When it comes to fire risk assessment, there is one thing that is hard to spot, that can be all around you, and can cause fires. That is combustible dust.
In 2008 there was a huge explosion at a sugar refinery in near Savannah, Georgia in the USA. There were 14 deaths and 36 injuries. A massive accumulation of combustible sugar dust throughout the building fuelled the explosion.
Dust, therefore, can be deadly, and is regarded as a major potential fire hazard.
Types of Combustible Dust
Organic or inorganic dust particles, finely ground, and airborne can be hazardous when exposed to an oxidising agent.
It might surprise you how many combustible dusts there are. They include foods, plastics, metals, woods and coal. Predicting how hazardous they are can prove difficult as this also depends on the concentration of the dust and the size of its particles.
There is, however, an explosion indices test for combustible dust, based on Kst values. The higher the Kst value, the more dangerous the dust. This is essential for measuring dust concentrations and ensuring a thorough investigation of their explosive properties.
Explosion testing based on these values can be applied to a range of combustible dusts, including grain and coal dust, aluminium dust, sugar, flour and even sewage sludge.
Various workplaces and industries are at risk from dust explosions, including food production, chemical manufacturing, woodworking and recycling facilities, metal processing plants and coal-fired power plants.
The transporting, handling and processing of materials causes dust to accumulate, and virtually any workplace can be at risk.
Normally the three crucial elements for a fire are: a fuel to burn; oxygen; and some sort of igniting element, such as a spark, or heat source. For a dust explosion two more elements come into play: dispersion of the right concentration of dust particles; and confinement of this dust cloud.
Dispersion lets the particles into the air, while confinement ensures they stay in enough of a concentration to be combustible.
Deflagration is what happens when these particles explode into flame.
Preventing Flash Fire Hazards
Ensuring that flash fires from dust explosions do not occur, requires the right procedures and training.
This means having dust collection systems in place; minimising how much dust escapes from equipment; cleaning surfaces that accumulate dust frequently and systematically; regular inspections; and thorough training of employees.
It’s also vital to look at potential ignition sources, such as electrical equipment and wiring, static electricity, open flames and sparks, and mechanical friction.
Dust can be a danger to your workforce and your workplace. For more about this and other aspects of fire risk assessment, contact Comply at Work. We’re here to offer you expert advice and support.