Just because nothing's happened yet doesn't mean it's not about to. Are you still wondering if you have combustible dust? Still trying to convince upper management something needs to be tested BEFORE OSHA shows up, or worse, an accident occurs? Here's a sample list of items that can easily explode:
- foods - including candy, sugar, spice, starch, flour...
- metals including aluminum, chromium, iron, magnesium, zinc...
These materials are used in a wide range of industries and processes, such as agriculture, chemical manufacturing, pharmaceutical production, furniture, textiles, fossil fuel power generation, recycling operations, and metal working and processing which includes additive manufacturing and 3D printing. A wide variety of materials that can be explosible in dust form exist in many industries.
"Any combustible material can burn rapidly when in a finely divided form. If such a dust is suspended in air in the right concentration, under certain conditions, it can become explosible. Even materials that do not burn in larger pieces (such as aluminum or iron), given the proper conditions, can be explosible in dust form.
The force from such an explosion can cause employee deaths, injuries, and destruction of entire buildings. For example, 3 workers were killed in a 2010 titanium dust explosion in West Virginia, and 14 workers were killed in a 2008 sugar dust explosion in Georgia. The U.S. Chemical Safety and Hazard Investigation Board (CSB) identified 281 combustible dust incidents between 1980 and 2005 that led to the deaths of 119 workers, injured 718, and extensively damaged numerous industrial facilities."
The Canadian Centre for Occupational Health and Safety Combustible Dust Page is a terrific resource for defining an explosible dust (as "any finite solid particle, that upon ignition, is liable to catch fire or explode when dispersed in air"), identifying risks, and showing how dust explosions happen.
OH&S Occupational Health & Safety published an article "Combustible Dust Basics: How to Collect a Sample and What Does a Go/No-go Test Mean?" by yours truly in May 2014. A helpful guide if you are still deciding if you need to be concerned. (Yes, I googled and this kept coming up!)
So, you may already have a dust collector or are thinking you need one designed and this will solve combustibility issues? Dust explosions are a risk in many areas of a plant, but one of the most common locations is the dust collection system. Yes, many think they have dust combustibility covered simply by HAVING the collection system. Not even close. How do you know if your dust collection system complies? First, hire a process engineering firm that offers comprehensive assessment of your existing conditions or venting system. One that can also provide a particle analysis and testing, is a member of National Fire Protection Agency (NFPA) and other Authorities Having Jurisdicion (AHJs) affecting your plant is the starting place. Additionally, should be one that can review and analyze your conveying and storage system as well as the overall plant. Finally, one that can design and supply the specs for suppression and venting systems AND oversee the installation and implementation. There's the key! Purchasing and installing systems from a company that only "makes and/or installs" is asking for trouble. Where's the insurance and reassurance? Pointing fingers when something goes wrong is not wise. Few companies such as Spec Engineering provide this unique comprehensive type of service. Look for one that has you covered from assessment to inspection and everything in between.
Finally, know your regulations. Whether in the plant, airborne, shipped, etc., your risks of dust explosivity are great. Familiarize yourself with all things up-to-date regulations wise. There are three parties, other than stakeholders, that are primarily involved in the combustible dust rulemaking process:
Chemical Safety and Hazard Investigation Board (CSB)
Occupational Safety and Health Administration (OSHA)
National Fire Protection Association (NFPA)
Powder & Bulk Solids featured an overview of the long awaited NFPA 652 regulation in it's July 2014 issue which includes the importance of Process Hazards Analysis (PHAs) and Hazard Mitigation and Prevention .
Here is the full NFPA Dust list:
NFPA 61, Standard for the Prevention of Fires and Dust Explosions in Agricultural and Food Processing Facilities
NFPA 91, Standard for Exhaust Systems for Air Conveying of Vapors, Gases, Mists, and Noncombustible Particulate Solids
NFPA 120, Standard for Fire Prevention and Control in Coal Mines
NFPA 484, Standard for Combustible Metals
- NFPA 652, Combustible Dust Standard** (Newest)
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 Prevention of Sulfur Fires and Explosions
NFPA 664, Standard for the Prevention of Fires and Explosions in Wood
Processing and Woodworking Facilities
NFPA 850, Performance-Based Standard for Fire Protection for Light Water Reactor Electric Generating Plants
"A Lack of a Combustible Dust Standard is not stopping OSHA-
The “general duty clause” is Section 5(a)(1) of the Occupational Safety and Health Act of 1970.
Each employer shall furnish to each of his employees employment and a place of employment which are free from recognized hazards that are causing or are likely to cause death or serious physical harm to his employees.
The general duty clause is basically an all-encompassing regulation that OSHA uses if there is a perceived violation that is NOT covered by any other regulation. OSHA uses NFPA standards to justify citations."
The last acronym to know is ASTM International Testing Methods. This page will take you to all the Dust Tests available to every industry and type of dust to give you an idea of what is available via ASTM Standard Test Methods. Your professional partners can help you to navigate what tests will be needed based on your materials, conditions, equipment, processes and design. Basic testing is not expensive or daunting. Just remember, whatever you pay upfront now pales in comparison to any accident.