Burst diameter

FIGURE 15.109 Typical departure diameters and burst diameters for bubbles formed in nucleate boiling in annular flow (from Sun et al. [272], with permission from Taylor Francis, Washington, DC. All rights reserved). 

Bursting tests have been carried out on neatly a hundred thick-walled cylinders made of carbon, low alloy, and stainless steels, together with some nonferrous materials. The diameter ratio of the cylinders varied from 1.75 to 5.86, and some tests were carried out at 660°C. An analysis of the results (19) showed that 90% of the cylinders burst within 15% of the value given by equation 17. 

Fiber dimensions have been studied for hemodialysis. When blood is circulated through the fiber lumen (m vivo), a significant reduction in apparent blood viscosity may occur if the flow-path diameter is below 100 p.m (11). Therefore, current dialy2ers use fibers with internal diameters of 180—250 p.m to obtain the maximum surface area within a safe range (see Dialysis). The relationship between the fiber cross section and the blood cells is shown in Figure 5. In many industrial appUcations, where the bore fluid is dialy2ed under elevated pressure (>200 kPa or 2 atm), fibers may burst at points of imperfection. Failure of this nature is especially likely for asymmetric fibers that display a large number of macro voids within the walls. 

The term mist generally refers to liquid droplets from submicron size to about 10 /xm. If the diameter exceeds 10 /xm, the aerosol is usually referred to as a spray or simply as droplets. Mists tend to be spherical because of their surface tension and are usually formed by nucleation and the condensation of vapors (6). Larger droplets are formed by bursting of bubbles, by entrainment from surfaces, by spray nozzles, or by splash-type liquid distributors. The large droplets tend to be elongated relative to their direchon of mohon because of the action of drag forces on the drops. 

In fact, the vent on the tank was choked. The gauge air pressure (75 psi or 5 bar) was sufficient to burst the tank (design gauge pressure 5 psi or 0.3 bar). Originally the tank had a 6-in.-diameter vent. But at some time this was blanked off, and a 3-in.-diameter dip branch was used instead as the vent. 

In another case, a 4i -in.-diameter pipe carrying a mixture of hydrogen and hydrocarbons at a gauge pressure of 3,600 psi (250 bar) and a temperature of 350 00°C burst, producing a jet of name longer than 30 m (Figure 9-12). Fortunately, the pipe was located high up, and no one was injured. 

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.)... 

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. 

Figure 4.19. Diameters of side-on overpressure circles for various explosive yields (1 ton 2000 lb) (based on free-air bursts).

Figure 7-9D. Protection against two different pressures from opposite directions using graphite disks, such as in ciosed storage tanks. Particularly API-type to guard against failure of primary breathers, conservation vents, etc. These require a differential of at least 10 psig between the two burst ratings, depending on diameters of disks. By pemnission. Continental Disc Corporation.

The Code requires that the disks be burst on test by one of three methods using four sample disks, but not less than 5% from each lot. Figure 7-32 illustrates test results for burst pressure versus temperature of a disk design, all fabricated from the same material, and of the same diameter. 

The ruptured or burst disk on a vessel or pipe system presents a pressure drop to flow at that point, and it can be estimated by assuming the disk is a flat plate orifice [37] wdth a discharge coefficient, K[Pg.459]

Nanotechnology has led to very efficient versions of liposomes. Tiny hollow spheres only nanometers in diameter hold even tinier capsules of medicine. The spheres are made of silica covered with gold nanoparticles and when they are coated with antibodies they attach to tumor cells. The spheres are sensitive to light of specific wavelengths and when the light is applied, either heat up and destroy the tumor, or burst, releasing the drugs within the capsules directly into the tumor. 

Most patients have a mixture of non-in-flamed and inflamed lesions. Inflamed lesions can be superficial or deep, and arise from non-inflamed lesions. The superficial lesions are usually papules and pustules (5 mm or less in diameter), and the deep lesions are large pustules and nodules. Papules are small, raised, red spots, while pustules are predominantly yellow (Figs. 11.3,11.4). Pustules frequently start as solid lesions, like papules, which soon liquefy. Usually, the roof of the pustule bursts, allowing the pus to escape. The pustule represents a par-... 

Particularly high stress occurs when bubbles burst on the surface of the liquid, whereby droplets are eruptive torn out of the surface [32-36]. According to theoretical calculations, maximum energy densities occur in the region of the boundary surface shortly before the droplets separate [36]. The results calculated by Boulton-Stone and Blake [34] show that these are exponentially dependent on bubble diameter dg. Whereas these authors found values of e = lO mVs with dg = 0.5 mm, these are only e 1 m /s with dg = 5 mm. The situation may be different regarding the droplet volume separated from the surface by the gas throughput and thus the number of particles which are exposed to high stress. The maximum for this value occurs with a bubble diameter of dg = 4 mm (see [34]), and it is therefore feasible that there could be an optimal bubble size. 

Figure 14.10 illustrates the method of seismic prospecting on land by what is known as reflection shooting. A hole usually 10 to 12 cm in diameter is drilled to a depth of 15 to 30 m. The charge of explosive is likely to be 5 to 12-5 kg and the stemming used is usually water. As the explosive must fire under a depth of water which may exceed 45 m, special varieties of gelatines are employed (see p. 53). Alternatively, a powder explosive can be sealed into pressure-resistant metal containers. Special detonators are also employed, not only to withstand the possible head of water, but also to have a specially short bursting time (see p. 113). 

A drum of graphite with magnesium and uranium, stored underwater with a 6mm diameter relief hole, burst and scattered its contents. This was attrributed to insufficient venting of hydrogen evolved by reaction of magnesium and water [1], If the uranium was present as metal, it seems likely to have been an even more potent source of hydrogen [2],... 

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