Combustible Dust in the Work Place

When your work application produces potentially dangerous by-products, it’s necessary to find safe and efficient solutions that remove these risks from the equation and allow work to carry on unabated. One by-product of many processes that is particularly dangerous is combustible dust. The Dangerous Substances and Explosive Atmospheres Regulations require employers to make an assessment of the risks arising from dangerous substances, and this specifically includes dust which can explode. Explosive dust is not a new phenomenon and well over 100 years of incident records exist that have accumulated in a large loss of life and substantial property damage

What is Combustible Dust?

Combustible dust refers to metallic or non-metallic airborne dust that is capable of causing an explosion in your work space. The determining factor on whether or not industrial dust is combustible lies in its KST value, which measures how explosive dust is when compared to other types of dust. Any reading higher than zero indicates the risk for explosion. Although a cloud of flammable dust in the air may explode violently, not all mixtures will do so. The concentration of dust and air must be within the upper and lower explosive limits for the dust involved. The most violent explosions usually result from dust/ air mixtures that are fuel rich. This means that the oxygen available in the air cannot burn all the dust, creating partly burnt, glowing particles or embers that remain after the explosion. These embers in turn can reignite additional dust clouds – such as those shaken loose from the force of the initial explosion – and if enough air is available. These multiple explosions often result in catastrophic damage and loss of life

Why Does Dust Explode?

A dust explosion involves the rapid combustion of dust particles that releases energy and usually generates gaseous reaction products. A mass of solid combustible material as a heap or pile will burn relatively slowly owing to the limited surface area exposed to the oxygen of the air. Example In 1981 an explosion and a plant in Banbury which manufactured custard powder injured nine men and caused significant damage to an external wall of the building – risking collapse. A fault in the pneumatic conveying system caused a holding bin to overfill and the air pressure in the bin to fail. The released custard powder ignited as a dust cloud. High Risk Applications:

  • Metalwork (aluminium, magnesium, or titanium and others) – cutting, grinding, or finishing

  • Ceramics – raw product handling and enamel spray

  • Chemicals – material handling, crushing, grinding, roasters, kilns, and coolers

  • Coal mining – material handling, de-dusting, drying, air cleaning

  • Food (flour, sugar, and others) – mixing, grinding, blending, bagging, and packaging

  • Foundry – sand handling, tumbling mills, abrasive cleaning, and shakeout

  • Pharmaceutical – mixing, grinding, blending, bagging, and packaging

  • Rubber – mixing, grinding, talc dusting, de-dusting, and batch-out rolls

  • Woodwork – woodworking machines, sanding, waste conveying


Dangers of Combustible Dust

Work applications that have the capacity to produce combustible dust create some of the most hazardous work conditions imaginable if the dust is not contained and removed safely. Consequences of a serious combustible dust incident include

  • Serious injury or death to nearby workers

  • Severe property damage

  • Irreversible environmental damage

  • Long-term business interruption

  • High Risk Industries and Applications


The possibilities lead toward the catastrophic, and many companies are unaware that they have a combustible dust issue, or where in their work space this dangerous dust is settling. According to the UK Health and Safety Executive, combustible dust may be a by-product of processing or handling. Such dusts can include but are not limited to:

  • Agricultural products like powdered milk, sugar or flour

  • Agricultural dust from cocoa beans, carrots, rice flour and tomato

  • Carbonaceous dusts like activated charcoal, lignite and cellulose

  • Chemical dusts like dextrose, lead stearate and sulphur

  • Metal dusts like aluminium, magnesium and zinc

  • Plastic dusts like polyethylene, acrylamide and phenolic resin


Example

An explosion initiated in the dust collector of a grain storage facility at Blaye in France. The towers contained elevators and the gallery over the 44 silos contained belt conveyors. All the areas were open allowing the spread of the dust clouds and flames. Both towers, the entire gallery and 28 silos were lost…. Along with 11 lives. Dependable Combustible Dust Solutions. At Vodex, we provide high quality, safe solutions to remove combustible dust that meet all required regulatory guidelines. Whether it is a wet-filtered downdraft table or a wet dust collector, the experts at Vodex have you covered for every work application. Don’t let combustible dust lead to disastrous results for your workers or your business. Call for a customized solution today on 01489 899070 or email sales@vodex.co.uk Vodex Ltd are ATEX directive trained and ready to help you with your dust control requirements. For further information please see Control of Substances Hazardous to Health 2002 Amended, Dangerous Substances and Explosive Atmosphere Regulations, Safe Handling of Combustible Dusts: Precautions against explosions HSG103.References: Safe Handling of Combustible Dusts: Precautions against explosions HSG103. The American Occupational Health and Safety Administration.