Disclaimer: The contents of this industrial dust blog are intended to be general safety guidelines. All businesses will still need to refer to OSHA, NFPA, and local ordinances required for their business.
Industrial Dust Guide
Dust builds up in your home may simply be a nuisance you take care of while spring cleaning. But in the workplace, dust can become a serious hazard if not properly handled. To get a better understanding of the negative effects of dust in the workplace we will provide a brief overview what industrial dust is, how industrial dust is created , potential dangers you should plan for, and the benefits of a properly engineered dust collection system.
What is Industrial Dust & How is it Created?
Dust consists of small particles of dry matter that build-up on hard surfaces such as floors, tools, industrial equipment, ducts, etc. Industrial dust can generate more frequently than household dust. This is because it generates from the daily from the manufacturing or production process. For example, a small woodworking shop could generate dust from activities like sawing, grinding, or cutting. Industrial dust can even break out during processing. Another example, in an agricultural facility process dust can come from sugar, flour, grains, etc.
Common Types of Industrial Dust
- Wood – Activities like sanding, high speed cutting, low speed cutting, paning etc. can create dust which is both explosive and fire prone.
- Food Particulate– Certain food particulate can be explosive, abrasive and fire prone. This can encompass a wide variety of particulate such as flour, grains (corn, rice), soybeans, and more.
- Cement & Concrete – This dust is abrasive but considered to be less explosive and prone to fire.
- Paper Products – Dust created from paper products can be both explosive and fire prone.
- Paint Powder – Paint pigments can be highly explosive
- Pharmaceuticals – Pharmaceutical dust like dry powder and coating are both explosive and fire prone.
- Plastic, Chemicals, Stone, Minerals , Metal etc.
Is Industrial Dust Dangerous?
The build-up of combustible dust is serious hazard in the workplace. Airborne dust presents a safety hazard to employees. Many types of industrial dust may contain carcinogenic properties that would require removal to keep employees safe, healthy, and to comply with government regulations.
Airborne dust may also be highly flammable, and safeguards must be implemented to prevent the risk of a dust explosion.
Conditions for a Dust Explosion
- Enclosed space
- Ignition source
- Combustible dust at the right concentration level
When you are working in an industry that operates with combustible dust, explosions and fires are a constant threat. If you are taking the right steps to ensure a safe working environment you are more likely to avoid a fire or explosion that would cost you the safety of your employees, thousands of dollars in lost production, and regulatory fines. Combustible dust can present itself in a variety of applications. Below are just some of the types of industries that work with combustible dust.
Common Examples of Combustible Industrial Dust
- Agriculture (grain, flour, sugar, etc.)
- Metals (aluminum, zinc bronze, etc.)
- Chemicals (coal, Sulphur, etc.)
There are no short cuts to minimizing dust hazards and ensuring the safety of your employees. But understanding if you are working with combustible dust is the first step in prevention.
Regulation of Air Pollution Control
Many industrial industries in the U.S. must comply with strict air pollution control standards. These standards are set by the Environmental Protection Agency (EPA), National Fire Protection Agency (NFPA), OSHA, or local governing entities like the AQMD in California.
OSHA regulates industries that are susceptible to combustible dust. When implementing OSHA’s set of standards, you are creating a safe working environment, avoiding property and economic loss from an explosion, avoiding regulatory fines. To learn more about OSHA’s safety standards for combustible dust, visit their guide here.
The NFPA (National Fire Protection Agency) is another agency that publishes a list of guidelines to help minimize injury or death from combustible dust. The following codes are related to the most combustible types of dust (e.g., sugar, wood, fine aluminum):
- 664, Standard for the Prevention of Fires and Explosions in Wood Processing and Woodworking Facilities
- 484, Standard for Combustible Metals
- 61, Standard for the Prevention of Fires and Dust Explosions in Agricultural and Food Processing Facilities
How a Properly Engineered Dust Collection System Supports Air Pollution Control
Dust collection systems are engineered and designed to filter airborne industrial dust particles and debris that can cause damage to plant equipment, create a hazardous work environment, and negatively impact plant production. The top 5 benefits of a dust collection system are:
- Meet Compliance Regulations and Standards – All agencies require industrial facilities to maintain and meet air quality standards to ensure a safe and clean environment for their plant, employees, and the surrounding community.
- Boost Productivity – An accumulation of dust particles and debris on industrial equipment can interfere with overall plant performance. A dust collection system can collect these dust particles before they can interfere and compromise the health and performance of your manufacturing equipment.
- Improve Product Quality – Dust can settle and accumulate on products during the manufacturing process. This has a negative impact on the quality and consistency of finished goods. A dust collector will reduce and effectively capture these dust particles, allowing for product quality to improve and maintain consistency.
- Enhance Health and Safety Standards – Inhalation of hazardous dust affects human health and a dust collection system is vital to removing these hazards and to keep employees safe.
- Preserve the Quality of Equipment – As dust particles and debris are created inside a manufacturing facility, the contaminated dust will settle onto other surfaces such as computer systems and manufacturing equipment. This dust buildup can be harmful and result in malfunctioning equipment. It can also create unnecessary, frequent, and costly maintenance to keep dust and debris from accumulating. With a dust collector system purifying and collecting dust particles, the chances of excessive dust build-up is minimal.
Baghouse Dust Removal Options
- Enclosed Box – A simple pipe system funneling dust into an enclosed box, placed underneath your hopper, is one dust removal option.
- Drum or Bag – A removable drum or bag can be a simple and easy solution to collecting and disposing dust.
- Rotary Valve – Rotary valves (also known as airlocks, rotary feeders, or airlock feeders) help transition material from a dust collector to a drum or bin.
- Screw Conveyor for Baghouse Dust Collectors – Large baghouses with heavy dust loads typically use screw conveyors. The screw conveyer would transport dust away from the collector, then send it to a designated disposal area.
The best method of dust removal from your hopper is dependent on some of the following components:
- What’s your Dust Collector Type? Baghouse or Cartridge Dust Collector?
- What are the characteristics of your dust? For example, hazardous or non-hazardous?
- What are the loading rates of your dust?
Explosion Venting Strategies
Common Venting Strategies
•Preventative Maintenance Plan: In conjunction with a protection strategy, every facility should implement a well-designed and operated preventative maintenance plan. Perform regular checks on the health of your dust collection system to prevent more serious issues.
•Explosion Vent or Panels: Explosion vents or panels are designed to rupture at a set pressure (PStat). When a source of ignition meets a fuel source with sufficient oxygen present, an ignition will occur. As the ignition begins, the pressure inside of the vessel will increase rapidly. Depending on the material’s Kst value, the pressure rise may be slow or extremely rapid. As the ignition progresses, the internal pressure will meet the PStat rating of the explosion panel. The explosion panel will rupture, venting the ignition gasses. The explosion vent provides a relief avenue for the expanding gasses, but the pressure in the vessel will continue to rise until it reaches the Pred pressure. This is the maximum pressure of the ignition event when explosion vents are functioning, so this is usually the pressure rating the vessel is designed to withstand.
You can use explosion panels with a short length of ducting to allow for interior use without flameless venting. They do require replacement once a rupture occurs, but they are simple, cost-efficient, and easy to install. Explosion vents are typically useful on baghouses and cartridge dust collectors.
• Explosion Latch: Explosion latches work under the same principle as the explosion panels, but they are not single use. This is a more cost-effective option (versus explosion panels) when you have a large baghouse or large quantity of vent area.
Additional Venting Strategies
• Flameless Venting: Flameless venting can consist of a flame arrestor element, vent panel, and flanged housing. This combines the techniques of explosion venting and flame arresting. You can also install a flame arrestor element over a standard explosion vent. When the vent ruptures, the burnt dust and flames enter the flame arrestor element. The element helps to contain the hazardous dust and flames and prevents it from exiting, where it could potentially ignite a secondary explosion or endanger employees. While flameless venting does stop flames from exiting the vessel, there will be extremely hot gasses exiting the flameless vent. When using flameless venting, make sure to pay close attention to the vents proximity to personnel areas. If possible, always aim flameless vents away from regularly occupied areas.
• No Return Valve: Protecting the dust collector from over-pressure is essential, but it is equally important to stop a deflagration propagation back to the operator space. To prevent this, a No Return Valve is needed in the inlet duct. This valve is a weighted damper that is held open by the air flow during normal operation, allowing air and dust to pass through to the dust collector. In the event that deflagration occurs in the dust collector, the pressure propagation through the duct work will close the No Return Valve. This prevents the deflagration from reaching any process equipment and also limits the risk of secondary explosions.
• Abort Gate: Abort gates are high speed dampers that contain a spring assisted blade and is typically held in place by an electromagnet. Their purpose is to minimize the risk of an explosion by diverting flame, spark, or debris from entering a facility through a return air system.
• Spark Detection & Extinguishing System: This method uses infrared sensors, typically located on the ductwork, to detect sparks or burning material in the ductwork upstream.
Secondary Event Protection
All the methods described previously are excellent options for managing primary explosions, but one of the most catastrophic outcomes of a combustible dust explosion is an un-controlled secondary explosion.
When a primary explosion happens, there may be a pressure wave that propagates through the plant. This will “kick up” the layer of ambient dust. If the explosion is not contained in the dust collection system using the methods previously outlined, this ambient dust in the air could come in contact with the primary explosion flame front. This results in an uncontrolled explosion in an occupied space.
To minimize the risk of secondary explosions, the first step should always be to expect perfect performance from your dust collection system. It is not acceptable to have a dust collection system that does not function properly. Another suggestion is to limit the amount of horizontal surfaces in your plant that cannot be regularly cleaned. Drop ceilings and in-accessible equipment are great examples of this.
There are many strategies that may fit your unique application or facility. We recommend to consult your local or state building codes and regulations before choosing your explosion venting strategy. Some areas will have specific regulations for fire safety and environmental safety, and you want to ensure you are meeting those guidelines. Here are some questions to consider before implementing an explosion venting strategy.
Questions to Consider
- What are the state and/or local regulations for fire safety and explosion venting that will protect my staff and facility?
- Is the dust collector setup inside or outside?
- What is the distance of the dust collector from the roof or walls?
- Is the dust collector or vent close to any other structures?
- What’s the cost?
At U.S. Air Filtration, we have been eliminating the hazards of industrial dust for 35 years.
To learn more about how you can manage industrial dust at your facility contact us at 888-221-0312 or [email protected] to speak with an engineer