Tuesday, August 31, 2010

Book Review: Dust Explosions in the Process Industries, 3rd Edition

Fires and dust explosions are common and costly in many industries.  In this book Eckhoff has organized a comprehensive overview of his practical knowledge of the origin, development, prevention and mitigation of dust explosions, an up to date evaluation of testing methods, design measures and safe operating techniques.

Included are the research and findings of many other scientists, creating a definitive reference guide for information on the causes, effects and alternatives available for dealing with this complex subject, providing an excellent resource on dust explosions. This book will serve as a foundational reference on the subject of dust explosions in the process industries.  Also provided is detailed information of all phases of the hazard and control of a dust explosion. An invaluable reference.

-Jeff Nichols

As a resource to our valuable clients and readers, we provide the book review below from our colleague PUJAN AGNIHOTRI.

Mr. Agnihotri is an Associate Member of Society of Fire Protection Engineers (SFPE) & Member of National Fire Protection Association (NFPA), and research associate for

Book Review: Dust Explosions in the Process Industries, 3rd Edition                                                            

Published by: Gulf Professional Publishing, An Imprint of Elsevier Science
ISBN 0-7506-7602-7, Hardcover, 705 pages, 2003

Author: Rolf K. Eckhoff, Professor of Process Safety Technology, The University of Bergen, Norway.

One of the major challenge in the field of fire protection & life safety engineering in process industries is Dust Explosion. Dust explosions are common & costly for a wide range of industries such as food, pharmaceutical, paper & petrochemical. Thus it is important to emphasis on in depth study of dust explosion to avert any higher intensity disaster like Sugar Dust Explosion at Imperial Sugar Factory, Georgia, February 7, 2008. This publication provides great deal of knowledge for all audience, from layman to fire protection & life safety experts, keenly interested in learning more about the dust explosion. Author has done an excellent job in compiling, from various sources, a large volume of material relating to dust explosion.

This publication helps reader to gain theoretical & practical knowledge about the origin, development, prevention & mitigation of dust explosion. It is divided in nine chapters with nearly 750 pages with tables, graphs, derivations & illustrative figures, for thorough understanding about the subject: Dust Explosion. Author has used more than 300 references for each chapter of this book.  Author made some modification in his third edition of book; mainly a chapter on design of electrical equipment used in areas containing combustible dust, re-organized final review chapter with nearly 400 new literature references from years 1997-2002 & broad distribution of sections from the original chapters one to seven.

First chapter is an overview about the origin, propagation, prevention, & mitigation of dust explosion. Author in this chapter discuss about the nature of dust explosions, statistical records, importance of dust & dust cloud properties in explosion, methods involve in prevention & mitigation of dust explosion and their selection criteria. This chapter provides us basic understanding about the dust explosions.

Second chapter describe about the history of dust explosion accidents all over the world. Author discuss about dust explosion in flour warehouse, silo plant,  fish meal factory, large storage facilities, Linen Textile plant, coal dust plant, silicon powder grinding plant, slurry explosive factory, Aluminum powder production plant. He covers dust explosion accident events in United States, United Kingdom, Norway, Germany, Canada, China, Russia & Sweden, from years 1785 to 1989. Author provided references to reports of more recent accidents in Chapter 9. 

From chapter 3 the author starts exploring the different parameters affecting dust explosions.  In this chapter, he discusses the explosive concentration of dust cloud through reentrainment & redispersion of deposited dust in air. He gives us a detailed understanding about the forces & strength of dust particles in powder or dust deposits and effects of gaseous medium on dust particle flow. He ends this chapter by providing methods for generating experimental dust clouds for research purpose. 

Chapter 4 gives us information regarding flames movement in dust cloud. Author studies different parameters like burning velocities, flame thickness, quenching distances, rate of pressure rise (for closed vessel), explosible concentration, dimension of enclosure & temperatures for laminar, non- laminar & turbulent flame propagation of coal dust, organic dust, metal dust & miscellaneous dust particles, through various derivation.  At the end of the chapter, author emphasizes detonation propagation in dust clouds in air.

In chapter 5, the author discusses the ignition of dust clouds & dust deposits. He talks about the self heating & self ignition of dust deposits, and dust clouds ignition from different sources like electric spark, mechanical rubbing, grinding, or impact & hot surfaces. Important parameters like minimum ignition temperatures, minimum ignition energy or minimum electric spark ignition energy, activation energy, minimum self-ignition temperature, are discussed in detail in this chapter.

Chapter 6 describes information regarding the vent sizing required for dust explosions. Author provides vent sizing methods used in Europe & United States. Further he provided derivation for calculating vent area in accordance to L/D (effective length/ diameter of the vessel), Pred (maximum pressure development in vented deflagration), Pmax (expected maximum pressure in vented explosions). Chapter 7 deals with laboratory scale tests for different properties of dust.

Chapter 8 research & development on dust explosions from years 1997 to 2002 in Chapter 9 are added in this edition of book. Chapter 8 discusses electrical apparatus usage in combustible dust containing area. Classification of areas, details of electrical apparatus design criteria, prevention of dust from potential ignition sources, intrinsically safe electrical apparatus are the topics discussed in detail in chapter 8. Chapter 9 concentrates on research & development in dust explosion field throughout the globe, with references for major dust explosion accidents in history. 

Summarizing, I would recommend that this book is a key source of information for professionals dealing with combustible dust in their Industries.


Monday, August 23, 2010

Editorial | What to Do When Old Dust Collectors No Longer Comply With New Standards

As seen in Powder Bulk Solids, an excelent article by By Ed Ravert, United Air Specialists

Editorial | What to Do When Old Dust Collectors No Longer Comply With New Standards

Some Key Points:

*Although seemingly cost-effective for a company to hold onto a dust collection system for so many years, this may also be a potentially hazardous decision when it involves combustible dusts.

*Also noteworthy is the re-issue of the National Fire Protection Association’s NFPA 68 Standard on Explosion by Deflagration Venting. The completely revised Guideline is now a Standard that is enforceable by OSHA.

*Combustible Dust: What Is It?

*Options for Existing Equipment

*Staying Safe

If you are contemplating utilizing a used dust collector in a new application, I urge you to take a minute and click on the link above to read the rest of this article.

Tuesday, August 17, 2010

Inherent Safety = Lower Risks?

On his blog our friend Dr. Saraf asks: Inherent Safety = Lower Risks?

He is speaking of chemical processes, but this thinking can be applied to other industries and processes. For example, on a dust collection system, considering where you locate the fan and what type fan used, whether to return the air back to the plant, etc., can lead to an inherently safer design.

Recently a customer utilized a spark resistant fan on a wood dust closed loop relay system with light loading, thus reducing the need for additional spark detection and extinguishing systems in this particular design. The NFPA 664 Prescriptive design was to add Spark detection. By building the process safer, he was able to get his design approved by the local AHJ.

The rest of Dr. Saraf's blog post:
Chemical processes and designs are increasingly being evaluated for inherent safety - i.e. reduce the hazard rather than the risk. The philosophy behind inherent safety is ‘What You Don’t Have, Can’t Leak’ and so you take necessary steps to reduce the hazard.
Issues where inherently safer approaches can be successfully applied are fairly low, maybe 2%. Inherent safety framework suffers few major drawbacks - (a) not accounting for risk-benefit and (b) not providing acceptable risk criteria and a decision system to go along with it.
Eliminating hazards is may not always be practical as we know there is risk involved in every action. Even eating a burger.
Therefore as a matter of practicality, I recommend thinking of inherently safer alternative as lower risk option.
Within the framework of risk management, one can include evaluations of safer alternatives and be able to reach a decision.

Sunday, August 1, 2010

How To Conduct Effective Safety Training

Here is a slide show from Steve Wise, Sr. Mgr. Facilities at TTX Company, titled:

"How to Conduct Effective Safety Training"

He had posted on our LinkedIn Safety Training group page:

Topics include: How to get people to buy in and get involved, Safety Communication, Safety and Passion, etc.