Concentration failures

Instrument failure, pressure, flow, temperature, level or a reaction parameter, e.g. concentration. Failure of instrument air or electricity. 

At the interface alloy/electrolyte the concentration of the alloy components must be the same as in the bulk of the alloy. In aqueous electrolytes or in molten salts the less noble component might dissolve in the electrolyte and thus lead to concentration failures. This could be avoided by keeping up a small cathodic current preventing dissolution. The current may not distort the potential measurement. 

Chemical nature of pigment (1% concentration) Failure time (F ) (days) ... 

After setting up the test system, the inspeetor can fully concentrate on scanning the test zones. In the case of coupling failure, an acoustic alarm horn will sound and a visual alarm message will appear on the PC display. 

Place 2 ml. of the periodic acid reagent in a small test tube, add one drop (no more—otherwise the silver iodate, if formed, will fail to precipitate) of concentrated nitric acid, and shake well. Add one drop or a small crystal of the compound to be tested, shake the mixture for 15-20 seconds, and then add 1-2 drops of 3 per cent, silver nitrate solution. The instantaneous formation of a white precipitate of silver iodate is a positive test. Failure to form a precipitate, or the appearance of a brown precipitate which redissolves on shaking, constitutes a negative test. 

Ca " concentration, termed hypocalcemia, excitabihty increases. If this condition is not corrected, the symptoms of tetany, ie, muscular spasm, tremor, and even convulsions, can appear. Too great an increase in Ca " concentration, hypercalcemia, may impair muscle function to such an extent that respiratory or cardiac failure may occur. 

Tests using a constant stress (constant load) normally by direct tension have been described in ISO 6252 (262). This test takes the specimen to failure, or a minimum time without failure, and frequently has a flaw (drilled hole or notch) to act as a stress concentrator to target the area of failure. This type of testing, as well as the constant strain techniques, requires careful control of specimen preparation and test conditions to achieve consistent results (263,264). 

Resistance to Chemical Environments and Solubility. As a rule, amorphous plastics are susceptible, to various degrees, to cracking by certain chemical environments when the plastic material is placed under stress. The phenomenon is referred to as environmental stress cracking (ESC) and the resistance of the polymer to failure by this mode is known as environmental stress cracking resistance (ESCR). The tendency of a polymer to undergo ESC depends on several factors, the most important of which are appHed stress, temperature, and the concentration of the aggressive species. 

Sihcone contamination has been impHcated as a cause of failure in telephone switching systems and other devices that contain relay switch contacts (507). Analysis of airborne particulates near telephone switching stations showed the presence of siUcones at these locations. Where the indoor use of sihcones is intentionally minimised, outdoor levels were found to be higher than inside concentrations (508). Samples of particulates taken at two New Jersey office buildings revealed sihcone levels that were considerably higher indoors than outdoors. In these cases, indoor sihcone aerosols are beheved to be generated primarily by photocopiers, which use sihcone fuser oils. 

The total area under the curve A—D, shown as shaded in Figure 1, is the strain energy stored in a body. This energy is not uniformly distributed throughout the material, and it is this inequaUty that gives rise to particle failure. Stress is concentrated around the tips of existing cracks or flaws, and crack propagation is initiated therefrom (Fig. 2) (1). 

Water Treatment. Water and steam chemistry must be rigorously controlled to prevent deposition of impurities and corrosion of the steam cycle. Deposition on boiler tubing walls reduces heat transfer and can lead to overheating, creep, and eventual failure. Additionally, corrosion can develop under the deposits and lead to failure. If steam is used for chemical processes or as a heat-transfer medium for food and pharmaceutical preparation there are limitations on the additives that may be used. Steam purity requirements set the allowable impurity concentrations for the rest of most cycles. Once contaminants enter the steam, there is no practical way to remove them. Thus all purification must be carried out in the boiler or preboiler part of the cycle. The principal exception is in the case of nuclear steam generators, which require very pure water. These tend to provide steam that is considerably lower in most impurities than the turbine requires. A variety of water treatments are summarized in Table 5. Although the subtieties of water treatment in steam systems are beyond the scope of this article, uses of various additives maybe summarized as follows ... 

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