How to Identify Combustible Dust Hazards

By Clarion Safety Systems | 28th Oct 2021

In light of OSHA’s recently released top 10 workplace violations list for 2021, we’ll be examining individual hazards and offering our best practice advice to prevent injuries within the workplace. Today’s spotlight is the number 5 violation on OSHA’s list – hazard communication. Related to that, we’ll be honing in specifically on combustible dust hazard identification, communication, and prevention.

Combustible dust incidents can occur in nearly any industry, although they’re most common in agriculture, pharmaceutical production, textiles, chemical manufacturing, fossil fuel generation, metalworking, and recycling operations. It’s critical that employers and employees are educated and knowledgeable of the associated risks and act proactively to mitigate them.

What Causes a Dust Explosion?
Dust explosions are the result of high concentrations of combustible dust particles rapidly combusting inside an enclosed space. When mixed with oxygen, these fine particles can be ignited when coming into contact with a spark, metal ember, cigarette butt, or other ignition source. This quick combustion process is known as deflagration, and results in a high-pressure airwave.

As the airwave explodes out of its enclosed space, it will likely dislodge or stir up combustible dust elsewhere in the area. This will mix the dust with the oxygen in the air, which will make the explosion bigger, and potentially fuel a second dust explosion – or even several more. Some of these may occur inside other machines or containers, as the pressure wave and the fire propagate through the duct system. At this point, the risk of harm to human life, and of destruction of equipment or even entire buildings, is overwhelming.

To break it down, several factors must be present to make the perfect conditions:
1. The dust must be combustible and release enough heat went it burns to sustain a fire.
2. A source of ignition must be in contact with the dust suspension.
3. The dust must be capable of being suspended in the air.
4. The particle size of the dust must be capable of sustaining a flame.
5. The atmosphere needs to contain sufficient oxygen to support and sustain combustion.
6. Confinement or enclosure allows the pressure to build.

What Kind of Materials are Combustible?
Any combustible material can burn rapidly when it’s in a finely divided form. If dust is suspended in air in the right concentration, under certain conditions, it can become explosive. Even materials that don’t burn in larger pieces (such as aluminum or iron), given the proper conditions, can be explosive in dust form. As many industries are at risk for this explosive occurrence, a few examples of additional materials include: food (such as candy, sugar, spice, starch, flour, and feed), tobacco, plastics, wood, paper, pulp, rubber, pesticides, pharmaceuticals, dyes, coal, and metals (such as aluminum, chromium, iron, magnesium, and zinc).

How to Prevent a Combustible Dust Incident in the Workplace
The first step in preventing dust explosions is to identify whether or not you produce, manufacture, or work with any substance that can become a dust. This includes dust producing processes like cutting, grinding, abrasive blasting, polishing, and sieving. Next, training and awareness for all fire and ignition hazards in the workplace is essential, supported by effective labeling and sign systems to communicate safety and instructional information. It’s also important to regularly clean workplace areas where dust has the potential to accumulate over time; this is the best way to prevent combustible dust incidents. Organizations that take good care of their facilities experience fewer fires and explosions and are even more profitable.

The above actions can be paired with providing your company with dust removal systems, conducting regular inspections of confined and unused areas, and supplemental training to ensure that employees are knowledgeable on the risks associated with combustible dust can help to mitigate your company’s risk. The use of surfaces that minimize the amount of dust that can accumulate is also beneficial in reducing your company’s risk of a combustible dust incident. Your final line of defense as a safety professional is making sure that all workers are equipped with properly functioning protective wear, including adequate eye wear, respirators, and the appropriate clothing for the job.

Preventing Explosions Caused by Equipment
Researching the materials used in a workplace is a part of the prevention process, and it’s required for manufacturers to include the possibility of a combustible dust hazard within their safety data sheets (SDS). This can be achieved through conducting a dust hazard analysis, which is required under NFPA 652 for all facilities. This helps identify the stages where your workers are at the greatest risk of a dust explosion.

Regular electrical equipment checks are also important to make sure that everything is working well, that heating systems are stored away from areas where dust could build-up, and that the use of open flame and ignition of any sort is regulated and carefully monitored. The use of misting can also prevent dust from dispersing, which will reduce the probability of spreading out and combusting. Machinery should have covers around the pipes and cables, or should be designed to have the pipes embedded or cables put into the walls. This will help reduce the surface area for dust accumulation. It should also be easy to check if the equipment is bonded and grounded, in an effort to keep static electricity under control.

Your Communication Partner
At Clarion Safety, we understand the importance of hazard communication and prevention, which is why we offer consulting services in order to help mitigate risk and reduce liability for both manufacturers and workplace safety professionals. Our machine risk assessment services help manufactures identify holes in their safety processes, including safeguarding (and we also offer a specific safeguarding audit). At the same time, our custom training services are a great way to get expert assistance on training employers and machinery operators on the safe use of equipment, as well as to better understand the supporting signage and labels that communicate key information. Reach out to our team today if you have any questions about labels, signs, or consulting services.