Describes combustible dust, methods to control combustible dust, and includes descriptions of vacuum cleaners for combustible dust
You will learn:
Combustible dust consists of solid material made up of particles with varying sizes, forms, and chemical properties that can ignite and lead to fires or rapid explosions. These explosions swiftly propagate through an area, causing severe fires, devastation, and significant risks to human safety. The primary threat arises when the dust is extremely fine—less than 425 micrometers (μ)—and becomes airborne.
Combustible dust particles typically originate from materials used in industries such as manufacturing, agriculture, and chemicals. To qualify as combustible, dust must possess traits that make it prone to ignition and subsequent combustion when airborne. Several factors determine its flammability, including particle size, concentration, and chemical composition.
Recent explosions involving combustible dust, coupled with concerns from the Occupational Safety and Health Administration (OSHA), have led more businesses to assess potential combustible dust hazards in their facilities. Manufacturing operations dealing with any dust forms are increasingly aware of the associated risks. Furthermore, the National Fire Protection Association (NFPA) provides a definition, under provision 654 (2013 edition), of combustible dust as:
“A finely divided combustible particulate solid that presents a flash fire hazard or explosion hazard when suspended in air or the process-specific oxidizing medium over a range of concentrations.”
Understanding the different types of combustible dust is crucial for maintaining industrial safety and implementing effective dust explosion prevention measures. As everyone knows, there are specific parameters that have to be present for a fire to occur. Referred to as the fire triangle, the three essential components necessary to initiate a fire are fuel, oxygen, and an ignition source. In the case of dust explosions—a key occupational hazard in many industries—two additional elements are required: dispersion and confinement. The addition of these two extra parameters expands the fire triangle into what is known as the dust explosion pentagon.
The primary danger associated with a dust explosion lies in the confinement of the dust cloud—a situation in which the concentration of combustible material provides the critical mass for ignition. When a dust cloud is dispersed, deflagration occurs, causing an unconfined flash fire which, while hazardous, may be less catastrophic than a fully confined explosion. At the heart of every dust explosion event is the combustible material itself—ranging from organic dusts to metallic or plastic dust—each with unique properties and industrial safety challenges. Recognizing potential fuel sources and managing their concentration and dispersion is fundamental to dust hazard analysis (DHA) and compliance with safety standards such as NFPA 652.
To effectively manage the risks posed by combustible dust hazards, industries rely on a scientific classification process that standardizes the evaluation of dust explosibility and potential hazards. This process, mandated and guided by regulatory bodies (such as OSHA and the National Fire Protection Association), enables companies to develop appropriate dust control and explosion mitigation strategies. By studying and understanding the characteristics of various types of dust—including wood, sugar, flour, metal, coal, rubber, and plastic—companies can identify conditions that might lead to a dust deflagration or secondary explosions and put in place measures for fire and explosion risk reduction.
The regulation and ongoing monitoring of dust ignition hazards utilize dust classifications to guide work sites in adhering to industry-specific dust safety protocols. Combustible dust is divided into classes—St 0, St 1, St 2, and St 3—each denoting the dust’s deflagration index (Kst) and its explosive potential. Knowing the Kst value of a material is paramount for determining the appropriate use of dust collectors, explosion vents, suppression systems, and other critical engineering controls.
Kst: Size-normalized maximum rate of pressure rise under standard testing conditions, used to quantify the explosibility of dust clouds.
| Combustible Dust Classifications Table | ||
|---|---|---|
| Explosion | KSt Value | Characteristics |
| ST 0 | KSt = 0 | No Explosion |
| ST 1 | KSt > 0 and ≤ 200 (bar-m/s) | Weak Explosion |
| ST 2 | KSt > 200 and ≤ 300 (bar-m/s) | Strong Explosion |
| ST 3 | KSt > 300 (bar-m/s) | Very Strong Explosion |
Additional Factors in Dust Hazard Classification: Particle size, dust cloud concentration, moisture content, minimum ignition energy (MIE), minimum explosive concentration (MEC), and environmental conditions such as temperature and humidity all play significant roles in dust combustibility and explosion severity.
Employers are required to conduct a and maintain comprehensive housekeeping, proper ventilation, and to reduce the risk of dust-related industrial accidents.
Sugar is an organic substance highly susceptible to combustion, forming an explosive dust hazard in food processing facilities. Fine particles of sugar dust, especially when airborne in confined processing areas, can rapidly ignite, causing severe secondary explosions that may result in catastrophic facility damage. Sugar dust explosions have been the cause of multiple high-profile industrial accidents in processing plants due to improper dust management and insufficient dust extraction systems. Refineries generate significant sugar dust during the last stages of refining, particularly when sugar crystals move through dryers and are transferred to silos or packaging areas. Grinding to create confectionery powder further increases dust generation. Sugar dusts typically have a standard particle diameter of 420 ÎĽm or smaller, placing them firmly within the range of concern for fire and explosion risk assessment.
Industries at risk: Sugar refineries, bakeries, cereal production, candy manufacturing, and beverage processing plants must implement stringent controls and continuous dust monitoring to prevent sugar dust accumulation and ignition.
Wood dust is generated during milling, cutting, sanding, and finishing operations commonly found in sawmills, furniture production facilities, and carpentry workshops. All forms of wood dust, especially fine particulates, are combustible and can present significant explosion hazards if not properly controlled. The volatility of wood dust makes it especially dangerous, as its fine particles are easily dispersed and can rapidly form explosive concentrations in the air. Primary wood dust explosions can trigger devastating secondary explosions by dispersing additional dust during the initial blast, greatly magnifying the destructive potential within a facility. As in all combustible dust scenarios, implementing local exhaust ventilation, HEPA filtration, and regular surface cleaning are critical for fire risk mitigation.
Worker Protection: Proper use of personal protective equipment (PPE), dust masks or respirators, and explosion-proof electrical systems is vital for personnel safety in woodworking environments prone to dust ignition.
Flour dust is a significant fire and explosion risk within food processing and bakery facilities. These environments often involve bulk transfers, mechanical mixing, pneumatic conveying, and storage systems, all of which can resuspend combustible flour dust. Dust explosions may occur when flour particles are ignited by sparks, open flames, or even static electricity. Poor ventilation, mechanical friction, equipment overheating, inadequate housekeeping, and insufficient maintenance are all major contributors to the ignition of flour dust.
Implementing advanced industrial dust collection systems, regular facility inspections, and maintaining strict process cleanliness are key strategies for combustible dust hazard mitigation in these environments.
The rapid advancement of laser cutting, grinding, and automated manufacturing has increased metal dust production in industries such as aerospace, automotive, and electronics fabrication. Combustible metal dust—notably aluminum, magnesium, bronze, zinc, and silicon—can reach extreme temperatures (up to 3500°C/6332°F) when ignited, resulting in higher flame speeds and explosion overpressures than most organic dusts. Aluminum and magnesium dust, in particular, possess low minimum ignition energies, making them exceptionally dangerous in poorly ventilated workspaces or where incompatible materials are mixed. Secondary hazards arise from the possibility of thermite-like reactions between mixed metallic dusts, leading to violent thermal runaway events.
Appropriate explosion suppression systems, continuous airborne dust monitoring, and stringent separation of incompatible materials are critical recommendations for metalworking dust safety compliance.
Prevention Tip: Use grounded electrical equipment and certified anti-static flooring to reduce the risk of static-induced ignition.
Rubber dust clouds are generated by grinding, cutting, sanding, and recycling operations in tire manufacturing, automotive production, and rubber processing facilities. These fine particles are highly flammable, especially when allowed to accumulate in confined spaces, ductwork, or on equipment surfaces. Besides being combustible, rubber dust poses significant occupational health risks, including lung disease and respiratory irritation due to the chemical additives and fillers present in rubber compounds. Accumulations on machinery or in ventilation systems increase the risk of ignition from heat, electrical faults, or static discharge.
The hazardous components of rubber dust include both organic chemicals, which are toxic to aquatic life, and inorganic substances such as lead and zinc—both of which can contribute to the explosibility of the dust. Strict dust control and regular environmental monitoring are necessary to address the dual challenges of window protect worker safety and environmental regulations.
Regulatory Note: Compliance with OSHA limits for airborne particulates and National Emission Standards for Hazardous Air Pollutants (NESHAP) helps ensure workplace safety and environmental protection.
Plastic manufacturing—including processes such as molding, extruding, forming, and refining—produces significant amounts of combustible plastic dust. Accumulations are particularly hazardous due to plastics' unique chemical formulations, which can release flammable vapors or gases during thermal decomposition. Facilities processing plastics such as acrylic (PMMA), acrylonitrile butadiene styrene (ABS), Delrin/Acetal, nylon, polycarbonate, and polyethylene terephthalate (PET/PETE) face specific challenges, as these materials are highly volatile and prone to catastrophic dust flash fires when adequate dust control systems are not in place. Additionally, additives like resins, plasticizers, surfactants, and colorants can increase toxicity and explosion risk.
Best Practices: Install proper dust extraction systems, use anti-static tools, and ensure rapid removal of accumulated dust to minimize ignition risk during production or maintenance activities.
The recycling industry processes a wide assortment of materials—paper, plastics, metals, electronics—that are shredded, crushed, and conveyed, releasing hazardous recycling dust. Material blends in recycling lines can unpredictably combine various chemicals and metals, increasing the risk of spontaneous ignition, exothermic chemical reactions, and toxic emissions. Facilities often struggle with effective dust removal due to the continuous influx and mixing of waste streams, which can result in dangerous accumulation on coarse and horizontal surfaces, ventilation ducts, and machinery. As with all forms of combustible dust, recycled dust must be managed through frequent cleaning, monitoring, and the use of explosion-proof equipment.
For optimal worker safety and OSHA compliance, implement frequent air quality monitoring, explosion venting, and systematic dust clean-up schedules. Industry best practices recommend integrated dust collection and suppression systems capable of handling mixed material streams and rapid containment of unexpected ignition events.
Conclusion: Recognizing the distinct properties of various types of combustible dust is essential for reducing the risk of explosions, ensuring facility compliance with safety regulations, and protecting workers. Conducting a dust hazard analysis (DHA), integrating robust dust collection and ventilation systems, and following are vital steps for any industry susceptible to dust hazards.
The hazards associated with combustible dust explosions have prompted the development of comprehensive dust control strategies to prevent fires, secondary explosions, and worker exposure to hazardous airborne particulate matter. Effective combustible dust mitigation requires a multipronged approach, with industrial dust collectors and dust collection systems playing a central role. These engineered solutions filter and purify workplace air, safely trapping dangerous dust—including fine particles—that can otherwise accumulate on floors, beams, and machinery surfaces. However, while dust collection systems are exceptionally effective at capturing suspended particulate from facility airflows, they cannot target dust already settled on equipment, ledges, or other exposed surfaces. This shortfall means additional combustible dust control methods are needed for total facility protection.
Among the preventive measures emphasized by regulatory organizations such as OSHA, the NFPA, and the Chemical Safety Board, the most universally recommended practice for controlling combustible dust accumulation is rigorous, ongoing housekeeping. Clean, organized workspaces drastically reduce the risk of combustible dust buildup and subsequent ignition. However, standard industrial vacuums are not equipped for this specialized task—in fact, using conventional vacuums may increase hazards due to the risk of static discharge. Instead, compliance requires use of certified, purpose-built combustible dust vacuums engineered with non-static, explosion-proof features specifically designed to meet best-practice combustible dust safety standards.
The standard industrial vacuum, while powerful for general debris and certain industrial cleaning applications, presents significant safety challenges when used with combustible dust. The friction generated within a traditional vacuum hose can create dangerous static electrical charges. If this ungrounded, static-laden hose contacts grounded metal or surfaces, it may produce a spark capable of starting a dust fire or triggering a catastrophic secondary explosion. Recognizing these hazards, vacuum equipment manufacturers have developed NFPA-compliant, ATEX-rated combustible dust vacuums and cleaning systems that are intrinsically safe, static-dissipative, and suitable for use in hazardous, classified dust environments.
Combustible dust vacuums—often referred to as explosion-proof or hazardous location vacuums—are engineered specifically for cleaning up explosive and flammable materials without introducing ignition sources. These advanced systems are essential for facilities in the chemical processing, food manufacturing, pharmaceuticals, wood and metal fabrication, agriculture, and other industries that generate or handle combustible dust. The core design principle of a combustible dust vacuum is comprehensive ignition control and compliance with regular preventive maintenance guidelines critical for occupational safety and regulatory adherence. Proper combustible dust vacuum selection is vital for mitigating the risks of deflagration or flash fires.
Dust ignition proof vacuums are rigorously tested to ensure that they do not permit arcs, sparks, or generate sufficient surface heat to ignite dust clouds or settled layers in the air. For a vacuum system to be OSHA- and NFPA-compliant, it must be certified by a Nationally Recognized Testing Lab (NRTL) and fulfill applicable standards such as OSHA 29 CFR 1910.7. Selection of a vacuum should always be based on the combustible dust hazard assessment and the dust's minimum ignition energy (MIE), Kst value, and classification per the National Electrical Code (NEC).
Venturi-powered combustible dust vacuums utilize the Venturi principle—where compressed air accelerates through a constricted nozzle—creating a powerful vacuum via low-pressure zones in the mixing chamber. This design eliminates all electrical components, further lowering ignition risk. These vacuums deliver optimal airflow and suction for removing explosive dust deposits from hard-to-reach places and industrial machinery, improving overall combustible dust management. Negative pressure airflow reliably moves airborne and settled particulates through multi-stage filtration and into a collection drum, supporting stringent housekeeping protocols and lowering contamination risks.
Similar to Venturi systems, pneumatic combustible dust vacuums are exclusively air-powered, with no moving electrical parts. This reduces the potential for sparking, arcing, or friction heat, making them exceptional for Class II Division 1 and Division 2 environments where explosive dust atmospheres are present. They are lightweight, portable, operate quietly, and are designed for the safe vacuuming and removal of combustible dust in severe-duty, regulated environments, such as found in food processing, pharmaceuticals, and metalwork. Pneumatic vacuums are built for compliance with NEC Class I (gas and vapor) and Class II (combustible dust) safety codes, supporting explosion prevention protocols and protecting facility assets and personnel.
For large-scale industrial combustible dust control, many facilities employ centralized vacuum systems certified for combustible dust hazards. Unlike portable vacuums, centralized units integrate permanently with facility ductwork to handle continuous, facility-wide dust extraction from production lines, packaging areas, and storage zones. These systems include explosion isolation features, anti-spark ducting, and pressure-relief mechanisms for enhanced safety. Components include one or more powerful suction units, industrial-grade piping, ductwork, advanced filtration modules, and safety valves. Centralized vacuums efficiently move hazardous dust—such as wood, metal, sugar, spice, grain, or chemical particulates—directly to secure outdoor collection bins, improving compliance with NFPA 652 and NFPA 654 standards for combustible dust risk mitigation.
Centralized industrial vacuum systems are deployed in high-risk sectors including coal power plants, food and grain processing facilities, pharmaceutical manufacturing, plastics molding, and chemical production. Key advantages are immediate accessibility, rapid cleaning capability, reduction of airborne combustible dust concentrations, and compliance with safety audits and insurance requirements. A properly designed system—tailored for local regulations—acts as a critical safeguard within a facility’s overall explosion protection plan and dust hazard analysis strategy.
While combustible dust vacuums are essential for cleaning surfaces, combustible dust collectors are comprehensive air pollution control systems designed to remove hazardous dust and particulates from ambient facility air. These systems capture, convey, filter, and contain dust generated during bulk powder processing, packaging, conveying, and finishing operations. Industrial dust collectors are engineered to handle a variety of combustible dust types—metal, wood, flour, sugar, chemical, and other reactive dusts—and are a cornerstone of plant dust explosion prevention strategies. Proper specification and implementation of industrial dust collection equipment are critical for meeting OSHA and NFPA combustible dust safety standards.
Cyclone dust collectors leverage centrifugal force to rapidly spin contaminated air in a cyclonic chamber, separating larger dust and debris particles from the airstream without using filters. This makes them ideal for high-volume, abrasive, or fibrous dust—including wood chips, metal shavings, and mineral dust—while reducing filter wear in downstream collectors. Cyclone separators are commonly used as pre-filters paired with baghouse or cartridge systems to extend their filter life. Standard cyclone configurations include tangential spiral inlets, counterflow clean air outlets, and collection hoppers for dust disposal. Typical cyclone applications encompass paper dust removal, chemical processing, mining, and industrial gas cleaning, making them indispensable in combustible dust control plans.
The cyclonic action inside the unit forces heavier particles to the outer walls and downward into a storage drum or bag, while the cleansed air escapes via a central outlet to the next filtration stage or air exhaust, promoting environmental health and regulatory compliance.
Baghouse dust collectors remain the most prevalent and efficient industrial combustible dust collection technology. Operating with a dense array of fabric filter bags arranged within a robust metal housing, baghouse collectors remove submicron and micron-sized dust from process airflows. Each filter bag traps dust on its outer surface, letting clean air pass through. Periodic cleaning is accomplished by pulse jet, mechanical shaker, or reverse air methods, each tailored for different facility requirements and dust characteristics. Baghouse dust collectors deliver outstanding capture efficiency for wood dust, pharmaceutical dusts, powder coatings, grain dust, and other hazardous particulates, and are essential to meeting OSHA and NFPA guidelines for combustible dust collection.
The pulse jet cleaning cycle utilizes bursts of compressed air timed to maintain collection capacity and minimize maintenance downtime. Shaker baghouses use a mechanical shaking mechanism to dislodge dust when compressed air is not available. Reverse air units clean filters with an internal airflow stream, extending filter life and reducing re-entrainment of hazardous dust. Facility managers should assess air-to-cloth ratios, static pressure requirements, and filter media compatibility to optimize baghouse collector performance for specific combustible dust profiles.
Wet dust collection systems are highly effective for managing combustible dust that poses a significant explosion hazard, particularly hygroscopic, sticky, or fine particulate matter prone to static ignition. By combining atomized water or liquid scrubbing agents with incoming dust-laden air, wet collectors rapidly quench ignition sources and remove hazardous dust from the airstream through intensive scrubbing action. Typical wet collectors utilize cyclonic or Venturi designs, integrating both physical and chemical means to capture and neutralize explosive dust. These units are especially useful for facilities where dust is prone to spontaneous ignition or where combustible metal dust—aluminum, magnesium, or titanium—is prevalent. Wet dust collectors are integral for compliance with EPA air quality standards and NFPA 484 metal dust requirements.
The operational cycle involves dust-laden air entering the unit, passing through a water spray or fluid bath that immediately binds explosives and removes suspended particles, and then gravity-separation of collected slurry into a secure reservoir. Applications include pharmaceutical manufacturing, plastics machining, food processing, and chemical blending, all of which generate fine, reactive, or water-absorbent dust.
Cartridge dust collectors represent a space-saving, highly efficient solution for fine particulate and smoke, such as dust generated from welding, thermal cutting, laser processing, and pharmaceuticals. Their pleated filter cartridges offer a larger surface area in a compact design compared to traditional bag filters. Airborne dust is drawn through the cartridges, which capture particles down to 0.3 microns before returning clean air to the facility. For fire safety, these systems can be outfitted with explosion vents, deflagration isolation valves, and anti-static filter media to address specific combustible dust risks. However, operators should note that cartridge dust collectors are not recommended for sticky, fibrous, or damp dusts which may cause filter blinding and maintenance challenges.
The four combustible dust collector types described are widely adopted as core components of industrial dust control and explosion prevention programs. Each collector must be selected based on dust characteristics, facility layout, and regulatory compliance needs. Not all dust collectors are certified for combustible dust collection—always consult with manufacturers experienced in designing NFPA- and OSHA-compliant dust collection systems tailored for specific hazardous dust types and facility challenges. Facility managers should perform a comprehensive dust hazard analysis (DHA) before purchasing or upgrading any dust collection equipment, ensuring the system mitigates deflagration risks throughout the dust lifecycle.
Managing combustible dust in hard-to-access or confined areas remains a complex challenge, often addressed by high-velocity dust control fans. Designed to create powerful airflows, these industrial fans disperse and direct dust accumulation from rafters, equipment, corners, and other difficult locations toward central collection points. Despite their simplicity, control fans form an essential piece of the combustible dust safety puzzle, improving workplace air quality and visibility, and supporting compliance with combustible dust clearance and safety standards. Their high-speed blades and protective grills enable targeted, efficient cleaning in warehouses, assembly plants, and overhead structural spaces.
The efficiency of high-velocity fans stems from their capacity to move large air volumes rapidly—crucial for expelling fugitive dust from potential ignition regions. These fans can be paired with air filtration, dust collection, or ventilation systems as part of an integrated combustible dust management strategy. They are often deployed to facilitate cleaning of wood dust, plastics, metalworking debris, food and grain dust, and other combustible particulates, helping facilities address both OSHA workplace safety requirements and insurance provider recommendations.
Combustible dust has been a destructive force in several industries, which has necessitated the development of regulations and standards that outline the proper handling and cleaning of dust filled air. For an air cleaning system to be approved as a combustible dust handler, it has to be approved by testing labs listed by OSHA.
The classification of combustible dust falls into a unique set of parameters that are considered when defining a particular type of dust. The classification system for combustible dust helps in assessing and managing the potential risks of dust in industrial environments. It is a standardized framework for understanding the explosiveness, danger, and hazards related to different forms of dust.
The factors used to classify combustible dust are particle size, particle shape, and the moisture content of the dust. The size and shape of dust particles determine their surface area and reactivity. Fine particles are more reactive and combustible, a factor that leads to rapid combustion or dust explosions. Dust with a high moisture content is less prone to ignition, which affects its classification.
The factor that is the most impactful in determining the combustibility of a dust is its chemical composition, which directly relates to its volatility. Varying levels of substances in dust determine its combustibility and strongly influences how hazardous and explosive a dust may be. In addition to the chemical content of one dust, there is also the factor of the combination of different dusts that may add to their combustibleness.
Pmax and Kst are two common measures of the explosiveness and combustibility of dust. While these two factors are not the total range of parameters that can determine the explosiveness of a dust, they serve as major guidelines. Pmax and Kst are measurements of air pressure and are used to test the volatility of a dust in carefully controlled laboratory conditions.
| Kst Classes | |||
|---|---|---|---|
| Powder Class | Kst Value | Effect | Dust Type |
| St 0 | 0 | Does Not Explode | silica, welding, cutting processes |
| St 1 | 1 to 200 | Weak Explosion | charcoal, powdered milk, sugar, sulfur, wood dust, zinc |
| St 2 | 201 to 300 | Strong Explosion | cellulose, wood flour, poly methyl acrylate (PMA) |
| St 3 | greater than 300 | Severe and Damaging Explosion | Metal dust from aluminum, magnesium, and titanium |
The NEC classifies hazardous locations as to a location's potential for causing a fire or explosion due to the presence of gases, vapors, liquids, combustible dust, and ignitable fibers. The classification process is divided into Class I, Class II, and Class III, with Class II used to define the dangers of combustible dust. Under each class are divisions or zones that identify the conditions for the occurrence of an explosion. In addition to the divisions or zones are the groups that define the necessary ignition properties that are in the atmosphere.
Class II locations have a sufficient amount of combustible dust capable of creating an explosion and are ignitable. Division 1 under Class II includes areas where combustible dust normally exists and is part of everyday operations. Division II is where combustible dust does not exist or only exists due to an abnormal or uncharacteristic event. The dust from Class II is divided into groups categorized by NEC as E, F, and G, which are grouped according to auto ignition temperature and substance conductivity. Of the two grouping factors, conductivity is the most important in regard to the explosive characteristics of dust.
Group E includes St 3 dust, which is dust from aluminum, magnesium, and their alloys. Also included are combustible dusts whose particle size, abrasiveness, and conductivity are part of the hazards of using electrical equipment.
Group F includes St 1 dust that contain combustible carbonaceous dusts that include coal, coke, carbon black, and charcoal dust with 8% entrapped volatiles or dust that has been mixed with other materials to produce an explosive hazard.
Group G is an all-inclusive classification that includes dusts that have not been covered in Groups E and F. Dusts in this group include agricultural dusts, such as flour, cocoa, starch, grain and wood, thermoplastic resins, molding compounds, pharmaceutical drugs, and chemical powders.
The American Society for Testing and Materials International (ASTM), NFPA, and OSHA have regulations and standards regarding the identification, handling, and safety conditions for combustible dust. OSHA is a federal government group while ASTM has been accepted as an international set of standards. The focus of the NFPA is on conditions that will lead to fires and explosions and has a long list of regulations regarding combustible dust.
A general industry standard that requires companies to maintain clean workplaces as a method for preventing hazards. The regulation stipulates the importance of proper housekeeping and dust removal.
This requirement is in regard to the use of equipment in hazardous locations, such as areas where combustible dust exists. It sets the standard for industry safety related to hazardous locations where combustible dust is present and outlines safety measures, equipment requirements, and training.
This standard addresses hazards regarding grain handling and mandates the use of dust control measures and safety procedures to protect workers.
Outlines Standard Test Method for determining the Explosibility of Dust Clouds with procedures for performing laboratory tests to evaluate deflagration parameters. The data collected can be used to determine the size of deflagration vents using equations published in
NFPA 68, ISO 6184/1, or VDI 3673. Methods and procedures used are specific to the tested sample.
Standard Test Method for Minimum Explosible Concentration of Combustible Dusts provides procedures for performing laboratory tests to evaluate relative deflagration parameters of dusts.
As may be assumed, the list of standards for the NFPA is very long and specific covering a plethora of potential hazards.
NFPA 61: Standard for the Prevention of Fires and Dust Explosions in Agricultural and Food Processing Facilities
NFPA 68: Standard on Explosion Protection by Deflagration Venting
NFPA 69: Standard on Explosion Prevention Systems
NFPA 70: The National Electrical Code (NEC)
NFPA 499: Recommended Practice for the Classification of Combustible Dusts and of Hazardous (Classified) Locations for Electrical Installations in Chemical Process Areas
NFPA 652: Standard on the Fundamentals of Combustible Dust
NFPA 654: Standard for the Prevention of Fire and Dust Explosions from the Manufacturing, Processing, and Handling of Combustible Particulate Solids
NFPA 655: Standard for the Prevention of Sulfur Fires and Explosions
NFPA 664: Standard for the Prevention of Fires and Explosions in Wood Processing and Woodworking Facilities
Above and beyond the list of regulations listed above there are several international organizations that have stipulations, standards and regulations regarding combustible dust that include European Committee for Standardization, Verein Deutscher Ingenerie, The International Fire Code (IFC), and the International Organization for Standardization (ISO). Each of these organizations are aware of the dangers and hazards related to combustible dust and have relegated substantial resources to its control and prevention.
One of the problems related to combustible dust is in regard to underestimating the dangers it presents and overlooking it until it causes a major problem. As has been evidenced by several companies in the recent past, neglecting combustible dust can lead to devastating and catastrophic disasters and the total and complete destruction of a facility.
Dust in the woodworking industry comes from cutting, sanding, or other methods for processing wood products. The fine wood particles become suspended in the air creating an explosion hazard that can lead to flash fires and explosive conditions if ignited. Places susceptible to such circumstances are sawmills, carpentry shops, furniture manufacturing companies, and lumber processing plants.
Anyone who has ever worked on a farm knows of the many types of dust that are generated through the handling of wheat, corn, hay, and other plants. Grain handling and storage generates a huge volume of dust that is allowed to dissipate into the air. The dust becomes more dangerous when isolated in confined spaces where it can explode if ignited. Aside from activities on the farm, dust from agricultural products can be prevalent in bakeries, flour mills, pasta production facilities, and other forms of food processing.
Chemical industries that produce pharmaceuticals, dyes, and pigments create chemical dust that include coal and sulfur, which are flammable in particulate form. Unlike other types of dust, dust from chemical manufacturing has the additional challenge of being reactive with potential toxicity from the combustion of the chemicals. In addition, the interaction between chemical dust can cause a dangerous reaction if not sufficiently controlled. Many of the safety efforts of chemical companies are devoted to controlling and managing the generated dust.
Biosolids come from wastewater treatment facilities and organic processing, which generate explosive combustible dust when there is a buildup of dry residue. The dust that is created is the most explosive type and has extremely fine particles. Stringent safety standards are applied to the handling of biosolids that include adequate ventilation and documented safety protocols.
Metal dust is generated from the grinding, abrasive blasting, cutting, and polishing of metals. The consistency of metal dust is due to the combustible nature of the metals when reduced to a fine dust. The ignition of metal dust can result in violent explosions with intense destructive fires. The metals that predominantly produce metal dust are aluminum, magnesium, titanium, and steel, which are the most common metals used to produce metal products.
The molding, extrusion, and recycling of plastics produces volumes of metal dust that is highly explosive due to the plastic resins used to produce plastic material. As with metal, plastic dust has very fine particles that have a higher potential of exploding.
The few industries described above are a sampling of the many types of combustible dust that are generated from the production and manufacture of popular products. Additional industries that produce combustible dust as part of their manufacturing are power plants, mining operations, and synthetics production that produce polyesters, nylon, and other artificial fibers. The textile industry, that produces fabrics for the manufacture of clothing, produces dust from cotton and synthetic fibers.
The prevalence of dangerous and toxic dust is a major concern of modern manufacturing that has developed methods for controlling and monitoring the presence of dust in their facilities. Although certain segments of society may overlook the need to prevent the accumulation of dust, companies that produce products that generate dust are dedicated to preventing combustible dust from becoming a major problem and use every method available to manage the situation.
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