Cloud diameter

Illustrative Values of Maximum Permissible Cloud Diameter for Various Particle Concentrations (for < , = 1 V/micron pp = 1 gm/cm3 Dp = 10 microns)... 

Three-dimensional detector coverage, as shown in Figure 8-5, can be obtained by a triangular grid (isometric) pattern of point or open path detectors, with a maximum separation less than the gas cloud diameter that can... 

Sedgewick Pierce (Ref 26a) are developing a one-kiloton FAE simulator. They envision the formation of point-source initiated hemispherical FAE clouds by multiple nozzle fuel injection. They estimate that with propylene oxide fuel the minimum cloud diameter should be 142m... 

K. Cloud diameter, D2 The diameter of the cloud may be easily obtained by rearranging Eqn. (10) to give... 

Any atom has a tiny nucleus, diameter m, in the center ofa relatively enormous electron cloud, diameter m. The negative charge of the electron cloud exactly... 

In Eq. (10.142) D denotes the cloud diameter in m and S the flame speed according to Eq. (10.138). Cloud size and its part within the explosion limits can be determined from dispersion calculations. 

The first small trap designed for storing reduced numbers of laser-cooled ions was created in Heidelberg in 1978 [33]. This trap, which stores some 10 to 20 ions, was made up of a torus of semi-circular cross-section of 0.32 cm internal diameter and two hemispherical caps. An RF drive frequency of 2.6 MHz at 200 Vp p results in a well depth of 10 eV and an axial secular frequency of 370 kHz for the Ba ion. Before laser cooling, the ion cloud diameter was ca 250 pm in the presence of viscous drag cooling. 

Example 3-5 A cloud of coal particles is traveling through a system. The cloud diameter is estimated to be 0.0254 m and the individual particles are 60 pm in diameter with a density of 1200 kg/m. The total cloud is moving such that its drag coefficient is constant at 0.44. The individual particles in the cloud move much slower, such that the drag coefficient is given by Stokes law. The system has atmospheric air transporting the solids, and the cloud density is 160 kg/m. Determine the ratio of internal velocity to cloud particle velocity. 

FIG. 17-14 Biihhling-hed model of Kunii and Levenspiel. dy = effective hiih-ble diameter, = concentration of A in hiihhle, = concentration of A in cloud, = concentration of A in emulsion, y = volumetric gas flow into or out of hiihhle, ky,- = mass-transfer coefficient between bubble and cloud, and k,. = mass-transfer coefficient between cloud and emulsion. (From Kunii and Leoen-spiel, Fluidization Engineering, Wiley, New York, 1.96.9, and Ktieger, Malahar, Fla., 1977.)... 

A material that has a high toxicity does not necessarily present a severe toxic hazard. For example, a ton of lead arsenate spilled in a busy street is unhkely to poison members of the public just a short distance from the spiU, because it is not mobile. It could be carefully recovered and removed and would present a low risk to the gener pubhc, even though it is extremely toxic. On the other hand, a ton of liquefied chlorine spilled on the same street could become about 11,000 fF of pure gas. The IDLH for chlorine is 25 ppm. This is a concentration such that immediate action is required. Thus, the one ton of chlorine, if mixed uniformly with air, could create a cloud of considerable concern, having a volume of about 4.4 X 10 fF or a sphere 770 ft in diameter. This could quickly spread over downwind areas and... 

Volume of vessel (free volume V) Shape of vessel (area and aspect ratio) Type of dust cloud distribution (ISO method/pneumatic-loading method) Dust explosihility characteristics Maximum explosion overpressure P ax Maximum explosion constant K ax Minimum ignition temperature MIT Type of explosion suppressant and its suppression efficiency Type of HRD suppressors number and free volume of HRD suppressors and the outlet diameter and valve opening time Suppressant charge and propelling agent pressure Fittings elbow and/or stub pipe and type of nozzle Type of explosion detector(s) dynamic or threshold pressure, UV or IR radiation, effective system activation overpressure Hardware deployment location of HRD suppressor(s) on vessel... 

What is the approximate lowering of the centroid of a dispersing cloud of particles at 2 km from the source whose mass medium diameter is 30 ptm and whose particle density is 1 g cm in a 5 m s wind ... 

Cloud point. Measures the solubility/compatibility of a resin with solvents. The value reported is the temperature at which a specific mixture of a resin and a solvent or solvents blend gives a cloudy appearance, having been cooled from a temperature at which the mixture was clear. Commonly, a test tube of a given diameter is used and the temperature is noted when the lower end of the thermometer, placed at the bottom of the tube, disappears. Resins with cloud points below 0°C are commonly regarded as soluble and cloud points greater than 10°C indicate poor solubility/compatibility. White spirit with various aromatic contents is a widely used solvent in the determination of cloud point, but other solvents or solvents mixtures are also used. 

The flow pattern of gas within the emulsion phase surrounding a bubble depends on whether the bubble velocity Ug is less than or greater than minimum fluidization velocity U . For Ubflow lines. For Ub> U , the much different case of Figure 4(B) results. Here a gas element which leaves the bubble eap rises much more slowly than the bubble, and as the bubble passes, it remms to the base of the bubble. Thus, a cloud of captive gas surrounds a bubble as it rises. The ratio of eloud diameter to bubble diameter may be written... 

When the reboiler was brought back on line, the water was swept into the heat transfer oil lines and immediately vaporized. This set up a liquid hammer, which burst the surge tank. It was estimated that this required a gauge pressure of 450 psi (30 bar). The top of the vessel was blown off in one piece, and the rest of the vessel was split into 20 pieces. The hot oil formed a cloud of fine mist, which ignited immediately, forming a fireball 35 m in diameter. (Mists can explode at temperatures below the flash point of the bulk liquid see Section 19.5.)... 

The flash fire that resulted was described as a ball of flame with a diameter of at least 120 m (400 ft). No concussion was felt. The truck driver (at a distance of 80 m or 270 feet) was caught in the flames and probably died immediately. The motorists and residents were outside the cloud but received serious bums. 

In-cloud overpressure is dependent on outflow velocity, orifice diameter, and the fuel s laminar burning velocity. 

Figure 4.7. Maximum overpressure in vapor cloud explosions after critical-flow propane jet release dependent on orifice diameter (a) undisturbed jet (b) jet into obstacles and confinement.

Although the experiments reported by Maurer et al. (1977) were performed for a completely different reason, namely, to study effects of vapor cloud explosions (see Section 6.4), fireballs were nevertheless generated. These experiments involved vessles of various sizes (0.226-1000 1) and containing propylene at 40 to 60 bar gauge pressure. The vessels were ruptured, and the released propylene was ignited after a preselected time lag. One of these tests, involving 452 kg of propylene, produced a fireball 45 m in diameter. 

A massive amount of propane is instantaneously released in an open field. The cloud assumes a flat, circular shape as it spreads. When the internal fuel concentration in the cloud is about 10% by volume, the cloud s dimensions are approximately 1 m deep and 100 m in diameter. Then the cloud reaches an ignition source at its edge. Because turbulence-inducing effects are absent in this situation, blast effects are not anticipated. Therefore, thermal radiation and direct flame contact are the only hazardous effects encountered. Wind speed is 2 m/s. Relative humidity is 50%. Compute the incident heat flux as a function of time through a vertical surface at 100 m distance from the center of the cloud. 

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