Why Combustible Dust Explosions Happen and How to Reduce Your Risk

A dust explosion is a workplace hazard that must not be overlooked, for two critical reasons. Firstly, the consequences can be devastating, both in terms of human safety and structural damage. Secondly, these explosions can be triggered by substances that seem harmless under normal conditions.

In 1981, a powder explosion at a plant in Banbury, England, was triggered by custard powder, a seemingly harmless substance. The dust cloud ignited, causing nine injuries and significant structural damage.

What makes dust cloud explosions particularly dangerous is the frequent occurrence of secondary explosions, which are often more destructive than the initial event. This is why combustible dust risks should never be underestimated.

In this article, we’ll explore the causes of dust cloud explosions, share key safety recommendations, and offer guidance on specifying the right equipment to ensure safer operations in potentially explosive environments.

What is Combustible Dust?

The key to understanding why dust clouds ignite so violently lies in comparing them to a solid pile of the same material. A compact pile burns slowly because only a limited surface area is exposed to oxygen. But when that same material is dispersed into a fine dust cloud, its surface area increases dramatically, making it far more reactive.

Introduce an ignition source, sufficient dust concentration, confinement, and some air movement to keep the dust suspended, and you’ve created the ‘Perfect Storm’ for an explosion.

The result can be catastrophic: a fireball, secondary explosions, significant structural damage, and, tragically, the potential for serious injury or loss of life.

The FM Global video shown here powerfully demonstrates the explosive potential of dust. Backed by the memorable advice, “if it didn’t start out as a rock, it can explode!”, the video shows how just one hard hat’s worth (around 5 kg) of coal dust, once disturbed and suspended by a charge, can ignite with devastating force.

The Canadian Centre for Occupational Health and Safety (CCOHS) has compiled a list of materials that can become combustible dusts, and many of them are surprisingly common:

  • Agricultural products such as egg whites, powdered milk, cornstarch, sugar, flour, grain, potato, rice, etc.
  • Metals such as aluminium, bronze, magnesium, zinc, etc.
  • Chemical dusts such as coal, sulphur, etc.
  • Pharmaceuticals
  • Pesticides
  • Rubber
  • Wood
  • Textiles
  • Plastics

A poster from the Occupational Safety and Health Administration (OSHA) in the United States also highlights a wide range of materials capable of becoming combustible dusts, many of which may surprise you.

So, what happens when things go wrong, and just how easily can they go wrong?

One powerful example comes from the Hoeganaes Corporation metal powder plant near Nashville, Tennessee, in early 2011. There, the simple jolt from a machine restarting was enough to dislodge fine iron dust into the air. It’s believed that a spark from an exposed wire then ignited the suspended dust. Tragically, a nearby worker sustained fatal injuries.

This incident underscores a critical point: combustible dust explosions can occur under seemingly routine conditions. That’s why taking proactive steps to prevent ignition, control dust, and protect workers isn’t just good practice – it’s absolutely essential.

How to Reduce the Risk of Combustible Dust Explosions

The UK Health and Safety Executive (HSE), in its publication Safe Handling of Combustible Dusts, rightly emphasises that the first step in managing combustible dust risks is a thorough risk assessment. As the guidance notes:

“This task should be your starting point, and it can be addressed under a series of questions. Is my dust capable of exploding? Where could dense dust clouds form? What could ignite them? How likely is this? What would be the consequences? Who would be at risk? Can we prevent the risk of an explosion altogether? If this is not possible, what can be done to protect people, and minimise the consequences of an explosion?”

Following this, the HSE outlines a three-tiered approach to mitigation:

  • Eliminate the risk where possible
  • Introduce controls to minimise the risk
  • Implement supplementary controls to reduce the consequences of an explosion

While full details are available in the HSE document, one key takeaway is that selecting the right equipment plays a vital role. Properly designed equipment can significantly reduce ignition risks and, in many cases, eliminate them altogether. Additionally, well-specified tools often lead to greater on-site efficiency, requiring less time and effort due to user-friendly features and safe, compliant design.

Equipment for Safer Working in Dust Hazard Environments

SA Equip’s portable products are engineered for maximum reliability and safety in dust hazard environments, and are trusted by industries around the world. Certified for use in Zone 21 and Zone 22 hazardous dust environments, these solutions deliver dependable performance in the most demanding conditions.

Key certified products include:

  • SA LUMIN EX LED Vessel Entry Kits: A safe, reliable for confined space work in vessels or tanks, with a robust transformer powering four high-performance lights.
  • SA LUMIN EX LED Tower Light: A rugged, 5-metre-high portable tower light that sets up in minutes and ideal for temporary lighting in hazardous dust zones.
  • SA POWERNET EX 400VA Transformer: Durable and portable, this compact transformer reliably powers temporary lighting and small tools in dust-prone environments.

SA Equip helps clients worldwide achieve optimal lighting, heating, and ventilation results in challenging environments. Our in-house product development team is also ready to create bespoke solutions tailored to your needs.

With a foundation in some of the most extreme shipping and oil industry environments, SA Equip brings decades of expertise and service to a wide range of sectors, including heavy industry, aerospace, defence, utilities, pharmaceuticals, distilling and power stations.

Simply speak to a member of the SA Equip team for guidance in selecting the right equipment.

Please note: Nothing in this article is intended to serve as formal safety advice. We recommend conducting thorough legislative and policy research specific to your project to ensure compliance with relevant regulations.

Please also see the following blogs:
The Importance of ATEX Plugs, Sockets and Couplers
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