Dust Explosion Zoning in Industrial Manufacturing Plants

In modern industrial production, explosion prevention and fire safety are critical priorities. Besides complying with fire protection standards, effective dust collection and control systems play a crucial role in minimizing explosion risks.

1. High-risk industries for dust explosions (Group 2)

Several industries are highly susceptible to dust explosion hazards due to the nature of their production processes:

Food production industries

• Flour production
• Flour-based products (instant noodles, bakery, confectionery, chocolate, cereals)
• Coffee production (beans, powder, instant coffee)
• Dairy production (milk powder, liquid milk)
• Cooking oil production

Other industrial sectors

• Veterinary pharmaceuticals
• Wood and furniture manufacturing
• Cement production
• Animal feed production
• Chemical and solvent industries
• Ceramics and pottery
• Paint production
• Plastic pipe manufacturing (PVC, uPVC, HDPE)

These industries share common characteristics:

• Fine, lightweight, powder-like dust
• Dust easily becomes airborne and difficult to control

Although most factories install central dust collection systems, localized dust emissions still occur in specific areas such as:

• Mixing zones
• Filling stations
• Packaging areas
• Grinding processes

These areas are the main sources of dust dispersion, and effective control at these points significantly reduces overall dust accumulation in the factory.

2. Classification of dust explosion zones in factories

Dust explosion zones are classified into three main categories according to ATEX standards (this article focuses on dust zones, not gas zones):

a. Zone 22

• Dust clouds are present infrequently and for short periods
• Occurs under abnormal conditions
• Explosion risk exists when dust mixes with air

Typical areas:

• Near equipment with dust leakage
• Grinding rooms, mixing areas

Occurrence time:
Less than 10 hours per year

b. Zone 21

• Dust clouds are present occasionally during normal operation
• Sufficient dust concentration to form explosive mixtures

Typical areas:

• Near powder feeding systems
• Areas where dust layers can become airborne

Occurrence time:
More than 10 hours per year

c. Zone 20

• Dust clouds are present continuously or for long periods
• High concentration of combustible dust

Typical areas:

• Inside machinery and equipment
• Dust storage containers

Occurrence time:
More than 1000 hours per year

Conclusion

Understanding and properly classifying dust explosion zones (Zone 20, 21, 22) is essential for:

• Selecting the right ATEX-certified equipment
• Implementing effective dust control systems
• Ensuring worker safety and operational reliability

Proper zoning helps reduce explosion risks and ensures compliance with industrial safety standards.