210 resultados para LIGHTNING ARRESTERS


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Natural hazards affecting industrial installations could directly or indirectly cause an accident or series of accidents with serious consequences for the environment and for human health. Accidents initiated by a natural hazard or disaster which result in the release of hazardous materials are commonly referred to as Natech (Natural Hazard Triggering a Technological Disaster) accidents. The conditions brought about by these kinds of events are particularly problematic, the presence of the natural event increases the probability of exposition and causes consequences more serious than standard technological accidents. Despite a growing body of research and more stringent regulations for the design and operation of industrial activities, Natech accidents remain a threat. This is partly due to the absence of data and dedicated risk-assessment methodologies and tools. Even the Seveso Directives for the control of risks due to major accident hazards do not include any specific impositions regarding the management of Natech risks in the process industries. Among the few available tools there is the European Standard EN 62305, which addresses generic industrial sites, requiring to take into account the possibility of lightning and to select the appropriate protection measures. Since it is intended for generic industrial installations, this tool set the requirements for the design, the construction and the modification of structures, and is thus mainly oriented towards conventional civil building. A first purpose of this project is to study the effects and the consequences on industrial sites of lightning, which is the most common adverse natural phenomenon in Europe. Lightning is the cause of several industrial accidents initiated by natural causes. The industrial sectors most susceptible to accidents triggered by lightning is the petrochemical one, due to the presence of atmospheric tanks (especially floating roof tanks) containing flammable vapors which could be easily ignited by a lightning strike or by lightning secondary effects (as electrostatic and electromagnetic pulses or ground currents). A second purpose of this work is to implement the procedure proposed by the European Standard on a specific kind of industrial plant, i.e. on a chemical factory, in order to highlight the critical aspects of this implementation. A case-study plant handling flammable liquids was selected. The application of the European Standard allowed to estimate the incidence of lightning activity on the total value of the default release frequency suggested by guidelines for atmospheric storage tanks. Though it has become evident that the European Standard does not introduce any parameters explicitly pointing out the amount of dangerous substances which could be ignited or released. Furthermore the parameters that are proposed to describe the characteristics of the structures potentially subjected to lightning strikes are insufficient to take into account the specific features of different chemical equipment commonly present in chemical plants.

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Principals. Lightning is one of the most powerful and spectacular natural phenomena. Lightning strikes to humans are uncommon but can cause devastating injuries. We analyzed lightning-related admissions to our emergency department from January 2000 to December 2010 to review and highlight the main features of lightning-related injuries. Methods. All data were collected prospectively and entered in the emergency department' database (Qualicare Switzerland) and retrospectively analyzed. Results. Nine patients with lightning-related injuries presented to our emergency department. Four were female, and five were male. The most common site of injury was the nervous system (6 out of 9 patients) followed by the cardiovascular system (5 out of 9 patients). The third most common injuries occurred to the skin (3 out of 9 patients). Four of the patients had to be hospitalized for further observation. Conclusion. Reports of lightning strikes and related injuries are scarce. The establishment of an international register would therefore benefit the understanding of their injury patterns and facilitate specific treatment.

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The transient response of a system of independent electrodes buried in a semi-infinite conducting medium is studied. Using a simple and versatile numerical scheme written by the authors and based on the Electric Field Integral Equation (EFIE), the effect caused by harmonic signals ranging on frequency from Hz to hundred of MHz, and also by lightning type driving signal striking at a remote point far from the conductors, is extensively studied. The value of the scalar potential appearing on the electrodes as a function of the frequency of the applied signal is one of the variables investigated. Other features such as the input impedance at the injection point of the signal and the Ground Potential Rise (GPR) over the electrode system are also discussed

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Mode of access: Internet.

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"List of books referred to, or consulted, relating to ... lightning conductors" : p. xi-xv. Appendix, "Bibliography of works bearing upon lightning conductors" : p. [231]-248.

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Mode of access: Internet.

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Mode of access: Internet.

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"IEMA, American Red Cross, [and] NOAA, US Department of Commerce, National Oceanic and Atmospheric Administration"

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Mode of access: Internet.

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Mainly a reprint from papers by Sir W. Snow Harris.