Combustible Dust Explosions: Why They Happen (And How to Reduce Your Risk)
A dust cloud explosion is a risk your workplace simply must mitigate for two unmissable reasons: the potentially lethal nature of the knock-on effects and because a serious explosion involving a seemly harmless substance can easily occur. After all, one explosion – a 1981 blast at a plant in Banbury, England – involved custard powder […]
A dust cloud explosion is a risk your workplace simply must mitigate for two unmissable reasons: the potentially lethal nature of the knock-on effects and because a serious explosion involving a seemly harmless substance can easily occur.
After all, one explosion – a 1981 blast at a plant in Banbury, England – involved custard powder (yes, custard powder!) igniting as a dust cloud within a building. Nine people were injured and substantial damage was caused.
Very often, too, a secondary explosion occurs. Meaning combustible dust cloud risks are a danger no one should take for granted.
Read on to discover the ‘why’ of dust cloud explosions, an overview of safety advice plus tips for specifying equipment for safer working.
Combustible Dust Explosions: The ‘Perfect Storm’
The best way to understand why a dust cloud ignites so dramatically is to think about why a pile of materials burns slowly: the amount of surface area exposed to oxygen in the air.
Add an ignition source, fine enough dust, confinement and movement to create a cloud and the ‘formula’ for an explosion can suddenly occur.
The result? A fireball, secondary explosions, serious damage and potentially injury or worse.
The FM Global video shown here – along with the excellent advice that “if it didn’t start out as a rock, it can explode!” – demonstrates the result of just one hard hat worth (5kg) of coal dust being ignited after a charge was used to disturb and suspend the dust.
The list of just some of the materials that become a combustible dust, compiled by CCOHS in Canada, are surprising:
- 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.
A US OSHA poster showing even more examples is also available.
What happens when it goes wrong? And how easily can it go wrong?
In example, the Hoeganaes Corp. metal powder plant outside Nashville USA in early 2011, the jolt of a machine restarting was enough to knock a fine iron dust into the air. The dust was thought to have been ignited by the spark from an exposed wire.
The injuries to an operative working nearby were, sadly, fatal.
Clearly, the ability of a combustible dust explosion to occur in seemingly innocuous circumstances means taking steps to prevent injury or death are nothing short of essential.
Combustible Dust Explosions: Reducing Risk
The UK HSE’s publication Safe Handling of Combustible Dusts recommends starting, of course, by assessing the risk: “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?”
The guidance document goes on to recommend three options for mitigation:
- 1, Eliminating the risk
- 2, Providing controls to minimise the risk
- 3, Providing supplementary controls to mitigate the consequences.
Further details are available from the HSE document, however careful choice of equipment can both remove risk (for example, by ensuring the equipment is designed to avoid causing an ignition) and require less time on-site thanks to efficiency and ease of use features.
Our final section below lists recommended equipment for areas where a risk of a combustible cloud exists. Need help choosing? Simply tell us about your project. We’ll be proud to help.
Combustible Dust Explosions: Equipment for Safer Working
Right now portable SA Equip products designed to perform in dust hazard environments with extreme reliability and safety are in use across the globe.
Products with Zone 21/22 hazardous dust environment certification include:
• SA LUMIN EX LED Vessel Entry Kits: A highly reliable system for confined space, vessel or tank work, the kit’s transformer powers four work area lights with exceptional safety.
• SA LUMIN EX LED Tower Light: Rugged, fully transportable and up to 5 metres height, The SA LUMIN LED Tower Light can be moved by a simple operator in minutes and is incredibly stable.
• SA POWERNET EX 400va Transformer: This portable and extremely durable unit is ideal for powering temporary lighting as well as other small equipment. Superbly reliable, even in extreme conditions.
And many more.
But why choose SA Equip? Simply because SA Equip already helps clients across the world to achieve optimal lighting, heat and ventilation results in challenging environments. An in-house product development team can even devise a bespoke solution.
Most of all, SA Equip brings almost 100 years of pacesetting service and knowledge – with a foundation in the most extreme shipping and oil industry environments – to customers across heavy industry, aerospace, defence, utilities, pharmaceuticals, distilling, power stations and more.
Simply speak to a member of the SA Equip team for help with choosing the right equipment.
(Note: nothing stated in this article is intended as, or should be considered to be, formal safety advice. Please conduct the correct legislative and policy research for your project).