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[en] After the law by decree of the 12. June 2003, N 233 (ATEX Directive) and REACH regulation (Regulation EC n. 2907/2006 of the European Parliament), several industrial fields, also not chemical, need the flammability data for the substances used. Perhaps, many of these data, especially for compounds with not common uses, are not easy to collect. It would be helpful to provide prediction methods in order to calculate these data without any experimentation that sometimes results time consuming, expensive and practically impossible for all the commercial compounds. In this research the ASTM software CHETAH (CHEmical Thermodynamic And Hazard evaluation) has been used in order to compute the lower flammability limit (Li), the limiting oxygen concentration (LOC, using nitrogen as inert gas) as a function of temperature, the adiabatic flame temperature Tflame, the fundamental burning velocity (Su), the quenching distance (Qd), the minimum ignition energy (MIE) for esters and ethers, substances highly used in industry.
[it]Con il recepimento del Decreto Legislativo 12 giugno 2003, N. 233 (Direttiva ATEX) e del regolamento REACH (Regolamento CE n. 1907/2006 del Parlamento Europeo) e sorta la necessita per i responsabili di molte attivita industriali, anche non chimiche, di disporre dei dati di infiammabilita per le sostanze utilizzate. Purtroppo, molti di questi dati, soprattutto per i composti d'impiego non comunissimo, non sono facilmente reperibili. Sarebbe quindi auspicabile poter disporre di idonei metodi previsionali per ricavare, gia sulla carta, questi dati senza ricorrere necessariamente alla sperimentazione, talvolta lunga e costosa e praticamente irrealizzabile per tutte le sostanze in commercio. In questo lavoro e stata utilizzata la versione 8 del software CHETAH (CHEmical Thermodynamic And Hazard evaluation) comercializzato dall'ASTM per calcolare il limite inferiore di infiammabilita Li dell'ossigeno di sicurezza MOC (con azoto come gas inerte) in funzione della temperatura, la temperatura adiabatica di fiamma Tfiamma, la velocita di propagazione della fiamma Su, la distanza di estinzione Qd, l'energia minima di innesco MIE di esteri ed eteri, importanti sostanze di notevole interesse industriale.
[en] Highlights: ► Fire/explosions are undesirable events in-process safety of matchhead composition. ► DSC and ARC were used to analyze the thermal decomposition of a matchhead composition. ► ARC studies evidence of onset of exothermic activity at 115.5 °C. ► Reactive potential was compared under adiabatic and isothermal conditions. ► Kinetic parameters were estimated for the thermal process observed in DSC and ARC. - Abstract: From the process safety point of view, irrespective of the kind of stimulus (friction, impact, heat), the final event is “thermal” in nature. Differential Scanning Calorimetry (DSC) and Accelerating Rate Calorimetry (ARC) were performed to understand thermal characteristics and kinetics of a matchhead composition. A single sharp and narrow exothermic transition occurred at 200, 210, 215 and 220 °C at different heating rates (5, 10, 15 and 20 °C min−1) suggesting that the matchhead composition was vulnerable to thermal hazard. ARC studies depicted onset temperature at 115.5 °C and a sharp rise in exothermic reaction at 127.64 °C within the time span of 14 s with the maximum heat release rate of 598.4 °C min−1. The exothermic activity resulted in rapid pressure rise (50.45 bar) confirming the vulnerability of this mixture to undergo catastrophic explosion. Kinetic parameters were estimated for the thermal process observed in DSC and ARC. Such data were validated
[en] This document qualitatively evaluates the FR-equency and consequences of DST and SST representative flammable gas accidents and associated represented hazardous conditions without controls. Based on the evaluation, it was determined that safety-significant SSCs and/or TSRs were required to prevent or mitigate flammable gas accidents. Controls were selected and the accidents re-evaluated taking credit for the controls
[en] This document identifies all interim safety equipment to be used for rotary mode core sampling of single-shell flammable gas tanks utilizing Rotary Mode Core Sampling systems (RMCS). This document provides the safety equipment for RMCS trucks HO-68K-4600, HO-68K-4647, trucks three and four respectively, and associated equipment. It is not intended to replace or supersede WHC-SD-WM-SEL-023, (Kelly 1991), or WHC-SD-WM-SEL-032, (Corbett 1994), which classifies 80-68K-4344 and HO-68K-4345 respectively. The term ''safety equipment'' refers to safety class (SC) and safety significant (SS) equipment, where equipment refers to structures, systems and components (SSC's). The identification of safety equipment in this document is based on the credited design safety features and analysis contained in the Authorization Basis (AB) for rotary mode core sampling operations in single-shell flammable gas tanks. This is an interim safety classification since the AB is interim. This document will be updated to reflect the final RMCS equipment safety classification designations upon completion of a final AB which will be implemented with the release of the Final Safety Analysis Report (FSAR)
[en] The release of a certain mass of fuel gas into the ambient atmosphere with negligible pressure difference whether deliberately or inadvertently results in the transient formation of flammable mixture zones for a period of time that represent a potential fire and explosion hazard. A numerical model based on the simultaneous solution of the equations of conservation of mass, momentum and energy has been developed to describe the development of such flammable zones when a finite quantity of fuel is released into the overlaying air within cylindrical vertical enclosures open to the outside atmosphere. Hydrogen disperses into the air extremely quickly with a strong temporal dependency on both horizontal and vertical directions. Comparison of the typical behavior of hydrogen dispersion with that of the lighter than air methane, the nearly buoyancy neutral ethylene and the much heavier than air propane is made. Some guidelines for reducing the fire and explosion hazards in such situations are presented. (authors)
[en] This book deals with hydrogen safety, which includes hydrogen safety program, hydrogen accident and damage statistics, characteristic of hydrogen safety and cases. It also mentions property of hydrogen such as general property, types of danger on hydrogen, ignition and flammability of hydrogen and leakage and spread of hydrogen, facility for hydrogen with safety, device and systems of hydrogen station hydrogen burning like Frank-Kamentskii theory, fire by hydrogen such as basics, types and jet fire, liquid hydrogen fire, blasting of hydrogen-air compound, deflagration to detonation transition, assessment of riskiness, hydrogen-etched and guideline for hydrogen safety.
[en] The major emphasis of this report is to describe what has been learned about the generation, retention, and release of flammable gas mixtures in high-level waste tanks. A brief overview of efforts to characterize the gas composition will be provided. The report also discusses what needs to be learned about the phenomena, how the Unreviewed Safety Question will be closed, and the approach for removing tanks from the Watch List
[en] Fluor Daniel Northwest was authorized to address flammable gas issues by reconciling the unexplained surface level increases in Tank 241-SX-105 (SX-105, typical). The trapped gas evaluation document states that Tank SX-105 exceeds the 25% of the lower flammable limit criterion, based on a surface level rise evaluation. The Waste Storage Tank Status and Leak Detection Criteria document, commonly referred to as the Welty Report is the basis for this letter report. The Welty Report is also a part of the trapped gas evaluation document criteria. The Welty Report contains various tank information, including: physical information, status, levels, and dry wells. The unexplained waste level rises were attributed to the production and retention of gas in the column of waste corresponding to the unaccounted for surface level rise. From 1973 through 1980, the Welty Report tracked Tank SX-105 transfers and reported a net cumulative change of 20.75 in. This surface level increase is from an unknown source or is unaccounted for. Duke Engineering and Services Hanford and Lockheed Martin Hanford Corporation are interested in determining the validity of unexplained surface level changes reported in the Welty Report based upon other corroborative sources of data. The purpose of this letter report is to assemble detailed surface level and waste addition data from daily tank records, logbooks, and other corroborative data that indicate surface levels, and to reconcile the cumulative unaccounted for surface level changes as shown in the Welty Report from 1973 through 1980. Tank SX-105 initially received waste from REDOX starting the second quarter of 1955. After June 1975, the tank primarily received processed waste (slurry) from the 242-S Evaporator/Crystallizer and transferred supernate waste to Tanks S-102 and SX-102. The Welty Report shows a cumulative change of 20.75 in. from June 1973 through December 1980
[en] The purpose of this study was to: (1) identify the more dominant design parameters that can serve as the quantitative measure of how prototypic a given melter is, (2) run the existing DWPF models to simulate the data collected using both DWPF and non-DWPF melter configurations, (3) confirm the validity of the selected design parameters by determining if the agreement between the model predictions and data is reasonably good in light of the design and operating conditions employed in each data set, and (4) run Computational Fluid Dynamics (CFD) simulations to gain new insights into how fluid mixing is affected by the configuration of melter internals and to further apply the new insights to explaining, for example, why the agreement is not good
[en] Safety hazards associated with the interim storage of a potentially flammable organic liquid in waste Tank C-103 are identified and evaluated. The technical basis for closing the unreviewed safety question (USQ) associated with the floating liquid organic layer in this tank is presented