Guide to Combustible Dust Regulations Now Available
Combustible dust continues to be a key safety concern for manufacturers, grain handlers and OSHA inspections. Workers in many industries who handle combustible solids may be exposed to combustible dust incidents that can cause catastrophic destruction, injuries and deaths. Although federal OSHA has created a variety of resources to address this hazardous condition, many states have additional codes and regulations regarding dust that you must comply with – or face penalties.
Industrial vacuum systems are a key component of dust control procedures, and Nilfisk, a maker of industrial floorcare equipment, vacuum cleaners and high-pressure washers, has prepared a guide to combustible dust codes and resources. It gives a clear state-by-state overview and provides the information you need to stay safe and compliant.
Combustible Dust Regulations Vary by State
The state-level regulations surrounding combustible dust are complex. Most states start with the same basic foundation – e.g., codes and standards developed by OSHA, the National Fire Protection Association (NFPA), and the International Code Council (ICC). But then they each put their own twist on the rules, for example, by adopting different editions of the codes, or sometimes only parts of a code, and making modifications. And, in some states, building and fire codes are established and enforced at the local level.
For example, California has one of the country’s most stringent OSHA-approved state plans. Title 8, Section 5174 outlines the regulations for controlling combustible dust. According to this standard, the preferred method of cleaning is with a permanently installed grounded vacuum cleaning system. California has adopted the 2015 versions of the International Building and Fire Codes. In contrast, Indiana’s OSHA-approved state plan is identical to federal OSHA. In October 2018, Indiana was put under a Local Emphasis Program for Grain Handling Facilities. The state has adopted the 2012 International Building and Fire Codes.
Wherever your facility is located, you must comply with all applicable regulations in your area. The Nilfisk guide includes a list of state-level resources that include specific guidance on combustible dust when available, as well as links to state OSHA offices, labor departments and safety programs, building commission and fire marshal websites, and more.
Protecting Workers from Combustible Dust Explosion Hazards
Combustible dusts can fuel flash fires or explosions when dispersed in a dust cloud. Controlling dust will help avoid incidents. OSHA recommends three key steps to control dust:
- Capture dust before it escapes into a work area by using properly designed, installed, approved and maintained dust collection systems.
- Contain dust within equipment, systems or rooms that are built and operated to safely handle combustible dust.
- Clean work areas, overhead surfaces and concealed spaces frequently and thoroughly using safe housekeeping methods to remove combustible dusts not captured or contained.
What Is Combustible Dust?
According to OSHA, combustible dust is a solid material composed of distinct particles or pieces, regardless of size, shape, or chemical composition, which presents a fire or explosion hazard when suspended in air or some other oxidizing medium over a range of concentrations. They are often either organic or metal dusts that are finely ground into very small particles, fibers, fines, chips, chunks, flakes or a small mixture of these.
Dust particles with an effective diameter of less than 420 microns (those passing through a U.S. No. 40 standard sieve) meet the definition. However, larger particles can still pose a hazard (for instance, as larger particles are moved, they can abrade each other, creating smaller particles). In addition, particles can stick together due to electrostatic charges accumulated through handling, causing them to become explosive when dispersed. Types of dusts include, but are not limited to: metal dust, such as aluminum and magnesium; wood dust; plastic or rubber dust; biosolids; coal dust; organic dust, such as flour, sugar, paper, soap, and dried blood; and dusts from certain textiles.
What Causes a Dust Explosion?
OSHA notes that five elements are necessary to initiate a dust explosion, often referred to as the “Dust Explosion Pentagon.” The first three elements are needed for any fire:
- Combustible dust (fuel);
- Ignition source (heat); and,
- Oxygen in air (oxidizer).
Two additional elements must be present for a combustible dust explosion:
- Dispersion of dust particles in sufficient quantity and concentration; and,
- Confinement of the dust cloud.
If any of the five elements above are missing, an explosion cannot occur.
The ease of ignition and the severity of a dust explosion are typically influenced by particle size. Other factors that influence the explosiveness of dusts include moisture content, ambient humidity, oxygen available for combustion, the shape of dust particles and the concentration of dust in the air.
An initial (primary) dust explosion could shake loose accumulated dust or damage containment equipment, such as ducts or collectors. If the dust becomes airborne, the additional dust can ignite and cause secondary explosions – which can be more destructive than the primary explosion, due to the increased quantity and concentration of dust and the larger ignition source.
How to Prevent Dust Explosions
OSHA’s booklet Combustible Dust in Industry: Preventing and Mitigating the Effects of Fire and Explosions lists measures to control dust, eliminate ignition sources and limit the effects of explosions. Initial preventative steps are to contain combustible dust to areas that are properly designed and located, with ignition sources either eliminated or controlled. Equipment or spaces such as ducts, dust collectors, vessels and processing equipment that contain combustible dust should be designed to prevent leaks and minimize the escape of dust into work areas.
Workers can help by removing any dust that settles on workplace surfaces through a routine housekeeping program. Areas or equipment potentially subject to explosions, including the dust collection system, should be designed to relieve pressure safely or be provided with proper suppression or explosion prevention systems.
Combustible Dust Resources:
- Download the Nilfisk guide here.
- Download an OSHA combustible dust fact sheet. (pdf)
- Visit the OSHA combustible dust page.
- Review OSHA combustible resources in English and Spanish.
- Review OSHA advice for fighting combustible dust fires.
- Browse combustible dust safety signs.