What Are Dust Explosions

The first blog on our dust explosion series focuses on explosive dusts and dust explosions. We will be discussing the science behind dust explosions aiming to provide a good understanding of the nature of dust explosions that may occur on your site.

Why should we be concerned about the suspended dust in our facilities?

Several industries are known to have dust suspension and carry the risk of dust explosion. Food processing industries, woodworking facilities, metalworking processes, pharmaceutical manufacturing facilities are some of the examples of industries where dust accumulation can potentially lead to a dust explosion. These industries play an important role in human life by supplying essential goods and materials such as food products, construction materials, medications, and chemical substances. Therefore, protecting these industries against explosions is imperative. The rapid combustion of combustible dust generates a shockwave that can disperse additional dust particles, leading to secondary explosions and fires. The force of the explosion can rupture equipment, damage structures, and propel debris at high velocities, posing significant risks to personnel and property within the vicinity. Numerous instances of dust explosions have been reported over time resulting in loss of life and injuries.

What is powder or dust explosion?

Dust explosions are caused by a combination of several factors that create an explosive atmosphere within an area. Understanding these factors is crucial for preventing and mitigating the risks associated with dust explosions.

A dust explosion occurs when fine particles suspended in the air within an enclosed space rapidly combust if the ignition energy is sufficiently high. These explosions can happen where any dispersed powdered combustible material is present in high-enough concentrations if the particle size is particularly small to form a combustible mixture. These particles can originate from various materials commonly found in industrial processes, including wood, coal, grain, milk powder, sugar, metal, plastic, and chemicals. When these materials are processed, handled, or transported, they can generate fine dust particles that become suspended in the air. Processes such as milling, grinding, cutting, crushing, and conveying can create airborne dust clouds. Additionally, dust accumulations on surfaces or in equipment can become disturbed, leading to the dispersal of dust particles into the air. Unlike flammable vapors and gases, most dusts (both hazardous and non-hazardous) with a particle size between 0.02 and 0.4mm are considered to be combustible.

Also, dust explosions require an ignition source to initiate the combustion process. Common sources of ignition include sparks, flames, hot surfaces, electrical equipment, friction, and static electricity. Ignition sources can arise from various sources within industrial processes, such as equipment malfunction, hot work operations, mechanical failure, or human error.

The confinement of combustible dust within an enclosed or semi-enclosed space can increase the intensity of a dust explosion. When dust particles are dispersed in a confined area, the rapid combustion generates pressure that builds up within the enclosure, leading to a powerful explosion. The confinement of dust explosions can occur in equipment such as dust collectors, silos, ductwork, pipelines, or processing vessels.

Is it possible to prevent dust explosion and ensure explosion safety?

Preventing dust explosions requires implementing a thorough ATEX risk assessment which involves hazard assessment, dust characteristics, ignition sources risk assessment, technical and organizational control measures, etc. The first step is to identify whether the dust is combustible which can be confirmed by laboratory tests to ISO/IEC 80079-20-2. To assess ignition sources, it is essential to evaluate the characteristics of the materials involved. This includes determining factors like particle size, moisture content, minimum ignition temperatures for both cloud and layer formations, and electrical resistivity.

Customized control measures must be tailored to each site to ensure explosion safety. This may include choosing suitable equipment for hazardous areas, establishing minimum ventilation requirement, mitigating ignition sources, and installing explosion venting or suppression systems. These technical control measures should be carefully detailed in the ATEX risk assessment. Organizational control measures such as permit to work system, emergency planning and housekeeping should also be incorporated into the ATEX risk assessment for comprehensive safety management. Overall, control measures are necessary to be reviewed to prevent and mitigate the hazards associated with combustible dust and reduce the likelihood of dust explosions occurring. Without adequate control measures in place, the risk of dust explosions can pose significant dangers to personnel, property, and the environment.

Occupli Consultancy specialists provide practical solutions and advice to all our clients in all areas of ATEX related services. Our team work to legislative requirements and benchmark against industry best practice to produces assessments for our clients. Occupli Consultants have carried out ATEX risk assessments in a range of different industries which include the medical devices, pharmaceutical, agricultural, manufacturing and many more.

If you require ATEX services, reach out to our team of consultants here.