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AS/NZS 4745:2012
[Pending Revision]Code of practice for handling combustible dusts
Sets out good design and management principles and practices for the construction, operation and maintenance of manufacturing and processing plants and associated transportation and storage systems.
Published: 10/10/2012
Pages: 74
Table of contents
Cited references
Content history
Table of contents
Header
About this publication
Preface
1 Scope and general
1.1 Scope
1.2 Application
1.3 Referenced documents
1.4 Definitions
2 OHS and risk management
2.1 Occupational health and safety management system
2.1.1 Awareness of regulations and responsibility
2.1.2 Occupational health and safety legislation
2.1.3 Duty of care
2.1.4 Occupational health and safety management system model
2.2 Risk management Standards
2.3 Training
2.4 Records
3 Hazard assessment
3.1 Dust characterization
3.1.1 Introduction
3.1.2 Chemical composition
3.1.2.1 General
3.1.2.2 The influence of composition on explosion characteristics
3.1.2.3 Further information
3.1.3 Moisture
3.1.4 Particle size distribution and shape (specific surface area)
3.2 Safety characteristics of dusts
3.3 Combustion behaviour
3.3.1 Smouldering
3.3.2 Flaming combustion
3.3.3 Exothermic decomposition
3.3.4 Dust explosions
3.3.4.1 General
3.3.4.2 Dust deflagration
3.3.4.3 Detonations
3.3.4.4 Primary and secondary explosions
3.3.5 Atmospheric influences
3.3.6 Gas release
3.4 Determination of dust characteristics
3.4.1 General
3.4.2 Dust layers
3.4.2.1 Combustion rating
3.4.2.2 Minimum ignition temperature (glowing temperature)
3.4.2.3 Exothermic reaction in an air stream (relative auto-ignition temperature)
3.4.2.4 Exothermic decomposition (oxygen lean conditions)
3.4.2.5 Exothermic decomposition under temperature controlled conditions
3.4.2.6 Differential scanning calorimetry
3.4.2.7 Impact sensitivity
3.4.2.8 Electrical resistivity
3.4.3 Airborne dust/air mixtures—Deflagration parameters in a near spherical closed vessel (20 litre or greater)
3.4.4 Minimum ignition energy (MIE)
3.4.5 Minimum ignition temperature (MIT)
3.4.6 Test requirements
3.5 Sampling of dusts for testing
3.6 Hazardous processes
3.6.1 Introduction
3.6.2 Filling and emptying operations
3.6.3 Loading bulk materials into flammable solvents
3.6.4 Flexible intermediate bulk containers (FIBC)
3.6.5 Mixing
3.6.6 Dust separation
3.6.7 Spray and fluidized bed dryers
3.6.8 Milling
3.6.9 Sifters and sieves
3.6.10 Pneumatic conveyors
3.6.11 Belt conveyors
3.6.12 Vibratory conveyors
3.6.13 Bucket elevators
3.6.14 Screw feeders
3.6.15 Transport of containers
3.6.16 Vehicles
3.6.17 Storage in vessels, silos and bunkers
3.6.18 Exhaust equipment
3.6.19 Vacuum cleaners
3.7 Risk assessment
3.7.1 Consequence assessment
3.7.1.1 General
3.7.1.2 Size of fire
3.7.1.2.1 Fire spread through equipment
3.7.1.2.2 Release from vents
3.7.1.2.3 Release from combustible fittings
3.7.1.2.4 Impingement on adjacent equipment
3.7.1.2.5 Thermal effects
3.7.1.2.6 Secondary explosions
3.7.1.3 Overpressure effects
3.7.1.4 Effect on supports
3.7.1.5 Effects as a result of venting
3.7.1.6 Missiles
3.7.1.6.1 Failure of containment
3.7.1.6.2 Operation of vents
3.7.1.6.3 As a result of overpressure waves
3.7.1.7 Toxic gas release
3.7.1.8 Asphyxiation hazard
3.7.2 Chemical composition
4 Safety requirements
4.1 General
4.2 Training/Awareness
4.3 Personnel protective equipment (PPE)
4.4 Site entry conditions
4.5 Work permits
4.6 Safety operating procedures
4.7 Maintenance and housekeeping
4.7.1 Maintenance
4.7.2 Housekeeping
5 Determining the presence of effective ignition sources
5.1 General
5.2 Hot surfaces
5.3 Flames, hot gases and hot particles
5.4 Mechanically generated sparks
5.5 Electrical apparatus
5.6 Stray electric currents, induced voltages and cathodic corrosion protection
5.7 Static electricity
5.8 Lightning
5.9 Radiofrequency (RF) electromagnetic waves from 104 Hz to 3 × 1012 Hz
5.10 Electromagnetic waves from 3 × 1011 Hz to 3 × 1015 Hz (Infra-red, visible and ultraviolet light)
5.11 Ionizing radiation
5.12 Ultrasonic radiation
5.13 Adiabatic compression and shock waves
5.14 Exothermic reactions, including self-ignition of dusts
6 Plant design
6.1 Site and plant layout
6.2 Building design
6.3 Equipment—Dust containment
6.3.1 Dust containment
6.4 Reduce dust cloud formation
6.4.1 Limit the fall
6.4.2 Equipment selection
6.4.3 Equipment design considerations
6.4.3.1 General
6.4.3.2 Structural strength
6.4.3.3 Burst strength
6.4.3.4 Avoiding sparks
6.4.3.5 Seal bearings
6.4.4 Industry specific issues
6.5 Explosion-prevention and protection
6.5.1 Fundamental principles
6.5.2 Avoidance or reduction of the amount of substances that can form combustible dust atmospheres
6.5.2.1 General
6.5.2.2 Substitution or modification of substances that are capable of forming combustible dust atmospheres
6.5.2.3 Limitation of concentration
6.5.2.4 Inerting
7 Detailed design and operational issues
7.1 Classification of hazardous areas
7.1.1 General
7.1.2 Zones for dusts
7.2 Design and construction of equipment, protective systems and components based on the avoidance of ignition sources
7.2.1 General
7.2.2 Classification for levels of protection
7.2.3 General requirements for avoidance of ignition sources
7.2.4 Hot surfaces
7.2.5 Flames and hot gases
7.2.6 Mechanically generated sparks, embers and hot particles
7.2.7 Electrical apparatus
7.2.8 Stray electric currents and cathodic corrosion protection
7.2.9 Static electricity
7.2.10 Lightning
7.2.11 Radiofrequency (RF) electromagnetic waves from 104 Hz to 3 × 1012 Hz
7.2.12 Electromagnetic waves from 3 × 1011 Hz to 3 × 1015 Hz (Infra-red, visible and ultraviolet light)
7.2.13 Ionizing radiation
7.2.14 Ultrasonic radiation
7.2.15 Adiabatic compression and shock waves
7.2.16 Exothermic reactions, including self-ignition of dusts
7.3 Design and construction of equipment, protective systems and components to reduce the explosion effects
7.3.1 General
7.3.2 Explosion-resistant design
7.3.2.1 General
7.3.2.2 Explosion-pressure-resistant design
7.3.2.3 Explosion-pressure-shock-resistant design
7.3.3 Explosion relief venting
7.3.4 Combined pressure resistant and vented designs
7.3.5 Explosion suppression
7.3.6 Prevention of explosion propagation (explosion decoupling)
7.3.6.1 General
7.3.6.2 Extinguishing barriers
7.3.6.3 Rapid-action valves and flaps
7.3.6.4 Rotary valves
7.3.6.5 Explosion diverters
7.3.6.6 Double valves
7.3.6.7 Chokes (product as a barrier)
7.3.6.8 Devices for hybrid mixtures
7.3.6.9 Deflagration arresters
7.3.6.10 Detonation arresters
7.3.6.11 Flashback preventers
7.3.7 Ember and spark extinguishing systems
7.4 Provisions for emergency measures
7.5 Provisions for plant start-up
7.6 Principles of measuring and control systems for explosion-prevention and protection
7.7 Firefighting
8 Emergency management
8.1 Purpose
8.2 Emergency planning
8.2.1 Emergency procedures
8.2.2 Roles, responsibilities and actions
Appendix A
Appendix B
Amendment control sheet
AS/NZS 4745:2012
Amendment No. 1 (2013)
Correction
Cited references in this standard
[Current]
Explosion protection systems - Part 1: Determination of explosion indices of combustible dusts in air
VDI 3673.1
Sheet 1 Pressure venting of dust explosions
VDI 2263
Dust fires and dust explosions; hazards, assessment, protective measures
NFPA 69
Standard on Explosion Prevention Systems
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