Local high temperature

The ambient temperature of the installation will affect the cable rating, and account should be taken of any local high temperatures caused by proximity of process plant, the presence of and location of other cables and any thermal insulation, which may prevent or inhibit heat dis-... 

The arc resistance of a polymer is the length of time for which we can apply an electrical discharge to its surface before it breaks down and begins to conduct electricity. Breakdotvn typically takes the form of conductive carbonaceous tracks that are caused by oxidation due to locally high temperatures. Polymers -with lowpolarity typically fare better in this test than polar polymers. Arc resistance is reduced by dirt, moisture, and other surface contaminants. 

A 45 kl tank of sulfate turpentine from a paper mill became dangerously heated, owing to oxidation arising from local high temperature and an air-purging procedure. 

Several studies attempted to determine whether chemical reactions were occurring at the aluminum-water interface. The finding that there was some light emission and local high temperatures led to the conclusion that reactions do occur, and they may be of more importance in the more violent explosions. 

Identification of hot spots. Localized overheating of a tube causes localized high-temperature creep. This leads to the plastic deformation of a tube, and hence thin tube walls. Such hot spots are indicated by the color of the tube, as shown in Table 21.1. This chart is not a function of... 

Among the possibilities are the effect of the weather and atmospheric pollution on the properties of the exposed surfaces of components. They will become roughened and will adsorb increasing amounts of moisture and conductive impurities. Surface discharges may occur which will result in further deterioration due to local high temperatures and the sputtering of metallic impurities from attached conductors. 

The temperatures at which solids, in the compact form, will ignite in air without the application of any spark or other local high temperature, have occasionally been determined. The following arc a few of the better-known results (p. 117). 

Exceptional results were obtained in a test on naphtha reformer catalyst which utilized a continuous catalyst regeneration section. In this type of service, it is possible for a graphitic carbon deposit to build up over a period of time. This form of carbon does not regenerate easily. When is does burn, the localized high temperatures generated can collapse the catalyst structure resulting in a low surface area inactive pellet. 

To provide channels for the removal of polishing debris and heat from the pad surface so as to reduce the possibility of scratch and generation of other defects due to the debris accumulation on the pad surface and to avoid rapid chemical reaction at localized high temperature regions due to frictional and chemical reaction heat ... 

In these studies, the possibility exists that the kinetics of gas formation have been modified or that they require a different mechanism of localized interaction within the macrostructure. The larger, more amorphous the structure, the greater the opportunity for product ratio inversion by the localized high temperature power input to specific bond types. Presently, gas output and composition are being studied as a function of shale grade, time, and power. Tentative results indicate the individual hydrocarbon components maintain a consistent relationship to each other but the C02 and CO content vary with grade of shale and time. 

The problem suggested by these data is whether radiation annealing is due to the local high temperatures in the hot spots or to the enhanced probability of recombination owing to the increased supply of ions, free radicals, or electrons produced hy the radiation. 

Alternatively, for vessels up to 101, an electric heating band (barrel heater) may be used, having a power of approximately 30 W of reactor volume. In no case should heating rods or tubes inside the reactor be used, because localized high temperatures, aggravated by the low stirring rate, will cause unfavourable medium alterations and cell damage. 

The heat transfer through the electrolyte can be influenced by local hydrodynamic flows (by convection) or by changing the heat conductivity of the electrolyte. The first strategy can be implemented by adding the appropriate tool-electrode motion such as vibration or rotation. Both do not only promote the heat transfer but also the local high-temperature chemical etching of the workpiece as discussed in Section 7.2. 

Unlike chemical reactions, tribochemical reactions are triggered by frictional force, resulting in wear. Tribochemical wear can be seen as one type of corrosive wear. When the corrosion is activated by mechanical interactions between the contacting surfaces, it produces activated surface sites and localized high temperatures sufficient for chemical reaction. Tribochemical wear involves surface charging of electrons, surface passivation, and surface film removal processes. 

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