AS/NZS 4745:2004

1 - AS/NZS 4745:2004 CODE OF PRACTICE FOR HANDLING COMBUSTIBLE DUSTS
4 - PREFACE
5 - CONTENTS
7 - FOREWORD
8 - SECTION 1 SCOPE AND GENERAL
8 - 1.1 SCOPE
8 - 1.2 APPLICATION
8 - 1.3 REFERENCED DOCUMENTS
11 - SECTION 2 PHILOSOPHY
11 - 2.1 OCCUPATIONAL HEALTH AND SAFETY MANAGEMENT SYSTEM
11 - 2.1.1 Awareness of regulations and responsibility
11 - 2.1.2 Occupational health and safety legislation
12 - 2.1.3 Duty of care
12 - 2.1.4 Occupational health and safety management system model
12 - 2.2 RISK MANAGEMENT STANDARDS
13 - 2.2.1 Risk management philosophy
13 - 2.2.2 Hazard identification
14 - 2.2.3 Risk analysis
14 - 2.2.4 Risk evaluation
14 - 2.2.5 Risk control
15 - 2.2.6 Monitoring of risk
15 - 2.2.7 Independent audits of the risk management system
15 - 2.3 TRAINING
15 - 2.4 DOCUMENTATION
16 - SECTION 3 HAZARD ASSESSMENT
16 - 3.1 DUST CHARACTERIZATION
16 - 3.1.1 Introduction
16 - 3.1.2 Chemical composition
16 - 3.1.3 Moisture
17 - 3.1.4 Particle size distribution and shape (specific surface area)
17 - 3.2 SAFETY CHARACTERISTICS OF DUSTS
18 - 3.3 COMBUSTION BEHAVIOUR
18 - 3.3.1 Smouldering
18 - 3.3.2 Flaming combustion
18 - 3.3.3 Exothermic decomposition
18 - 3.3.4 Dust explosions
19 - 3.3.5 Atmospheric influences
19 - 3.3.6 Gas release
19 - 3.4 DETERMINATION OF DUST CHARACTERISTICS
21 - 3.4.1 Dust layers
23 - 3.4.2 Airborne dust/air mixtures
24 - 3.4.3 Minimum ignition energy (MIE)
25 - 3.4.4 Minimum ignition temperature (MIT)
25 - 3.4.5 Test requirements
25 - 3.5 SAMPLING OF DUSTS FOR TESTING
26 - 3.6 HAZARDOUS PROCESSES
26 - 3.6.1 Introduction
27 - 3.6.2 Filling and emptying operations
27 - 3.6.3 Loading bulk materials into flammable solvents
27 - 3.6.4 Flexible intermediate bulk containers (FIBC)
27 - 3.6.5 Mixing
27 - 3.6.6 Dust separation
27 - 3.6.7 Spray and fluidized bed dryers
27 - 3.6.8 Milling
27 - 3.6.9 Sifters and sieves
28 - 3.6.10 Pneumatic conveyors
28 - 3.6.11 Belt conveyors
28 - 3.6.12 Vibratory conveyors
28 - 3.6.13 Bucket elevators
28 - 3.6.14 Screw feeders
28 - 3.6.15 Transport of containers
28 - 3.6.16 Vehicles
29 - 3.6.17 Storage in vessels, silos and bunkers
29 - 3.6.18 Exhaust equipment
29 - 3.6.19 Vacuum cleaners
29 - 3.7 RISK ASSESSMENT
29 - 3.7.1 Consequence assessment
32 - 3.7.2 Chemical composition
33 - SECTION 4 SAFETY REQUIREMENTS
33 - 4.1 GENERAL
33 - 4.2 TRAINING/AWARENESS
33 - 4.3 PERSONNEL PROTECTIVE EQUIPMENT (PPE)
34 - 4.4 SITE ENTRY CONDITIONS
34 - 4.5 WORK PERMITS
34 - 4.6 SAFETY OPERATING PROCEDURES
35 - 4.7 MAINTENANCE AND HOUSEKEEPING
35 - 4.7.1 Maintenance
35 - 4.7.2 Housekeeping
37 - SECTION 5 DETERMINING THE PRESENCE OF EFFECTIVE IGNITION SOURCES
37 - 5.1 GENERAL
37 - 5.2 HOT SURFACES
38 - 5.3 FLAMES, HOT GASES AND HOT PARTICLES
38 - 5.4 MECHANICALLY GENERATED SPARKS
38 - 5.5 ELECTRICAL APPARATUS
39 - 5.6 STRAY ELECTRIC CURRENTS, INDUCED VOLTAGES AND CATHODIC CORROSION PROTECTION
39 - 5.7 STATIC ELECTRICITY
40 - 5.8 LIGHTNING
40 - 5.9 RADIOFREQUENCY (RF) ELECTROMAGNETIC WAVES FROM 10 4 Hz TO 3x10 12 Hz
40 - 5.10 ELECTROMAGNETIC WAVES FROM 3 (10 11 Hz TO 3 x 10 15 Hz (Infra-red, visible and ultraviolet light)
40 - 5.11 IONIZING RADIATION
41 - 5.12 ULTRASONIC RADIATION
41 - 5.13 ADIABATIC COMPRESSION AND SHOCK WAVES
41 - 5.14 EXOTHERMIC REACTIONS, INCLUDING SELF-IGNITION OF DUSTS
44 - SECTION 6 PLANT DESIGN
44 - 6.1 SITE AND PLANT LAYOUT
44 - 6.2 BUILDING DESIGN
45 - 6.3 EQUIPMENT
45 - 6.3.1 Dust containment
45 - 6.4 REDUCE DUST CLOUD FORMATION
45 - 6.4.1 Equipment selection
46 - 6.4.2 Equipment design considerations
46 - 6.4.3 Industry specific issues
46 - 6.5 EXPLOSION-PREVENTION AND PROTECTION
46 - 6.5.1 Fundamental principles
47 - 6.5.2 Avoidance or reduction of the amount of substances that can form combustible dust atmospheres
49 - SECTION 7 DETAILED DESIGN AND OPERATIONAL ISSUES
49 - 7.1 CLASSIFICATION OF HAZARDOUS PLACES
49 - 7.1.1 General
49 - 7.1.2 Zones for dusts
50 - 7.2 DESIGN AND CONSTRUCTION OF EQUIPMENT, PROTECTIVE SYSTEMS AND COMPONENTS BASED ON THE AVOIDANCE OF IGNITION SOURCES
50 - 7.2.1 General
50 - 7.2.2 Classification for levels of protection
51 - 7.2.3 General requirements for avoidance of ignition sources
52 - 7.2.4 Hot surfaces
52 - 7.2.5 Flames and hot gases
53 - 7.2.6 Mechanically generated sparks, embers and hot particles
54 - 7.2.7 Electrical apparatus
54 - 7.2.8 Stray electric currents and cathodic corrosion protection
54 - 7.2.9 Static electricity
55 - 7.2.10 Lightning
55 - 7.2.11 Radiofrequency (RF) electromagnetic waves from 10 4 Hz to 3 x 10 12 Hz
56 - 7.2.12 Electromagnetic waves from 3 x 10 11 Hz to 3 x 10 15 Hz (Infra-red, visible and ultraviolet light)
56 - 7.2.13 Ionizing radiation
57 - 7.2.14 Ultrasonic radiation
58 - 7.2.15 Adiabatic compression and shock waves
58 - 7.2.16 Exothermic reactions, including self-ignition of dusts
59 - 7.3 DESIGN AND CONSTRUCTION OF EQUIPMENT, PROTECTIVE SYSTEMS AND COMPONENTS TO REDUCE THE EXPLOSION EFFECTS
59 - 7.3.1 General
59 - 7.3.2 Explosion-resistant design
61 - 7.3.3 Explosion relief venting
66 - 7.3.4 Combined pressure resistant and vented designs
66 - 7.3.5 Explosion suppression
69 - 7.3.6 Prevention of explosion propagation (explosion decoupling)
72 - 7.3.7 Ember and spark extinguishing systems
73 - 7.4 PROVISIONS FOR EMERGENCY MEASURES
73 - 7.5 PROVISIONS FOR PLANT START-UP
74 - 7.6 PRINCIPLES OF MEASURING AND CONTROL SYSTEMS FOR EXPLOSION-PREVENTION AND PROTECTION
74 - 7.7 FIRE FIGHTING
76 - SECTION 8 EMERGENCY MANAGEMENT
76 - 8.1 PURPOSE
76 - 8.2 EMERGENCY PLANNING
76 - 8.2.1 Emergency procedures
76 - 8.2.2 Roles, responsibilities and actions
78 - APPENDIX A - TOOLS FOR USE IN POTENTIALLY EXPLOSIVE ATMOSPHERES
79 - APPENDIX B - MEASURING AND CONTROL SYSTEMS TO AVOID IGNITION SOURCES
80 - APPENDIX C - BIBLIOGRAPHY
81 - GLOSSARY

Outlines measures and practices to assist those industries which may have risks associated with the presence of combustible dusts as part of their processes; it also assists such industries in minimizing the risk of injury, death or loss of property to fire and/or explosion through the application of good design and management principles and practices in the construction, operation and maintenance of manufacturing and processing plants and associated transportation and storage systems.

This Code of Practice is intended to apply whenever combustible dusts are encountered in quantities sufficient to give rise to a fire and/or explosion. This would normally include, but is not limited to, manufacturing plants and processes (where dusts may be generated or used as part of the process) and bulk storage and handling installations. It provides a means by which relevant parties can firstly determine whether or not risks exist within an existing or a proposed system or facility, secondly ascertain the nature of such risks, and thirdly determine the means by which the criteria for safe design, construction, operation and maintenance can be met. The Code is not intended to apply to parts of pulverized fuel combustion systems, or other systems where burning is intended. Where other applicable Standards and Codes exist for the design, construction, operation and maintenance of those systems they may be adopted.

First published as AS/NZS 4745:2004.