Is Your Dust Combustible?

August 22, 2020

Is Your Dust Combustible?

One of the most crucial factors in your choice of an industrial vacuum system is the type of dust you’ll be collecting. Combustible dust is a major safety hazard across industries, from pharmaceuticals to food and beverage production. Unfortunately, it’s all too often overlooked. 

Whether you’re overhauling your health and safety program to ensure compliance or seeking to better understand your options for collecting and controlling particulate solids, you’re in the right place. As you search for an industrial vacuum system that fits your specific industry, facility, and dust collecting needs, it’s critical to familiarize yourself with the safety standards and potential risks surrounding this type of dust. We’ve put together a straightforward guide to help you navigate this issue and arrive at the ideal industrial vacuum solution. Read on for information on what causes combustible dust explosions, how to determine whether the dust generated by your manufacturing process is combustible, and what you can do about it.

What Is Combustible Dust?

Regulatory bodies around the world have different definitions for this term. In the U.S., combustible dust refers to any material consisting of distinct particles that may catch fire or combust when mixed with air. This kind of material can be created by a number of different processes, including grinding, screening, transporting, and simply handling dry materials.

Types of Combustible Dust

In addition to the many processes that produce combustible dust, there are numerous materials that can combust under the right conditions. That includes fine particles created from organic substances like egg whites, sugar, and flour, as well as metals like zinc, aluminum, and magnesium. For further combustible dust examples, see this chart from the Occupational Safety and Health Administration (OSHA). 

The bottom line here is that if your facilities or manufacturing processes generate any kind of dust, you, your employees, and your facility could be at risk.

Dangers of Combustible Dust

In 2008, a large buildup of combustible dust in the packaging facility of a Georgia sugar refinery caused a catastrophic explosion, resulting in 14 deaths and 38 injuries. The Imperial Sugar explosion of 2008 is frequently referenced as the incident that brought combustible dust to the forefront of health and safety concerns across the production and manufacturing sectors.

Combustible dust burns rapidly. Under the right conditions, this results in near-instant deflagration—an extreme release of air pressure that can bring down buildings and cause devastating injuries and deaths. Not every incident is as severe as the Imperial Sugar explosion, however. In fact, more combustible dust events involve fires than explosions. 

In 2019, the United States saw 175 fires and 37 explosions caused by combustible dust. These incidents resulted in 42 injuries and one fatality. Perhaps the most staggering takeaway from this data is that the vast majority of both fatalities and injuries were attributed to explosions. So what, exactly, gives rise to these deadly events?

What Causes Combustible Dust Explosions?

A total of five factors must be present for a combustible dust explosion to occur:

  • Combustible dust
  • Oxygen in the air
  • Confinement of the dust cloud
  • A heat source for ignition
  • Dispersion of dust particles

Together, these factors are known as the “Dust Explosion Pentagon.” If even one of the five is absent, an explosion can’t occur. This only serves to illustrate the extreme importance of controlling and limiting these elements in your workplace.

How Do I Know If My Dust Is Combustible?

As we mentioned previously, any manufacturing process that involves the production of dust carries the potential for combustible dust explosions. Industries and processes that are particularly at risk include, but are by no means limited to, the following:

  • Food/beverage production
  • Pharmaceutical production
  • Metal processing
  • Woodworking

Dust Type Testing

To determine whether your dust is combustible, you’ll need a dust type test. This involves finding a reputable testing company and sending in a sample of every type of dust present in your facility. That company will evaluate your dust and calculate a variety of key variables that can help you determine whether your dust is combustible and how much of a risk it presents.

Here are some of the values that are typically calculated as part of a dust type test:

  • Minimum Ignition Energy (MIE): the smallest possible amount of energy required to ignite your dust
  • Minimum Explosion Concentration (MEC): the minimum concentration of a combustible dust cloud (i.e., dust present in the air) that will cause an explosion
  • Maximum Rate of Pressure Rise/Deflagration Index (KST): how strong your combustible dust explosion would be
  • Minimum Inerting Concentration (MIC): the lowest possible dust concentration that will not cause an explosion, regardless of the amount of fuel present

Combustible Dust Laws and Standards

The Imperial Sugar explosion was the inciting factor in the creation of multiple nationwide regulations. It also gave rise to some legislative efforts—the Worker Protection Against Combustible Dust Explosions and Fires Act was introduced on four separate occasions, but it failed to pass. While there is currently no federal law mandating the treatment and mitigation of combustible dust hazards, there are set standards in place.

The Occupational Health and Safety Administration (OSHA) developed the Combustible Dust National Emphasis Program over a decade ago. This program allows OSHA to inspect facilities in industries that come with combustible dust hazards, but it doesn’t allow the organization to cite a company for violating guidelines. Instead, these citations (and the fines that follow) are typically issued based on the General Duty Clause, which states that companies must provide a safe workplace for their employees.

The National Fire Protection Association (NFPA) is not an enforcing organization like OSHA; rather, it issues guidelines that such authorities having jurisdiction (AHJs) often reference during facility inspections. NFPA 652: Standards on the Fundamentals of Combustible Dust contains instructions for all facilities that may generate this hazardous material.

To ensure compliance and the safety of your workforce, you’ll need a comprehensive hazardous dust program. This should include a record of your dust testing, housekeeping procedures, and combustible dust control efforts. A significant portion of your dust control will be accomplished by a collection or extraction system. OSHA recommends only using equipment designed with combustible dust in mind. This begs the question: how do you choose the right industrial vacuum system for your facility?

Choosing an Industrial Vacuum System for Combustible Dust

Sorting through your options can feel overwhelming. How do you know that you’re purchasing the correct equipment? Are you already out of compliance with NFPA standards and OSHA recommendations? We’ve collected some frequently asked questions (and their answers!) below so that you can ensure you’re on the right track to safely and effectively controlling combustible dust hazards in your facility.

What Standards Do I Need to Follow for Combustible Dust?

We’ve already mentioned NFPA 652, which contains standard operating procedures for combustible dust control across industrial manufacturing sectors. There are also industry and commodity-specific standards that contain further instructions. The organization is in the process of consolidating these separate guides into one all-encompassing standard. Until then, however, compliance is still essential.

  • For metal or alloy particulate solids, you’ll need to reference NFPA 484: Standard for Combustible Metals.
  • If you’re dealing with agricultural or food product particulates, see NFPA 61: Standard for the Prevention of Fires and Dust Explosions in Agricultural and Food Processing Facilities.
  • For particulate solids generated by wood processing or woodworking, refer to NFPA 664: Standard for the Prevention of Fires and Explosions in Wood Processing and Woodworking Facilities.
  • Finally, for particulate solids consisting of sulfur, see NFPA 655: Standard for Prevention of Sulfur Fires and Explosions.

Dust Hazard Analysis

NFPA 652 also requires companies to complete a dust hazard analysis (DHA) for new processes and facilities, as well as existing ones. This evaluation involves a careful review of all areas in your facility that might house combustible dust. If any of these areas are categorized as a hazardous environment, you’ll need to document your current hazard management procedures, potential additional safety measures, and appropriate operating ranges. The DHA must be reviewed and updated every five years.

If you have yet to achieve compliance, you still have some breathing room: the dust hazard analysis deadline has been pushed back to September 7, 2020, while some industry-specific deadlines have been pushed back even further.

Do I Need an NRTL-Certified Vacuum?

If your facility produces or handles combustible dust, an explosion-proof vacuum system should be part of your dust collection and management program. Electrical equipment can be certified as explosion-proof by a Nationally Recognized Testing Laboratory (NRTL). This is the only relevant certification out there—an NFPA-certified industrial vacuum does not exist! 

When purchasing your industrial vacuum system, be sure that you’re sourcing your machinery from a reputable supplier. Explosion-proof vacuums perform an essential function, and you need to be able to count on the integrity of your equipment.

What Do I Need for Handling Combustible Dust in a Non-Rated Environment vs. a Hazardous Location?

The answer to this question is that it depends. It’s overwhelmingly likely that you’ll still need a specialty vacuum system for a non-rated environment. NFPA 652 lists specific standards for equipment used to collect combustible dust regardless of whether it’s located in a classified/hazardous or non-rated location. If you’re in a non-rated environment and you’re not handling a combustible dust, however, you should choose an ordinary location vacuum system.

At Delfin, we designed our entire Class II Division 2 product line to be in compliance with NFPA guidelines for handling combustible dust in a non-rated environment or in a Class II Division 2 HazLoc area. If you’re dealing with a Class II Division 1 hazardous location, you’ll need additional protection and a vacuum designed specifically for that dust.

What Qualities Do I Need to Look for in an Industrial Vacuum?

Now that you’re familiar with the hazards of your facility’s combustible dust, you’ll need to institute an industrial vacuum system that will perform reliably. To narrow down your options, ask yourself the following questions:

  • Am I handling a combustible dust? If the answer is no, you can begin looking at ordinary location vacuums. But if you are handling a combustible dust, you’ll need to know what class, division, and group your environment falls into. From there, an industrial vacuum professional will be able to help you identify what kind of system will best fit your needs.
  • What type of power is available? Do you have compressed air or three-phase power? Electric or pneumatic? If electric, what type of electricity is available? If air-powered, do you have sufficient air available?
  • Will you require continuous use or intermittent use? How often and for how long will you be using your industrial vacuum system? This will allow you to determine what type of motor you need. If you’ll be turning the vacuum on and off regularly, for example, you’ll need an intermittent use motor in single phase. For 24/7 use, a brushless motor for single phase would be more appropriate.
  • What are you collecting? Is the product sticky, wet, dry, abrasive, toxic, hot, etc.? This information will allow you to determine the kind of filtration and tools you’ll need.
  • How much product are you collecting? This question determines what capacity you’ll need in your industrial vacuum system, as well as canister size, filter size, and more.
  • How many simultaneous users will be on the system? The number of users, distance from the vacuum that they’ll need to go, and the diameter of the hose will determine the type of flow and pressure you need in your industrial vacuum.
  • Do you want a fixed system with piping or a portable vacuum? Or maybe even a hybrid? If you’re collecting dust in multiple rooms, you may need a fixed system with piping that goes to multiple rooms or a portable system—it depends on your industry and the type of product you’re picking up. Food manufacturers, for example, need to be especially wary of cross-contamination and allergens.

Once you’ve outlined your needs, you’ll be prepared to identify the right industrial vacuum system for combustible dust collection in your facility.

Certified Vacuum Systems From Delfin

Although there are currently no federal laws governing combustible dust, you can’t afford to ignore this potential hazard. Combustible dust represents a substantial threat, both to the health and safety of your employees and to the continued success of your company. This issue will only become more critical as the dust hazard analysis deadline approaches, regulations are consolidated, and OSHA begins to enforce combustible dust standards more strictly.

Delfin is perfectly positioned to equip you with the right specialty vacuum system for your needs. We’ll put our technical knowledge and industry experience to work by matching you with a competitively-priced, explosion-proof vacuum system that fits neatly into your combustible dust control and collection program. If you have further questions about combustible dust or want to learn more about what kind of industrial vacuum system will best fit your facility, contact us today.

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