Dust Explosion and Fire Prevention Handbook

A Guide to Good Industry Practices

Nicholas P. Cheremisinoff

• Publisher: Wiley-Scrivener
• Year: 2014
• Print ISBN: 9781118773505
• eBook ISBN: 9781118773789
• Edition: 1
• Topic: Physical Sciences
• Subtopic: Industrial & Technical Chemistry

Up-to-date and thorough coverage of the causes, repercussions, and prevention of dust explosions and fires by one of the most well-respected environmental scientists and worker safety litigation specialists in the world

This handy volume is a ready "go to" reference for the chemical engineer, plant manager, process engineer, or chemist working in industrial settings where dust explosions could be a concern, such as the process industries, coal industry, metal industry, and others. Though dust explosions have been around since the Earth first formed, and they have been studied and written about since the 1500s, they are still an ongoing concern and occur almost daily somewhere in the world, from bakeries to fertilizer plants.

Dust explosions can have devastating consequences, and, recently, there have been new industrial standards and guidelines that reflect safer, more reasonable methods for dealing with materials to prevent dust explosions and resultant fires. This book not only presents these new developments for engineers and managers, it offers in-depth coverage of the subject, starting with a complete overview of dust—how it forms, when it is in danger of exploding, and how this risk can be mitigated—as well as a general overview of explosions and the environments that foster them.

Dust Explosion and Fire Prevention Handbook covers individual industries, such as metal and coal; offers an appendix that outlines best practices for preventing dust explosions and fire and how these risks can be systematically mitigated by these implementations; and incorporates a handy glossary of terms for easy access, not only for the veteran engineer or chemist, but for the student or new hire.

This ready reference is one of the most useful texts that an engineer or chemist could have at their side. With so many accidents still occurring in industry today, this must-have volume pinpoints the most common, sure-fire ways for engineers, scientists, and chemists working with these hazardous materials to go about their daily business safely, efficiently, and profitably, with no extraneous tables or theoretical treatises.

Chapter 1

Combustible Dusts

1.1 Introduction

According to the National Safety Council¹, dust is defined as “solid particles generated by handling, crushing, grinding, rapid impact, detonation, and decrepitation of organic or inorganic materials, such as rock, ore, metal, coal, wood, and grain.” Dust is a by-product of different processes that include dry and powdery material conveying, solids crushing and screening, sanding, trimming of excess material, tank and bin feeding and storing of granular materials, and a number of other processes. The creation of dust during material handling and processing operations may pose the obvious problem of inhalation risks to workers, often characterized as chronic or long term worker exposures. However, when combustible dust is produced and allowed to accumulate, risks can create immediate danger to life and health from explosions. Combustible dust explosions have resulted in the loss of life, multiple injuries and substantial property and business damage. A few examples² are:

• In 2002, an explosion at Rouse Polymerics International, a rubber fabricating plant in Vicksburg, Miss., resulted in injuring eleven employees, five of whom later died of severe burns. The explosion occurred with the ignition of an accumulation of a highly combustible rubber.
• In 2003 an explosion and fire occurred at the West Pharmaceutical Services plant in Kinston, N.C., resulting in the death of six workers, injuries to dozens of employees, and hundreds of job losses due to the destruction of the plant. The facility produced rubber stoppers and other products for medical use. The fuel for the explosion was a fine plastic powder that had accumulated unnoticed above a suspended ceiling over the manufacturing area.
• In 2003 an explosion and fire damaged the CTA Acoustics manufacturing plant in Corbin, Ky., fatally injuring seven employees. The facility produced fiberglass insulation for the automotive industry. The combustible dust associated with the explosion was a phenolic resin binder used in producing fiberglass mats.
• In 2003, a series of explosions severely burned three employees, one fatally, and caused property damage to the Hayes Lemmerz manufacturing plant in Huntington, Ind. The Hayes Lemmerz plant manufactured cast aluminum automotive wheels. The explosions were fueled by aluminum dust, a combustible by-product of the manufacturing process.
• In 2008 combustible sugar dust was the fuel for a massive explosion and fire at the Imperial Sugar Co. plant in Port Wentworth, Ga., resulting in 13 deaths and the hospitalization of 40 more workers, some of whom received severe burns.

These are only a few examples of dust explosions in which there was loss of life and the substantial destruction of assets and properties.

Before we can understand the causes of dust explosions and ways to prevent them, we need to understand what dust is. The physical, chemical and thermodynamic properties of dust are important for a myriad of reasons ranging from the protection of workers from inhalation hazards, explosions and fire, and the overall safe and economic handling of materials that are prone to creating dust.

In this chapter we focus on the physical and thermodynamic properties of particles which comprise dust. Properties such as size, shape, particle size distribution and the combustible nature of some materials are discussed, orienting the reader to more in-depth discussions to follow in later chapters.

1.2 Metrics

Dusts are generated from solid or granular materials and can exist over a wide range of particle sizes depending on the material handling and processing operation. They may also form through the processes of sublimation and thermal oxidation as well as from combustion-related processes. Particles that are too large to remain airborne settle out due to gravity, while the smallest particles can remain suspended in air almost indefinitely as colloidal suspensions.

The unit of measure used to characterize dust particle size is the ‘micrometer’, more commonly known as a micron or μm. The micrometer is a unit of length equal to 10⁻⁴ (0.0001) centimeter or approximately 1/25,000 of an inch, or another way of stating this – there are 25,400 microns in one inch. In metric units a micron represents one-millionth of a meter. By way of physical comparisons:

• Red blood cells are typically 8 μm (0.0008 cm) in size
• Human hair is 50 – 600 μm in diameter
• Cotton fiber, 15–30 μm

The human eye can see particles to as low as 40 microns. Table 1.1 provides some typical dimensions for materials the reader may relate to.

However, the term particle size requires some thought. What do we really mean by particle size? Certainly when a particle is spherical, size equates with the diameter of a sphere. But particles not only come in different sizes, they exist in different shapes.

Table 1.1 Typical particle size comparisons.

Particle Descriptor	Particle Size (microns)
	Low Range	Upper Range
Oxygen	0.00050
Carbon Dioxide	0.00065
Atmospheric Dust	0.001	40
Viruses	0.005	0.3
Rosin Smoke	0.01	1
Tobacco Smoke	0.01	4
Oil Smoke	0.03	1
Smoldering or Flaming Cooking Oil	0.03	0.9
Sea Salt	0.035	0.5
Coal Flue Gas	0.08	0.2
Clay	0.1	50
Corn Starch	0.1	0.8
Paint Pigments	0.1	5
Radioactive Fallout	0.1	10
Face Powder	0.1	30
Metallurgical Dust	0.1	1,000
Metallurgical Fumes	0.1	1,000
Burning Wood	0.2	3
Carbon Black Dust	0.2	10
Combustion-related – motor vehicles, wood burning, open burning, industrial processes	2.5
Bacteria	0.3	60
Copier Toner	0.5	15
Insecticide Dusts	0.5	10
Talcum Dust	0.5	50
Asbestos	0.7	90
Calcium Zinc Dust	0.7	20
Anthrax	1	5
Smoke from Synthetic Materials	1	50
Yeast Cells	1	50
Milled Flour, Milled Corn	1	100
Auto and Car Emission	1	150
Coal Dust	1	100
Fiberglass Insulation	1	1,000
Fly Ash	1	1,000
Lead Dust	2
Spider web	2	3
Mold	3	12
Spores	3	40
Cement Dust	3	100
Starches	3	100
Bone Dust	3	300
Iron Dust	4	20
Red Blood Cells	5	10
Gelatin	5	90
Coffee	5	400
Grain Dusts	5	1,000
Antiperspirant	6	10
Mustard	6	10
Textile Dust	6	20
Tea Dust	8	300
Mold Spores	10	30
Fertilizer	10	1,000
Ground Limestone	10	1,000
Pollens	10	1,000
Textile Fibers	10	1,000
Cayenne Pepper	15	1,000
Ginger	25	40
Saw Dust	30	600
Human Hair	40	600
Mist	70	350
Dust Mites	100	300
Beach Sand	100	10,000
Spanish Moss Pollen	150	750
dot (.)	615
Glass Wool	1,000
Eye of a Needle	1,230
one inch	25,400

1.3 Size and Shape

One of the most important physical properties of particulates is size. Particle size measurement is routinely carried out across a wid...

Table of contents

• Cover
• Half Title page
• Title page
• Copyright page
• About the Author
• Preface
• Chapter 1: Combustible Dusts
• Chapter 2: The Basics of Dust Explosions
• Chapter 3: Factors Influencing Dust Explosibility
• Chapter 4: Explosion Prevention in Grain Dust Elevators
• Chapter 5: Coal Dust Explosibility and Coal Mining Operations
• Chapter 6: Preventing Fires and Explosions Involving Metals
• Chapter 7: Phlegmatization, Diluent Dusts, and the Use of Inert Gases
• Chapter 8: Augmenting Risk Mitigation with Leak Detection and Repair
• Appendix A: General Guidelines on Safe Work Practice
• Glossary of Terms
• Index