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Power handling and electrostatics
Book reviews
Powder
handling
and electrostatics
Thomas B. Jones and Jack L. King Lewis Publishers, 714881, $59.95
Chelsea, Michigan,
This rather slender book was written to provide a source of safe practices for the avoidance of electrostatic discharges (ESD) in the processing, bulking and shipping of plastic powders and chemicals used in their manufacture. One of the authors had worked at Xerox Corporation in this field before becoming an academic, and the other author still works in the plastics industry. They have written this book for practising engineers and plant technicians who work in polymer processing or manufacturing facilities where plastic powders are used. The book contains six main chapters, an annotated bibliography and six appendices. Chapter 1 is of an introductory nature, briefly discussing the probabilistic nature of electrostatic ignition hazards and its relationship to dust explosion hazards in general. In Chapter 2, relevant principles of electrostatics applied to bulked and flowing powders are reviewed. Topics include powder charged phenomenology, charge separation and dissipation, and
Understanding
USA, 1st Ed., 1991, 103pages,
the various types of electrostatic discharges. Techniques to measure intrinsic and extrinsic properties of powders relevant to ESD hazards are described in Chapter 3. These are tests for specific charge, resistivity and charge relaxation time, electrostatic fields and potentials, and detection of ESD activity. Chapter 4 discusses a number of miscellaneous issues relevant to plastic resin processing and handling. The topics include ESD-induced minimum ignition condirions, particle size effects, charge dissipation, ESD hazards of level indicators in hoppers and silos, dense-phase pneumatic conveying hazards, coronainduced product degradation, and use of conductive fibres in filter bags and liners in shipping containers. Several dust explosion case histories are presented in Chapter 5, while Chapter 6 lists a number of ‘dos and don’&’ for abatement of electrostatic hazards. The final chapter is an annotated bibliography which contains a good number of useful reference
and controlling
ISBN0873
articles and books. The six appendices succinctly cover a number of useful topics. Appendices A, B and C contain a summary of technical data and practical information concerning electrostatic hazards associated with dusts. Appendix D contains a monograph which can be used for capacitance discharge risk assessment (including examples). A set of questions and answers, covering some of the questions most often asked about polymer powders and the electrostatic hazards they pose, are presented in Appendix E. Appendix F contains an exhaustive listing of explosion characteristics of various dusts compiled from various Bureau of Mines reports. Although this book is primarily slanted towards ESD hazards in handling powders used in the plastics industry, it contains useful information applicable to all types of explosible dusts. Stanley S. Grossel Hofjinan-La Roche Inc., Ndey, New Jersey, USA
static electricity
Gunter Luttgens and Martin Glor Expert Verlag GmbH, Ehningen bei Boblingen, ISBN 3 8169 0.510 2, DM76
This book is an excellent English translation of the earlier book published in German. The authors are both internationally known authorities in this field. The book comprises nine chapters which provide basic information that will assist production and design engineers as well as process safety and loss prevention specialists in analysing and controlling potential electrostatic problems. Chapter 1 reviews the basic physical concepts involved in electrostatic phenomena, such as charge, surface and space charge density, potential, voltage etc. Each physical quantity is summarized systematically. The summary con-
Germany,
1st Ed., 1989,226
tains information regarding the definition, unit, symbol, properties, and relationships to other quantities, and examples from industrial practice. This format provides a simple yet effective way of understanding these concepts. Correlations between various phenomena in an electric field are discussed in Chapter 2. The relation between charge, potential and electric field are developed by means of geometric representations (field mapping). In Chapter 3, a thorough explanation is presented on how electrostatic charging actually occurs. Such phenomena as electron work function, Helmholtz interface, and charge separation are described,
pages,
and the major portion of the chapter is devoted to a discussion of how to reduce the disposition for electrostatic charging. A discussion of measurements related to electrostatics is presented in Chapter 4. Various methods and instrnments are reviewed, and a list of British and German standards is included. The four main types of gas discharge (spark, brush, corona and propagating brush discharge) are thoroughly described in Chapter 5. A very useful part of this chapter is the inclusion of sections describing the occurrence of these types of discharge in industrial practice. Chapter 6 is an excellent overview
J. Loss Prev. Process Ind., 1992, Vol5, No 4
253
Powder
handling
and electrostatics
Thomas B. Jones and Jack L. King Lewis Publishers, 714881, $59.95
Chelsea, Michigan,
This rather slender book was written to provide a source of safe practices for the avoidance of electrostatic discharges (ESD) in the processing, bulking and shipping of plastic powders and chemicals used in their manufacture. One of the authors had worked at Xerox Corporation in this field before becoming an academic, and the other author still works in the plastics industry. They have written this book for practising engineers and plant technicians who work in polymer processing or manufacturing facilities where plastic powders are used. The book contains six main chapters, an annotated bibliography and six appendices. Chapter 1 is of an introductory nature, briefly discussing the probabilistic nature of electrostatic ignition hazards and its relationship to dust explosion hazards in general. In Chapter 2, relevant principles of electrostatics applied to bulked and flowing powders are reviewed. Topics include powder charged phenomenology, charge separation and dissipation, and
Understanding
USA, 1st Ed., 1991, 103pages,
the various types of electrostatic discharges. Techniques to measure intrinsic and extrinsic properties of powders relevant to ESD hazards are described in Chapter 3. These are tests for specific charge, resistivity and charge relaxation time, electrostatic fields and potentials, and detection of ESD activity. Chapter 4 discusses a number of miscellaneous issues relevant to plastic resin processing and handling. The topics include ESD-induced minimum ignition condirions, particle size effects, charge dissipation, ESD hazards of level indicators in hoppers and silos, dense-phase pneumatic conveying hazards, coronainduced product degradation, and use of conductive fibres in filter bags and liners in shipping containers. Several dust explosion case histories are presented in Chapter 5, while Chapter 6 lists a number of ‘dos and don’&’ for abatement of electrostatic hazards. The final chapter is an annotated bibliography which contains a good number of useful reference
and controlling
ISBN0873
articles and books. The six appendices succinctly cover a number of useful topics. Appendices A, B and C contain a summary of technical data and practical information concerning electrostatic hazards associated with dusts. Appendix D contains a monograph which can be used for capacitance discharge risk assessment (including examples). A set of questions and answers, covering some of the questions most often asked about polymer powders and the electrostatic hazards they pose, are presented in Appendix E. Appendix F contains an exhaustive listing of explosion characteristics of various dusts compiled from various Bureau of Mines reports. Although this book is primarily slanted towards ESD hazards in handling powders used in the plastics industry, it contains useful information applicable to all types of explosible dusts. Stanley S. Grossel Hofjinan-La Roche Inc., Ndey, New Jersey, USA
static electricity
Gunter Luttgens and Martin Glor Expert Verlag GmbH, Ehningen bei Boblingen, ISBN 3 8169 0.510 2, DM76
This book is an excellent English translation of the earlier book published in German. The authors are both internationally known authorities in this field. The book comprises nine chapters which provide basic information that will assist production and design engineers as well as process safety and loss prevention specialists in analysing and controlling potential electrostatic problems. Chapter 1 reviews the basic physical concepts involved in electrostatic phenomena, such as charge, surface and space charge density, potential, voltage etc. Each physical quantity is summarized systematically. The summary con-
Germany,
1st Ed., 1989,226
tains information regarding the definition, unit, symbol, properties, and relationships to other quantities, and examples from industrial practice. This format provides a simple yet effective way of understanding these concepts. Correlations between various phenomena in an electric field are discussed in Chapter 2. The relation between charge, potential and electric field are developed by means of geometric representations (field mapping). In Chapter 3, a thorough explanation is presented on how electrostatic charging actually occurs. Such phenomena as electron work function, Helmholtz interface, and charge separation are described,
pages,
and the major portion of the chapter is devoted to a discussion of how to reduce the disposition for electrostatic charging. A discussion of measurements related to electrostatics is presented in Chapter 4. Various methods and instrnments are reviewed, and a list of British and German standards is included. The four main types of gas discharge (spark, brush, corona and propagating brush discharge) are thoroughly described in Chapter 5. A very useful part of this chapter is the inclusion of sections describing the occurrence of these types of discharge in industrial practice. Chapter 6 is an excellent overview
J. Loss Prev. Process Ind., 1992, Vol5, No 4
253