Navigating Combustible Dust
“Proper housekeeping is a powerful and essential line of defense against many types of workplace hazards, and combustible dust is no exception. NFPA 652 recommends cleaning methods, such as vacuuming, but also outlines specific design requirements to ensure the equipment can meet the demands of collecting combustible dust. In the absence of a formal OSHA rule, NFPA 652 is vital to guiding our manufacturing customers on how to identify, measure and most importantly, choose the proper industrial vacuum to safely mitigate their combustible dust risk.” Nilfisk, 800-989-2235, www.nilfisk.us
Why Standard was Created
NFPA 652: Standard on the Fundamentals of Combustible Dust, 2016 edition, became effective Sept. 2015. This standard was created to promote and define hazard analysis, awareness, management and mitigation. The standard also issues a new term, Dust Hazard Analysis (DHA), to differentiate this analysis from the more complex forms of process hazard analysis methods currently found in industry. NFPA 652 is the starting point for this analysis. It will guide you, step by step, in identifying hazards and what to do next. If a company has processes that create dust or use powders, then it has a responsibility to determine if a combustible dust hazard exists.
The NFPA standards have required a process hazard analysis since 2005. NFPA 652 takes this requirement further by making this requirement retroactive to existing installations, with a deadline. A DHA is now required for new installations and upgrades to existing installations. The standard allows three years to complete this DHA. To illustrate the importance of this hazard analysis, many OSHA citations regarding combustible dust hazards list the lack of a hazard analysis at the top of the citation.
Combustible dusts are created during the transportation, handling, processing, polishing and grinding of the materials. Abrasive blasting, crushing, cutting and screening dry materials can also create dust.
Combustible dust is any fine material that can catch fire and explode when mixed with air. OSHA defines combustible dust as “…a solid material composed of distinct particles or pieces, regardless of size, shape or chemical composition, which presents a fire or deflagration hazard when suspended in air or some other oxidizing medium over a range of concentrations.”
This does not always mean the types of material normally considered either combustible or dangerous. It can include metal dust, wood dust, plastic or rubber dust, coal dust, biosolids, dust from certain textiles—even organic dust, like flour, sugar, paper, soap and dried blood.
Key Compliance Requirements
The purpose of a dust-collection system is to remove and isolate dust away from people who can inhale it and process areas where it could accumulate and become a deflagration hazard. The DHA will identify the following conditions that may exist external or internal to the system that contribute to a fire or deflagration hazard:
- Presence of oxygen: Air is the oxidant
- Presence of fuel: Combustible dust whereever it is found, including floors, elevated surfaces, inside ducts, and inside process enclosures and machines
- Dispersion of fuel: includes pulse cleaning inside dust collector; use of compressed air for cleaning; and events that can dislodge dust from elevated surfaces
- Ignition sources: Sparks, electrical shorts, hot work, electrostatic discharge, flames, rotating equipment, hot surfaces
- Containment locations: inside pipes; inside dust collectors; and inside any process enclosure or machine.
Because so many different types of workplaces might contain potential combustible dust risks, it’s essential to conduct a thorough risk assessment. Failing to comply with this standard can leave you open to serious fines and even more serious injuries, if an incident occurs.
- OSHA offers a lengthy list of materials that could produce combustible dust: https://bit.ly/1Lni5C7
- Become familiar with NFPA 652: Standard on the Fundamentals of Combustible Dust. https://bit.ly/2KD03Po. It provides basic principles and requirements for identifying and managing fire and explosion hazards from combustible dust.
- OSHA looks to this standard for guidance when it comes to best practices for preventing combustible dust fires and explosions. Those who don’t take the necessary steps to protect workers can be fined for violations under 18 different standards as part of OSHA’s Combustible Dust National Emphasis Program. https://bit.ly/2Rd1Eh8. This includes the General Duty Clause and 29 CFR 1910.22, the main housekeeping standard.
- For more an in-depth discussion of combustible dust, see the article titled “How to Prevent Combustible Dust Incidents in the Workplace” in WMHS’s November 2018 issue: https://bit.ly/2zsbRPM
Addressing Dust Challenges for Food Packaging
Dust can often be created during packaging, as finished products are moved by conveyor or during the box- or bag-filling process. The “puffs” of compressed air used during the bag-filling process can generate little puffs of dust while filling packages. This can cause an accumulation of dust over time, if not addressed properly, which can also create several challenges during the packaging process, including:
- Cross-contamination: Packaging lines for multiple products are often located in the same facility, creating a cross-contamination concern if fugitive dust is allowed to escape.
- Nuisance dust/aesthetics: Dust that settles on or in packaging is unappealing to consumers of packaged food products.
- Microbial growth: Dust that is allowed to settle on surfaces in the packaging facility or in between packaging layers provides a medium for microbial growth.
- Combustion risk: Food processing dusts—including flours, powdered milk, corn starch, wheat starch, sugar, tapioca, whey, cocoa powder and many spices—are highly combustible.
To address the challenges, food packaging operations must look at the whole process, including needs analysis, system design and engineering, collector and ductwork installation, filter selection, HVAC system integration, startup and commissioning, and aftercare and service. Calling the experts to help ensure your operations remains NFPA 652-compliant.
–Packaging Technology Today