological data. 

Environmental Factors These include (1) equipment location, (2) available space, (3) ambient conditions, (4) availability of adequate utilities (i.e., power, water, etc.) and ancillary-system facilities (i.e., waste treatment and disposal, etc.), (5) maximum allowable emission (air pollution codes), (6) aesthetic considerations (i.e., visible steam or water-vapor plume, etc.), (7) contributions of the air-pollution-control system to wastewater and land pollution, and (8) contribution of the air-pollution-control system to plant noise levels. 

In addition to particulate emissions, volatile organic compounds (VOCs) may also be emitted when the slurry contains organic materials with low vapor pressures. The surfactants included in the slurry represent the origin of the VOCs. The vaporized organic materials condense in the tower exhaust air stream into droplets or particles. Paraffin alcohols and amides in the exhaust stream can result in highly visible plume that persists after the condensed water vapor plume has dissipated [4, 21]. Some of the VOCs identified in the organic emissions are hexane, methyl alcohol, 1,1,1-trichloroethane, perchloroethylene, benzene, and toluene [1-4]. 

Melosh H. J. and Sonett C. P. (1986) When worlds collide jetted vapor plumes and the Moon s origin. In Origin of the Moon (eds. W. K. Hartmann, R. J. Phillips, and G. J. Taylor). Lunar and Planetary Institute, Houston, pp. 621-642. 

Atmospheric pressure photoionization (APPI) is a relatively new technique48-51 but the source design is almost identical to that used for APCI except that the corona discharge needle is replaced by a krypton discharge lamp, which irradiates the hot vaporized plume from the heated nebulizer with photons (10 and 10.6 eV). The mechanism of direct photoionization is quite simple. Where the ionization energy of the molecule is less than the energy of the photon, absorption of a photon is followed by ejection of an electron to form the molecular radical ion M+ (Equation (28)). 

Limitations to high-temperature materials chemistry research due to the non-availability of suitable container materials have been overcome by laser induced vaporization mass spectrometry (see e.g. Ref. 587). This technique couples laser heating of refractory materials under vacuum with the mass spectrometric analysis of the vapor plume. Hastie et al. [588] have recently investigated the vaporization of graphite by this technique. The investigations by Ohse s group on the laser induced vaporization of fast breeder oxide and carbide fuels should also be mentioned in this context (see Refs. 589, 590 and references quoted therein). 

Organization for HAZMAT Emergencies Part 1 Hazards Analysis Uses case studies to explain hazard identification, vulnerability analysis, risk assessment toxicity, flammability, and reactivity of chemicals prioritizing hazards and how vapor plumes are affected by weather and chemical composition. 

Exploiting the enhanced reactivity of Ca often requires the use of two tunable dye lasers (Fig. 2), one to excite the metal atoms to the metastable 3F1 state and the second to detect the product molecules. (Excited metal atoms can also be produced in an electrical discharge or in a laser-vaporized plume.) The two laser beams are introduced into the Broida oven chamber... 

Subsequent programs to prevent water and air pollution supported by Imperial Chemicals Industries Ltd., British Power Authority consultants, and Howden Construction Co. led to the development of a closed-loop, lime-based, sulfur dioxide removal system. These types of systems were installed in 1935 at the Swainsea and in 1937 at the Fulham power plants. They operated successfully until World War II when they were shutdown because the vapor plumes provided aerial guidance to the Luftwaffe. 

The parameters which control the dispersion of mercury vapor plumes still require definition. No plume from an industrial source was tracked... 

The use of high-sensitivity, portable, rapid-response gas-analyzing equipment has led to the detection of several previously unknown elemental mercury plumes associated with both natural and industrial sources. In Northern California these anomalies were detected in a brief reconnaissance program and hence represent only a sampling of the mercury vapor plumes likely to exist in the area. An inventory of elemental mercury plumes can be obtained in any area by using a high-sensitivity, portable, rapid-response mercury detector mounted in a mobile laboratory for measurement while in motion. 

Aesthetic considerations (e.g., visible steam, water vapor plume)... 

FIGURE 18 V ter vapor imagery at the same time as the visible shown in Fig. 17. Note that the tongue of moisture (or the water vapor plume) extended northeastward over North Carolina. The hurricane track appears to follow this vapor plume. Note also that the vapor front which was located west of the vapor plume acts as a blocker to prohibit possible landfall of Floyd over Florida, Georgia, and South Carolina. 

Some of the chemicals and placard ID numbers listed in the guidebook are highlighted in color. For the highlighted chemicals, the user is directed to another section listing initial isolation and protective action distances in miles and kilometers (or feet and meters). The initial isolation distance is defined by a circle, fhe center of which is at the spill site. The protective action distance is defined by a square fhaf has fhe cenfer of one end locafed af fhe spill site and the other side downwind. The square assumes that random changes in wind direction confine the vapor plume to an area within 30° on either side of the predominant wind direction, resulting in a crosswind protective action distance equal to the downwind protective action distance. This is shown in Fig. 17.1. 

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