Dust Explosions in Factories - Precautions Required with Combustible Dusts
The dusts created by many materials in everyday use will explode if mixed with air in a cloud formation, and with a source of ignition present. This booklet desribes the problems created by the presence of explosible dusts that commonly occur in New Zealand workplaces.
Dust explosions can occur in grain silos and elevators, flour and icing sugar mills, malthouses, thermal coal dryers, milk spray-dryers and in those industries involved in the manufacture or processing of agricultural products, chemicals,coal, food products, metals, paper, pharmaceuticals, pigments, plastics, rubber and wood and related products.
One dust explosion in a Masterton plastics factory in 1965 killed four people and led to an amendment to the Factories Act 1946 to ensure factory occupiers take practicable steps to prevent such explosions.
Table of Contents
Introduction
What is a dust explosion?
Concentration of the dust cloud
Atmospheric composition
Ignition sources
Particle size of dusts
Hazard rating of dusts
Classification of hazardous locations for wiring
Specific points on dust control
Housekeeping
Elimination of ignition sources
Fire as a source of ignition
Spontaneous heating
Relief of explosion pressure
Sizing of explosion reliefs
Explosion relief vents
Explosion detection and suppression
Inerting
Strength
Rotary valves
Fire protection equipment and facilities
Further information
Appendix A: Hazard ratings of dust types
Appendix B: Dust explosions in New Zealand
Appendix C: The Masterton dust explosion
