Dust looks harmless, but it poses a potentially explosive hazard in industrial processes. Unlike gases, dust is visible to the naked eye, but its danger lies hidden: in its fine distribution, composition, and the right (or wrong) moment. In this article, we show why not all dust explodes—and how industrial companies can protect themselves from the dangerous types.
🔥 Explosions: Rare, but particularly serious
Although explosions account for only about four percent of all incidents in industrial plants, they cause almost 40 percent of total damage (as of 2020).
Dust explosions caused by highly flammable particles are particularly dangerous. They can endanger human lives, destroy production facilities, and cause long downtimes. This makes a precise safety concept all the more important.
🧼 Cleaning – an often underestimated key to explosion protection
In many companies, fine layers of dust accumulate over time on machines, cable trays, lights, or in ventilation ducts. These deposits appear harmless, but can form explosive mixtures when stirred up—for example, during maintenance or cleaning.
Even 1 mm of dust over a large area can be enough to create a hazardous atmosphere.
That is why it is important to:
- Regular cleaning, even in hard-to-reach places
- No compressed air, but ATEX-certified industrial vacuum cleaners
- Document and monitor cleaning cycles
âť“ Why doesn't all dust explode?
Not all dust is dangerous. The following properties are decisive:
- Flammability: Only flammable substances (e.g., flour, sugar, wood, plastics, metal powders) can explode.
- Particle size: Fine, dry particles (< 500 ÎĽm) are dangerous. Coarse or damp dust is usually not dangerous.
- Concentration: 20–60 g/m³ of air are necessary for a flammable mixture.
- Distribution: Only dust that has been stirred up is explosive – deposits alone are not dangerous.
- Ignition source: No explosion without spark, hot surface, or electrostatic discharge.
Example: Sand is fine, but it is not flammable – there is no risk of explosion.
⚙️ Typical processes with dust explosion risk
- Conveying, grinding, and drying powders
- Filling and emptying silos
- Mixing, packaging, and filling
- Cleaning and maintenance work
Materials at risk:
Grain, flour, sugar, cellulose, aluminum, magnesium, fungicides, medicinal powders, plastics
🚨 Overview of the biggest risk factors
- Flammable concentration: Even small amounts can be dangerous.
- Explosion pressure: Metal or plastic dust can generate pressures exceeding 10 bar.
- Propagation speed: Pressure wave up to 330 m/s (close to the speed of sound).
- Response time: Explosion suppression systems must activate within 75 ms – faster than the blink of an eye.
- Electrostatic discharge: Friction generates voltages of up to 35,000 volts – a small spark is enough.
🛡️ Explosion protection is teamwork
An effective protection concept requires cooperation between plant operators, planners, safety officers, and explosion protection experts.
Important measures:
- Low-dust processes and extraction
- Pressure relief (e.g., bursting discs, flame filters)
- explosion suppression systems
- Grounding and potential equalization
- Regular cleaning and inspection
- ATEX-compliant components and devices