Consolidated Combustible Dust Standards Ready in 2025

NFPA 660 will combine fundamental combustible dust standards while breaking out the four standards specific to industries.

November 11, 2022

6 Min Read
A new NFPA 660 combustible dust code will consolidate four combustible dust standards into a single, unified code for consistency and ease.Image courtesy of SOPA Images Ltd/Alamy Stock Photo

Jean Thilmany, freelancer

A new National Fire Protection Association (NFPA) 660 combustible dust code will consolidate four NFPA combustible dust standards into a single, unified code for consistency and ease, said Jack Osborn, senior project engineer and combustible dust expert at Airdusco and participating member on six combustible dust standards committees.

The code is scheduled to be available in late 2025. Its first iteration is open for public input until Jan. 5, 2023. The currently used NFPA 652 Standard on the Fundamentals of Combustible Dust is “slipping cycle,” meaning it will no longer be updated—in favor of the new, consolidated NFPA 660.

The NFPA combustible dust document consolidation plan will bring together four “commodity specific” standards. They are:

  • NFPA 61, Prevention of Fires and Dust Explosions in Agricultural and Food Processing Facilities

  • NFPA 484, Combustible Metals

  • NFPA 654, Prevention of Fire and Dust Explosions from the Manufacturing, Processing, and Handling of Combustible Particulate Solids

  • NFPA 664, Prevention of Fires and Explosions in Wood Processing and Woodworking Facilities

The move to NFPA 660 will bring those separate standards into a central document. The first nine chapters of the new code will set forth the fundamental dust standards that apply to all four commodities. Each of the four standards will follow in individual chapters, said Laura Moreno, standards lead at NFPA.

“Hopefully this will make it easier for facility operates to figure out which requirements apply to them,” she said.

The standards are essential to manage the dust-related fire, flash fire, and explosion hazards in industries that use dust collection and handling equipment or that have processes that may generate combustible dust.

The current standard NFPA 652 is used by installers, contractors, engineers, facility managers, code enforcers, inspectors, and environmental health and safety (EHS) personnel for the information necessary to help handle combustible dust safely in any industry.

Moreno stressed that the individual commodity standards haven’t changed much in this initial document.

“At this stage of the process, we’re just focusing on aligning materials,” she added.

“For example, if section 8.4 in fundamentals section covers housekeeping then subsection 8.4 in each chapter will cover housekeeping to that commodity.”

The various NFPA technical committees are currently reviewing NFPA 652 to align standards and take out those that aren’t fundamental. As the process continues, there may be some differences of opinion between the various committees regarding what’s fundamental to them but not to other committees, Moreno added.

Even so, each industry and commodity-specific standards committee is tasked with developing the language that applies to their own chapter, Moreno said.

Eventually, there will be some common language that forms the basis of chapters one to nine. What isn’t fundamental will be broken out and geared towards specific industries in their respective chapters, she said.

In Case of Conflict

Facilities operators needn’t worry about which sections they should follow. NFPA 660 will make that clear and will resolve issues around conflicting requirements, Moreno said.

“It’s built into the standards that there will be conflicts between requirements,” she said, “For example, the fundamentals committee might require something in general for combustible dust, but the agriculture and food processing committee might say that’s not a requirement for them because it’s not a problem for grain dust.”

For that reason, each chapter begins with a conflict statement that says if an industry or community specific to that chapter has a requirement that differs from the basic in chapter one to nine, the requirements in the industry-specific chapter is allowed to be used instead.

“So, there may be conflicts between requirements, but there’s a way in this code to deal with them,” Moreno said.

At present, if there is a conflict between fundamental and industry-specific requirements, facility owners and operators can choose which one they want to follow. If their issue isn’t addressed in their commodity-specific standard, they follow the fundamental standards, Osborn said.


While the NFPA 652 Standard on the Fundamentals of Combustible Dust was adopted in 2016, there remained “big differences in how different technical committees were using 652,” Moreno said. “Some shortened their standards and returned to 652 for fundamentals. Others decided to pull everything from 652 into their docs so users would refer to one thing instead of going back and forth between 652 and their documents.”

In 2019, the NFPA Standards Council saw the need for a code that would address combustible dust standards across multiple industries, Moreno said. The council oversees the NFPA codes and standards development activities, administers the rules and regulations, and acts as an appeals body.

While the council coordinates the code-development process, the day-to-day work is done by various committees. For instance, a technical committee gets “deep into the document to vote on what requirements should be included where and what they should apply to,” Moreno said.

In early 2020, the correlating council that oversees dust documents began to work on a standard that would apply to all combustible dust.

The council and the various technical committees soon decided to maintain the integrity of the commodity-specific standards “because there are just too many differences between metals and wood and food and chemicals,” Osborn said. “There are just major differences you can’t cover in one standard without having those chapters in there.”

What Happens Next?

The date for the release of NFPA 660 has been set back about a year due to COVID and other factors. The technical committees have put together a first draft, which the NFPA Standards Council has put forward for public review. Moreno said. The draft is open for input from all members of the public until Jan. 5, 2024.

The technical committees will then review the input and potentially make changes based on that feedback.

“Likely, they may add something new or change some working,” Moreno said. “Then they’ll take action on them.”

Once they’ve approved the new draft, it goes back out for public review. This second review date is expected to be open for comments for six to eight weeks in late 2024.

After public review closes, the draft process repeats itself within the technical committees. The code will again be up for public review. But this time, members of the public must submit motion for changes to be heard at the technical committee meeting in the summer of 2025.

“If we don’t receive any notices, the document will formally get issues in early 2025,” Moreno said. “But if we do receive notices … well, that’s one more bite of the apple.”

She encourages anyone who wants to submit comment to do so, because it’s a vital way to provide feedback on the code.

“If something is confusing or hard to apply, please let the technical committees know,” Moreno said. “That’s how the committees make the standards better for the people who use them.”

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