Published April 1, 2024 Authored by Dr. Chris Cloney and Jon Barrett of Dust Safety Science
A picture of a Combustible Dust Explosion and Combustible Dust, in a Food Processing Facility, on a Conveyor Belt
Key Takeaways:
- Industry Dynamics: The food processing industry, encompassing various operations such as milling, grinding, drying, and packaging, handles a wide range of organic materials that can generate combustible dust. This industry sector faces unique challenges due to the diverse nature of food products and dry goods processed, including grains, sugars, spices, and powdered additives. The handling and processing of these materials create conditions conducive to the accumulation of combustible dust, presenting significant hazards if not managed properly.
- Hazards of Combustible Dust: Combustible dust in the food processing industry poses serious risks due to its potential for explosion or fire. Fine particles generated during food processing operations can become suspended in the air, forming explosive mixtures when combined with oxygen. Ignition sources such as sparks, static electricity, hot surfaces, or open flames can trigger rapid combustion, leading to devastating explosions that endanger workers, damage equipment, and disrupt operations.
- Specific Concerns: Food processing facilities often handle bulk quantities of ingredients and dry goods, such as flour, sugar, starch, and spices, which are prone to generating combustible dust. Operations involving milling, grinding, mixing, and blending can produce fine particles that accumulate on surfaces, inside ventilation systems, and on structural components and equipment, increasing the risk of dust explosions. Drying and dehydration processes are common in the food industry for preserving perishable products or creating powdered ingredients. However, these processes release significant amounts of dust, especially when conducted at high temperatures.
The Specific Food Processing Equipment, Combustible Dust Generation, and Root Causes
In food processing facilities, common sources of combustible dust include flour, sugar, cocoa powder, and various other food powders and particles. The Occupational Safety and Health Administration, (OSHA), identifies Food Ingredients as Combustible Dust. Fine particles generated during various stages of food processing, such as grinding, pulverizing, blending, and mixing, constitute the primary source of combustible dust in these facilities. Combustible dust is considered to be a solid material that is composed of distinct particles, regardless of their shape, size, or chemical composition. The production of food requires the transportation, storage, and processing of a wide range of raw ingredients. The food processing industry is vital for delivering safe and consumable products to our tables.
However, beneath the surface of this seemingly innocuous sector lies a hidden threat – combustible dust. The hazards posed by combustible dust in food processing facilities have been a cause for concern, leading to numerous incidents that demand our attention and analysis. Combustible dust is an ever-present danger in various industries, including food processing. It consists of fine particles that, when suspended in the air in the right concentration, can ignite and cause explosions or fires. Common food processing materials like flour, sugar, spices, and starches can become combustible when dispersed in the atmosphere under certain conditions, such as inadequate ventilation or improper housekeeping.
Combustible dust is a serious workplace hazard that can lead to catastrophic incidents if not properly managed. To mitigate the risks associated with combustible dust, various standards and regulations have been put in place. In the year 1923, was when the NFPA published the first standard on combustible dust, as no national regulations were enacted to address the problem of combustible dust directly, and dust-related explosions and fires, along with loss of life and property, continued to occur. Listed are the important combustible dust standards and regulations, and why they are crucial for the safety of workers and the prevention of industrial disasters:
- NFPA 61, Standard for the Prevention of Fires and Dust Explosions in Agricultural and Food Processing Facilities NFPA 61 protects lives and property from fires and dust explosions in facilities handling, processing, or storing bulk agricultural materials, their by-products, or other agricultural-related dust and materials.
- NFPA 68, Standard on Explosion Protection by Deflagration Venting applies to the design, location, installation, maintenance, and use of devices and systems that vent the combustion gases and pressures resulting from a deflagration within an enclosure so that structural and mechanical damage is minimized. Chapter 8 of the NFPA 68 provides guidance on Venting of Deflagrations of Dusts and Hybrid Mixtures, Effects of Vent Ducts, Bins, Hoppers, and Silos, Venting of Dust Collectors Using Bags, Filters, or Cartridges, Bucket Elevators, Venting Internal to Building with Flame-Arresting and Particulate Retention Device, Venting Silos or Other Storage Vessel Provided with Integral Bin Vents, and Deflagration Venting of Enclosures Interconnected with Pipelines.
- NFPA 654 Standard for the Prevention of Fire and Dust Explosions from the Manufacturing, Processing, and Handling of Combustible Particulate Solids. The NFPA 654 Standard is referenced by OSHA’s Combustible Dust National Emphasis Program (NEP) to identify dust hazards and define mitigation strategies that help protect life and property. The standard provides industry-recognized safety practices for facility and systems design, process equipment protection, fugitive dust control and housekeeping, ignition source identification and control, fire protection, training and procedures, inspection, and maintenance. Annexes offer guidance on the application of area electrical classification for various dust accumulation levels.
The hazards associated with combustible dust are not to be underestimated. When ignited, the explosive potential of these particles can wreak havoc, leading to devastating consequences for both human lives and property. In the realm of food processing, seemingly harmless substances—sugar, flour, spices, starch, and even dried milk or grain particles—have the potential to form combustible dust. Here is a list of common processing equipment often found in food processing facilities that can be associated with combustible dust:
Grinders and Pulverizers: Used for reducing food ingredients into fine particles, these machines can generate dust from substances like spices, grains, or nuts.
Mixers and Blenders: Equipment utilized to blend different ingredients can create dust, especially when handling powdered substances like flour or powdered flavorings.
Dryers and Evaporators: These appliances are used to remove moisture from food products, and during this process, they can generate dust from dried food materials.
Conveyors and Elevators: Transport systems used in food processing plants may agitate or transport fine particles, leading to dust dispersion.
Packaging Equipment: Machinery involved in packaging powdered food products can also contribute to dust accumulation.
Milling and Sifting Machines: These machines can generate dust when refining or separating food materials like grains or sugar.
Comprehensive risk management in food processing facilities involves understanding the equipment and processes contributing to combustible dust hazards. Implementing a combination of preventive measures, stringent protocols, and ongoing vigilance can significantly mitigate the risks associated with combustible dust and ensure a safer working environment for all involved.
Examples of Specific Foods and Ingredients, Creating Combustible Dust Generation
Combustible dust is a significant hazard in various industries, particularly in food processing and manufacturing. Understanding the generation and impact of combustible dust from specific food and ingredient types is crucial for ensuring workplace safety and preventing potential accidents. Here are some food and ingredient types that contribute to examples of combustible dust generation:
Almond Dust, Animal Feed Processing, Barley Dust, Chile Dust, Cocoa Dust, Coffee Dust, Dehydrated Alfalfa, Dried Egg Yolk, Dried Herbs, Dried Rice, Fish Meal, Flour Dust, Grain Dust, Ground-Up Pet Food, Malt Dust, Milk Powder, Nut Dust, Overdried Pulp, Peanut Dust, Potato Dust, Powdered Milk, Rice Dust, and Sugar Dust.
Understanding the specific food and ingredient types that contribute to combustible dust generation is crucial for implementing effective preventive measures, including proper ventilation, dust collection systems, housekeeping protocols, and employee training on safety practices. Mitigating the risks associated with combustible dust is vital to ensure a safe working environment in food processing and manufacturing industries.
A picture of a detailed analysis and percentages of several Industries, including Food Processing, affected by Combustible Dust, from Dust Safety Science
Historic Food Processing Industry-Related Combustible Dust Explosions
Combustible dust incidents, continue to occur worldwide and in the Food Processing industry, as presented in this combustible dust research and incident database from Dust Safety Science. In addition, statistics of the most prevalent industries, regarding combustible dust incidents, are also captured in this Annual Incident Report Database, from Dust Safety Science. During 2022, Food Processing dust occurred in 9.4% of combustible dust incidents. In addition, the Dust Safety Science Podcast educates the public on Reconciling Hygiene with Explosion Safety in Food Industries with Dr. Chris Bloore. Some of the historic Food Processing Industry combustible dust explosions and incidents include:
- Giacomelli’s Bakery Warehouse (1795): According to ScienceDirect, the 1st recorded combustible dust explosion, occurred at an Italian flour mill, when flour dust came in contact with a mounted lamp, which injured two workers. A local man named Count Morozzo examined the results of the explosion and wrote a report giving the probable cause of the explosion as the dry flour dust. Source: Dust explosion causation, prevention and mitigation: An overview
- The Douglas Starch Works Plant Explosion of 1919: The Douglas Starch Works company produced cooking starch and oil, laundry starch, soap, and animal feed. A massive explosion rocked the building, which was located on First Street SW, just off of C Street SW. The walls collapsed, pieces of the factory were hurled up to two miles away, and smoke billowed in the evening sky. Joseph Hubbell, manager of the National Inspection Company of Chicago, commented on the disaster in an issue of the National Underwriter. It was his opinion that the explosion occurred in the plant’s wet process buildings, where some dry starch may have built up. Source: The History of Douglas & Company
- The Imperial Sugar Refinery Explosion (2008): In February 2008, the Imperial Sugar Refinery in Port Wentworth, Georgia, suffered a massive explosion triggered by combustible sugar dust. The explosion claimed the lives of 14 workers and injured dozens more. The refinery was heavily damaged, and nearby communities were affected by the blast. Investigations revealed inadequate housekeeping practices and a lack of proper dust explosion prevention measures. This incident prompted regulatory changes and increased awareness of the dangers of combustible dust in industrial settings.
The history of combustible dust explosions in the food processing industry spans centuries, with incidents ranging from the earliest recorded explosion at Giacomelli’s Bakery Warehouse in 1795 to more recent tragedies like the Imperial Sugar Refinery Explosion of 2008. These incidents, separated by time but linked by a common thread of neglecting safety measures, underscore the inherent risks associated with the accumulation of combustible dust in industrial settings. Giacomelli’s Bakery Warehouse marked the inaugural entry in the annals of combustible dust explosions, as flour dust ignited upon contact with a mounted lamp, injuring workers and illuminating the hazards posed by seemingly innocuous materials. Subsequent events, such as the Douglas Starch Works Plant Explosion of 1919, further underscored the catastrophic consequences of inadequate safety protocols, emphasizing the importance of proper ventilation, housekeeping, and ignition source control to mitigate the risk of explosions.
A picture of the NFPA 61 Guide and the NFPA 61 Standard for the Prevention of Fires and Dust Explosions in Agricultural and Food Processing Facilities
Conclusion
Despite advancements in safety regulations and technology, incidents of combustible dust explosions persist, as evidenced by the ongoing documentation provided by Dust Safety Science’s combustible dust research and incident database. This comprehensive resource not only catalogues past tragedies but also sheds light on the prevalence of such incidents in various industries. According to Dust Safety Science’s Annual Incident Report Database, food processing dust accounted for 9.4% of combustible dust incidents in 2022, underscoring the continued need for proactive measures to address combustible dust hazards within the food processing sector and beyond.
In light of the statistics and historical context, it is evident that combating combustible dust hazards requires a multifaceted approach that prioritizes ongoing education, rigorous safety protocols, and industry-wide collaboration. The lessons gleaned from past tragedies, such as the Giacomelli’s Bakery Warehouse explosion in 1795 and the Imperial Sugar Refinery explosion in 2008, underscore the importance of vigilance and adherence to safety standards. By leveraging resources like Dust Safety Science’s databases, stakeholders in the food processing industry and beyond can gain valuable insights into risk factors, trends, and best practices for mitigating combustible dust hazards.
About Dust Safety Science
For more from Dr. Chris Cloney on Combustible Dust in the Food Processing Industry, visit this podcast episode: Reconciling Hygiene with Explosion Safety in Food Industries with Dr. Chris Bloore.
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