Avoiding Static Ignition Hazards in Chemical Operations

Glossary......Page 0
Front Matter......Page 1
Preface......Page 3
Acknowledgments......Page 5
References......Page 7
Table of Contents......Page 18
1.1 Purpose......Page 25
1.2 Exclusions......Page 28
1.4 Organization of the Book......Page 29
2.1 What is Static Electricity?......Page 31
2.1.2 Magnitude of Current and Potential......Page 32
2.1.4 Importance of Trace Contaminants......Page 33
2.1.6 Statistics......Page 34
2.2 Charge Generation......Page 35
2.2.1 Induction Charging......Page 36
2.3 Charge Dissipation......Page 37
2.3.1 Variability of Conductivity......Page 39
2.4 Charge Accumulation......Page 40
2.5.1 Effective Energy......Page 41
2.6 Static Discharges......Page 44
2.6.1 Corona Discharge......Page 45
2.6.2 Brush Discharge......Page 47
2.6.3 Bulking Brush Discharge......Page 56
2.6.4 Spark Discharge......Page 59
2.6.5 Propagating Brush Discharge (PBD)......Page 62
2.6.6 Surface Streamer......Page 67
2.7.1 Body Capacitance and Resistance......Page 69
2.7.2 Voltage (V) and Energy (W) Attained......Page 70
2.7.3 Human Shock Response......Page 71
3.2 Hazard Identification Methods......Page 72
3.3.1 Conductive Objects......Page 73
3.4 Energy Estimates......Page 74
3.5.1 Charge......Page 75
3.5.2 Electric Field......Page 79
3.5.3 Potential......Page 82
3.5.4 Ignition Energy......Page 85
3.5.5 Conductivity of Liquids......Page 88
3.5.6 Resistivity of Solids......Page 89
3.5.7 Resistance......Page 90
3.8 Measuring the Effective Energy of Nonspark Discharges......Page 91
3.8.1 Gas Composition......Page 92
4.1.2 Purpose of Bonding and Grounding......Page 95
4.1.3 Resistance to Ground......Page 96
4.1.5 Ground Rods......Page 97
4.1.6 Grounding and Cathodic Protection......Page 98
4.2.1 Increase of Conductivity......Page 99
4.2.2 Charge Neutralizers......Page 100
4.3.1 Personnel Grounding......Page 102
4.3.3 Gloves......Page 104
4.4.1 Liquid Nitrogen/Liquid Air Hazards......Page 105
5.1.1 Flammable Liquid......Page 106
5.1.2 Flammable Limits......Page 109
5.1.3 Liquid Mist......Page 110
5.1.4 Minimum Ignition Energy (MIE)......Page 112
5.1.5 Explosion Prevention Systems......Page 118
5.2.1 Charge Generation......Page 119
5.2.3 Factors Influencing Charge Generation......Page 120
5.2.4 Charge Relaxation......Page 121
5.2.5 Classification of Liquids Based on Conductivity......Page 124
5.2.6 Antistatic Additives......Page 127
5.3.1 Metallic Piping Systems......Page 129
5.3.2 Nonconductive Pipe and Linings......Page 134
5.3.3 Flexible Hoses......Page 137
5.3.5 Filters and Relaxation Tanks......Page 139
5.3.6 Suspended Material......Page 141
5.3.7 Valves and Other Line Restrictions......Page 142
5.4 Filling Criteria for Tank Operations......Page 143
5.4.1 Storage Tanks......Page 145
5.4.2 Road Tankers......Page 151
5.4.4 Liquid Phase Mixers, Blenders, and Reactors......Page 155
5.4.5 Liquid–Solid Mixers, Blenders and Reactors......Page 158
5-4.6 Vacuum Trucks......Page 160
5.4.7 Plastic Tanks......Page 162
5.5.2 Sampling......Page 165
5.5.3 Gauging......Page 166
5.6.1 Water Washing......Page 167
5.6.2 Solvent Washing......Page 169
5.6.3 Steam Cleaning......Page 170
5.6.4 Acid Washing......Page 171
5.7.1 Metal Portable Tanks......Page 172
5.8 Portable Containers Less Than 60 Gallons Capacity......Page 173
5.8.1 All-Steel Drums......Page 174
5.8.2 Plastic Lined Drums......Page 176
5.8.4 Hand-Held Containers......Page 177
5.9.1 Clean Rooms......Page 180
5.9.3 Static Electrification In Gas Flow......Page 181
5.9.4 Ignition of Vented Gas......Page 182
5.9.5 Hazards of Plastic Sheet and Wrap......Page 183
5.9.6 Oxidant Enriched Atmospheres......Page 184
5.9.7 Elevated Temperature and Pressure......Page 185
5.9.8 Automotive and Marine......Page 186
5.9.9 Aerosol Spray Cans......Page 187
5.10.2 Screens In Hazardous Locations......Page 188
5.10.3 Static Dissipating Screen Overlays......Page 189
6.1 Flammability of Dust Suspensions......Page 190
6.1.1 Flammable Limits......Page 192
6.1.2 Minimum Ignition Energy (MIE) of Dust Suspensions......Page 193
6.1.3 Hybrid Mixtures......Page 195
6.1.4 Unstable or Energetic Powders......Page 198
6.1.5 Effect of Temperature on Ignition Energy......Page 199
6.2 Charging Mechanisms......Page 200
6.2.1 Charge Density......Page 202
6.2.2 Classification of Powders Based on Conductivity......Page 203
6.3.1 Charging in Pipeline Flow......Page 206
6.3.2 Special Grounding Cases......Page 210
6.4 Types of Static Discharge in Powder Systems......Page 212
6.4.1 Sparks......Page 213
6.4.2 Bulking Brush Discharges......Page 216
6.4.3 Propagating Brush Discharge......Page 217
6.5 General Operations......Page 218
6.5.1 Vacuum Trucks......Page 220
6.5.2 Bag Houses......Page 221
6.7 Flexible Intermediate Bulk Containers (FIBCs)......Page 222
6.7.1 Powder Transfers in Air Atmospheres......Page 223
6.7.3 Conductive and Antistatic FIBCs......Page 225
6.7.4 Vacuum FIBC Transfers......Page 227
A-2-6.5 Propagating Brush Discharge......Page 228
A-4-1.3 Resistance to Ground......Page 229
A-5-1.4.4 MIE of Liquid Mists......Page 232
A-5-2.4.1 Hyperbolic Relaxation......Page 234
A-5.3.5 Filtration......Page 236
A-5-4 Filling Criteria for Tank Operations......Page 237
A-5-4.2.1 Effect of Road Tires......Page 239
A-5-6.1 Potentials during Water Washing of Tanks......Page 240
A-6-1.3.1 Ignition Energy of Hybrid Mixtures......Page 242
A-6.1.5 Effect of Temperature on Powder MIE......Page 243
C......Page 245
E......Page 246
F......Page 247
G......Page 248
M......Page 249
P......Page 250
S......Page 251
U......Page 253
W......Page 254