Thin rupture

The speed of wetting has been measured by running a tape of material that is wetted either downward through the liquid-air interface, or upward through the interface. For a polyester tape and a glycerol-water mixture, a wetting speed of about 20 cm/sec and a dewetting speed of about 0.6 cm/sec has been reported [37]. Conversely, the time of rupture of thin films can be important (see Ref. 38). 

The rupture process of a soap film is of some interest. In the case of a film spanning a frame, as in Fig. XIV-15, it is known that rupture tends to originate at the margin, as shown in the classic studies of Mysels [207, 211]. Rupture away from a border may occur spontaneously but is usually studied by using a spark [212] as a trigger (a-radia-tion will also initiate rupture [213]). An aureole or ridge of accumulated material may be seen on the rim of the growing hole [212, 214] (see also Refs. 215, 216). Theoretical analysis has been in the form of nucleation [217, 218] or thin-film instability [219]. 

Fig. 6. Force profile obtained from a one nanosecond simulation of streptavidin-biotin rupture showing a series of subsequent force peaks most of these can be related to the rupture of individual microscopic interactions such as hydrogen bonds (bold dashed lines indicate their time of rupture) or water bridges (thin dashed lines).

Rupture Disks A rupture disk is a device designed to function by the bursting of a pressure-retaining disk (Fig. 26-15). This assembly consists of a thin, circular membrane usually made of metal, plastic, or graphite that is firmly clamped in a disk holder. When the process reaches the bursting pressure of the disk, the disk ruptures and releases the pressure. Rupture disks can be installed alone or in combination with other types of devices. Once blown, rupture disks do not reseat thus, the entire contents of the upstream process equipment will be vented. Rupture disks are commonly used in series (upstream) with a relief valve to prevent corrosive fluids from contacting the metal parts of the valve. In addition, this combination is a reclosing system. 

A rupture dise is a simple deviee that essentially eonsists of a thin material held in plaee between two flanges. The dise is usually made of metal, although it may be made of other materials. The ehoiee of material is important beeause the rupture dise must be designed to elose toleranees to operate properly. During emergeney venting, the dise ruptures when the pressure level rises to a ehosen level. The vessel is then vented and the pressure in the vessel eventually drops... 

These are thin diaphragms held between flanges and calibrated to burst at a specified static inlet pressure. Unlike relief valves, rupture discs cannot reseal when the pressure declines. Once the disc ruptures, any flow into the vessel will exit through the disc, and the disc must be replaced before the pressure vessel can be placed back in service. Rupture discs are manufactured in a variety of materials and with various coatings for concision resistance. 

G. Reiter. Unstable thin polymer films rupture and dewetting process. Langmuir 9 1344-1351, 1993. 

R. Yershalmi-Rozen, J. Klein, L. J. Fetters. Suppression of rupture in thin non-wetting liquid films. Science 262 793-795, 1994. 

Z3 Pneumatic 1- Catastrophic a. Leakage 0 - 1/4 b. Leakage >1/4 c. Rupture 2- Degraded 3- Incipient a. Wall Thinning b. Embritllament c. Cracked or Rawed... 

A rupture disk is a non-reclosing thin diaphragm (metal, plastic, carbon/graphite (non-metallic)) held between flanges and designed to burst at a predetermined internal pressure. Each bursting requires the installation of a new disk. It is used in corrosive service, toxic or leak-proof applications, and for required bursting pressures not easily accommodated by the conventional valve such as explosions. It is applicable to steam. 

In view of its position in the e.m.f. series ( °aj3+/ai = 166V (SHE)), aluminium would be expected to be rapidly attacked even by dilute solutions of relatively weak acids. In fact, the rate of chemical attack is slow, owing to the presence on the aluminium of a thin compact film of air-formed oxide. When a voltage is applied to an aluminium anode there is a sudden initial surge of current, as this film is ruptured, followed by a rapid fall to a lower, fairly steady value. It appears that this is due to the formation of a barrier-layer. Before the limiting thickness is reached, however, the solvent action of the electrolyte initiates a system of pores at weak points or discontinuities in the oxide barrier-layer. 

Extremely thin, glassy silicate scales of less than eggshell thickness may sufficiently insulate the tubes of WT boilers and the furnace tube of FT boilers for tube failure to occur through deformation and rupture. 

As flow velocities increase, chelant attack becomes substantially worse, with the flow pattern being reflected in the form of U-shaped depressions and long tails (comet tails). Thinning continues until boiler failure occurs through a rupture of the thinned metal surface. In areas of high stress and/or high turbulence, attack is greatly enhanced and may be very localized. 

Foam persistence increases with rise in BW TDS because the bubbles are stabilized by the combined repelling forces of electrical charges at the steam-water interface that result from the high concentration of dissolved salts. The repulsion effect of similar charges prevents bubble thinning, bubble rupture and coalescence mechanisms from taking place. 

This equation is based on the assumption that pseudoplastic (shear-thinning) behaviour is associated with the formation and rupture of structural linkages. It is based on an experimental study of a wide range of fluids-including aqueous suspensions of flocculated inorganic particles, aqueous polymer solutions and non-aqueous suspensions and solutions-over a wide range of shear rates (y) ( 10 to 104 s 1). 

Reiter, G. (1993) Unstable thin polymer films Rupture and dewetting processes. Langmuir, 9, 1344-1351. 

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