Combustible Dust Classifications

Classifying combustible dust and the unique types of incidents that go along with them is a relatively new science. To make matters more difficult for the people who want this information, the literature that has the OSHA definitions of these dusts, such as NFPA 499: Recommended Practice for the Classification of Combustible Dusts and of Hazardous Locations for Electrical Installations in Chemical Process Areas are sometimes classified.

The OSHA Website mentions “organic” and “metal” classifications, but the information isn’t very extensive. There are two other ways to classify combustible dust explosions. The first is by the material the dust is composed of, common materials and the distribution of combustible incidents by material are as follows:

• Food – 23% of incidents
• Wood – 24% of incidents
• Metal – 20% of incidents
• Plastic – 14% of incidents
• Coal – 8% of incidents
• Other Inorganic Material – 4% of incidents
• Other Organic Material – 7% of incidents

Another way to classify them is by the industry in which they occur. Here are the most common industries, as well as the distribution of combustible dust incidents across them:

• Food Products – 24% of incidents
• Lumber & Wood Products – 15% of incidents
• Chemical Manufacturing – 12% of incidents
• Primary Metal Industries – 8% of incidents
• Rubber & Plastic Products – 8% of incidents
• Electrical Services – 8% of incidents
• Other Industries – 7% of incidents
• Fabricated Metal Products – 7% of incidents
• Equipment Manufacturing – 7% of incidents
• Furniture & Fixtures – 4% of incidents

This information comes to us via the Chemical Safety and Hazard Investigation Board (CSB) Report, and is the closest to OSHA guidelines for classifying combustible dust incidents. Have any questions or comments about these classifications? Let us know by sounding off in the comments section below!