Electrical safety explosions

Hazard, i.e. the potential of the material to cause injury under certain conditions (flammability, explosion limits in air, ignition and autoignition temperatures, static electricity (explosions have occurred during drying due to static electricity), dust explosion, boiling point, fire protection (specification of extinguishers, compounds formed when firing), R S (nature of special risk and safety precautions). Table 5.2-5 lists hazards associated with typical chemical reactions. 

Cooper, W. F. and Jones, D. A. (1993) Electrical Safety Engineering, 3rd edn (Butterworth-Heinemann). Cox, S. and Tait, R. (1998) Safety, Reliability and Risk Management—An Integrated Approach (Elsevier). Cross, J. and Farrer, D. (1982) Dust Explosions (Plenum Press). 

Column selection high performance liquid chromatography Electrical safety in the laboratory Flammable and explosive Instrumentation of HPLC (slide show and discussion)... 

J. M. Ellis, J. V. Evans and W. R. Simons, The repair and overhaul of electrical apparatus for use in potentially explosive atmospheres - a new code of practice. Electrical safety in hazardous environments. lEE Conference 1 to 3 December 1982. Conference Publication No. 218, pages 54 to 59. IEEE Savoy Place, London, WC2 OBL ISBN 0 852-96267-3... 

Check proximity of flammable materials to any potential ignition sources. Open flames and devices that generate sparks should not be near fiammables. Pay special attention to devices placed in fume hoods that do not meet National Electrical Safety Code (U.S. DOC, 1993) Division 1, Group C and D explosion-resistance specifications for electrical devices. Stirrers, hot plates, Variacs, heat tape, outlet strips, ovens (all types), refrigerators, flame sources (e.g., flame ionization detectors (FIDs) and atomic absorption spectrometers), and heat guns constitute the majority of devices that do not typically conform to these code requirements (see section 8.C.6.1). 

NFPA 68, Explosion Protection by Deflagration Venting NFPA 69, Standard on Explosion Prevention Systems NFPA 70, National Electrical Code NFPA 70E, Standard for Electrical Safety in the Workplace NFPA 101, Life Safety Code... 

Caution should be used when storing, operating, or repairing a battery because of the chemical, explosive, and electrical safety hazards associated with all batteries. 

Behavioral observation and discussion Confined space Critical task analysis Critical task procedures Damage control Electrical safety Emergency preparedness Ergonomics Explosives... 

A. F. Schlack, "Susceptibihty of Electric Primers and Electrostatic Discharges" ia Minutes of the 15th Explosives Safety Seminar, AD-775 580, NTIS, Spriugfield, Va., 1973. 

Plant Safety. Of the many ferroalloy products produced in electric furnaces, ferromanganese has the greatest potential for furnace emptions or the more serious furnace explosions. The severity of the explosions increases with the size of the furnace. Such incidents are infrequent, but can occur, and when they do are often disastrous. Explosions usually result in extensive damage to the furnace and surrounding area, and often severe injuries or death to personnel in the immediate area. An emption is the sudden ejection of soHds, Hquids, or gases from the furnace interior. A more violent and instantaneous ejection of material, accompanied by rapid expansion of burning gas, is considered an explosion (38). 

Rotating electrical machines starting performance of single-speed three-phase cage induction motors for voltages up to and including 690 V Electrical apparatus for explosive gas atmosphere. Increased safety protection e 8789/1996 6381/1991 BS EN 60034-12/1996 BS 5501-6/1977... 

Electrical apparatus for explosive gas atmospheres. Increased safety motors. General requirements 6181/1991 BS 5501-6/1977 -... 

AMD 1 Electrical apparatus for potentially explosive atmospheres- Intrinsic safety i (AMD 10040J dated June 1998. Read with BS EN 50014 1993... 

Bee.iusa the nitrogen pressure was unreliable, it was difficult to maintain a pressure of 0.5 inch water gauge in the metal cabinet. Workers complained that the safety switch kept isolating the electricity supply, so an electrician reduced the setpoint first to 0.25-inch and then to zero, thus effeciocly bypassing the switch. The setpoint could not be seen unless the cover of the switch was removed and the electrician told no one what he had done. The workers though I lie wa,s a good electrician who had prevented spurious trips. Solvent and air leaked into the cabinet, as ilready described, and the next time the electricity supply was switched there was an explosion. 

An explosion and fire (March 13, 1991) occurred at an ethylene oxide unit at Union Carbide Chemicals Plastics Co. s Seadrift plant in Port Lavaca, TX, 125 miles southwest of Houston. The blast killed one, injured 19, and idled the facility, that also produces ethylene, ethylene glycol, glycol ether ethanolamines, and polyethylene. Twenty-five residents were evacuated for several hours as a safety precaution. The plant lost all electrical power, for a few days, because its cogeneration unit was damaged. The Seadrift plant, with 1,600 workers, is capable of making 820 million lb per year of ethylene oxide which is one-third of Carbide s worldwide production of antifreeze, polyester fibers, and surfactants Seadrift produces two thirds of Carbide s worldwide production of polyethylene. 

Buildings erected must be adequate witli respect to explosion venting and ventilation, firewalls, exits, drainage, and electrical wiring. The safety of the equipment and the structures is often a function of tlieir age. Tlie degree of "adequacy" must be evaluated based on tliis as well as the factors above. 

The key to safety in explosives manufacturing is to use isolated high-velocity nitric acid reactors that have only a veiy small hold up at any one time (that is, only a small amount of dangerous material is held up inside the reactor at any time). Units are widely spaced, so any accident involves only small amounts of explosive and does not propagate through the plant. Fire and electrical spark hazards are rigorously controlled, and manpower reduced to the absolute minimum through automation. 

These explosions in air are usually the result of the release of flammable gas and/or mists by leaks, rupture of equipment, or rupture of safety relierdng devices and release to the atmosphere, which become ignited by spark, static electricity, hot surfaces, and many other... 

Energy Efficient (EE) Motor Designs, 628 NEMA Design Classifications, 630 Classification According to Size, 630 Hazard Classifications Fire and Explosion, 631 Electrical Classification for Safety in Plant Layout, 647 Motor Enclosures, 649 ... 

Inspection by independent persons or bodies for safety purposes goes back to the middle of the nineteenth century. At that time, the focus of concern was the explosion of steam boilers, and this hazard was most prevalent in the textile industry. Consequently, a group of public-spirited individuals formed the Manchester Steam Users Association for the Prevention of Boiler Explosion. This body carried out boiler examinations and later added insurance as an inducement to the plant owners. By the beginning of the twentieth century steam and gas engines and electrical machines had been added, followed by lifts, cranes and hoisting machines. 

Laboratories working frequently with flammables, such as in extraction processes, may set aside a separate room for such work for maximum safety. Ideally, this room should have explosion-proof electrical equipment and special ventilation. Rigid work rules should be enforced, such as requiring workers to leave matches and lighters on a shelf outside before entering. Installation of conductive flooring should be considered, and steel tools should be prohibited at times when work is in progress. 

Withdrawn) 1989 AMD 3 Code of practice for selection, installation and maintenance of electrical apparatus for use in potentially explosive atmospheres (other than mining applications or explosives processing and manufacture). Part 1 General recommendations (AMD 7871) dated 15 September 1993. Withdrawn, superseded by BS EN 60079-14 1997 (Withdrawn) 1978 AMD 1 Code of practice for selection, installation and maintenance of electrical apparatus for use in potentially explosive atmospheres (other than mining applications or explosives processing and manufacture). Part 6 Recommendations for type of protection. Increased safety (AMD 5557) dated 30 November 1989. Withdrawn, superseded by BS EN 60079... 

The worst hazard scenarios (excessive temperature and pressure rise accompanied by emission of toxic substances) must be worked out based upon calorimetric measurements (e.g. means to reduce hazards by using the inherent safety concept or Differential Scanning Calorimetry, DSC) and protection measures must be considered. If handling hazardous materials is considered too risky, procedures for generation of the hazardous reactants in situ in the reactor might be developed. Micro-reactor technology could also be an option. Completeness of the data on flammability, explosivity, (auto)ignition, static electricity, safe levels of exposure, environmental protection, transportation, etc. must be checked. Incompatibility of materials to be treated in a plant must be determined. 

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