Simply put: Over 70% of industrial dusts are explosive. Any combustible material, when pulverized into fine powder, dispersed in the air at a certain concentration, and exposed to an ignition source, can cause a dust explosion.
Many customers mistakenly believe that “only chemicals can explode.” In fact, many common materials in our daily lives pose explosion risks when in dust form.
1. Common Materials That Cause Dust Explosions
| Category | Common Materials | Description |
| Agriculture/Food | Flour, sugar powder, milk powder, starch, soybean powder, rice bran, coffee powder, tea powder | These are the most easily overlooked dust explosion risks. The 2008 Imperial Sugar explosion in the USA, caused by sugar dust, resulted in 14 deaths and 38 injuries. |
| Wood Products | Sawdust, wood powder, cellulose, paper dust | Fine dust from wood processing has high explosion risk and is classified as St 2 level (strong explosion). |
| Metals | Aluminum powder, magnesium powder, titanium powder, zinc powder, iron powder | These have the strongest explosion power. Aluminum has a Kst value up to 415, magnesium up to 508, classified as St 3 level (very strong explosion). Notably, metals are non-flammable in solid form but become highly explosive as dust. |
| Chemicals/Plastics | Epoxy resin, acrylic powder, polyethylene, polypropylene, sulfur, toner (copier) | Many plastic raw materials are explosive in powder form; toner is also a common explosion source. |
| Coal/Carbon | Activated carbon, charcoal, lignite | Activated carbon has a Kst value of 44, lignite 123 – both are combustible dusts. |
| Fibers | Cotton, synthetic fibers | Cotton dust in textile mills is also a dust explosion risk. |
2. Dust Explosion Classes (Kst Value)
The severity of a dust explosion is measured by the Kst value. The higher the value, the stronger the explosion:
| Explosion Class | Kst Value (bar·m/s) | Explosion Strength | Typical Materials |
| St 0 | 0 | No explosion | Silica sand, silicon dioxide, welding fumes |
| St 1 | 1-200 | Weak explosion | Sugar (35), charcoal (10), milk powder (90), sulfur (151), zinc, wood dust (102) |
| St 2 | 201-300 | Strong explosion | Cellulose, wood powder, polymethyl methacrylate |
| St 3 | >300 | Very strong explosion | Aluminum (415), Magnesium (508), Titanium |
3. Important Safety Concepts
| Concept | Explanation |
| Non-flammable solid ≠ Non-explosive dust | Aluminum, iron, and wood won’t burn in solid form, but as fine powder, their surface area increases dramatically, making them highly explosive. |
| Low Kst value ≠ No risk | Sugar has a low Kst value of 35 (St 1) but still caused severe casualties. Explosion severity relates to dust accumulation – large amounts can still cause disasters. |
| Particle size is critical | Generally, dust with particle size below 425 microns (40 mesh) is considered explosive. The finer the dust, the more dangerous. |
| Only St 0 is safe | Only dust confirmed by professional testing to have a Kst value of 0 is completely free from explosion risk. |
4. What Can USONIC Do for You?
Since your company already has ATEX-certified explosion-proof equipment, this question perfectly leads into your professional value proposition:
“The vast majority of dusts pose explosion risks. The key questions are: Do you know which class your dust belongs to? And, is your dust collection equipment designed to handle it?
USONIC provides:
- ATEX-certified explosion-proof dust collectors, meeting the highest EU safety standards
- Explosion-proof motors, anti-static filter media, and explosion venting panels – triple-layer protection
- Wet dust collectors, using water curtains to capture sparks, naturally explosion-proof
- Water or gas-based fire suppression systems – built-in fire protection for your equipment
If you’re unsure about the explosion risk of your dust, we can help assess it and recommend the most suitable explosion-proof solution.”
In one sentence:
“From flour to aluminum powder, from sawdust to sulfur – wherever there is dust, there is explosion risk. USONIC’s explosion-proof equipment keeps that risk contained.”