NFPA 660 Guide

NFPA 660: the combustible dust standard, chapter by chapter.

NFPA 660 is the one NFPA standard for combustible dusts and particulate solids. It consolidated six separate standards: NFPA 61, 484, 652, 654, 655, and 664. If your facility makes, handles, or collects a dust that can burn, this is the standard your dust hazard analysis (DHA) should be written to.

How NFPA 660 is organized

You read NFPA 660 in two parts. The fundamentals in Chapters 1 through 10 always apply. Then you add the chapter for your material.

Chapter	What it covers	Consolidated from
1 to 10	Fundamentals for every facility: administration, definitions, general requirements, hazard identification, the performance-based option, the DHA (Chapter 7), management systems, hazard management, and emergency planning	NFPA 652
21	Agricultural and food processing	NFPA 61
22	Combustible metals	NFPA 484
23	Sulfur	NFPA 655
24	Wood processing and woodworking	NFPA 664
25	Combustible dusts and particulate solids not otherwise specified	NFPA 654

Chapters 11 through 20 are reserved for future use. NFPA 68 (deflagration venting) and NFPA 69 (explosion prevention systems) were not consolidated. They remain separate standards that NFPA 660 references.

What NFPA 660 asks of your facility

• A DHA for any operation that handles combustible dust, regardless of size, including existing facilities. See what a DHA is and whether your facility needs one.
• A qualified person performs or leads it. NFPA 660 is clear that a credential such as PE, CSP, or CIH does not, by itself, make someone qualified. See who counts as a qualified person.
• A review at least every five years and whenever your process changes. See DHA revalidation.
• Management systems: housekeeping, hot work, training, management of change, and incident investigation. NFPA 660 does not set one universal housekeeping depth. See housekeeping under NFPA 660.
• Hazard management based on what your DHA finds, from equipment protection to venting, isolation, and suppression.

If your DHA was written to the old standards

NFPA 660 ties DHA reviews to two triggers: at least every five years, and whenever your process changes.

• When your next review is due, by either trigger, write it to NFPA 660.
• Old section references to NFPA 652, 61, 484, 654, 655, or 664 will not match NFPA 660, so updating them belongs in that review.
• No DHA yet: start with one written to NFPA 660.

For the full story of the consolidation, see NFPA 660 explained. For how OSHA connects to it, see is a DHA required by OSHA.

Who this guide is not for

This is not the text of the standard. NFPA publishes NFPA 660, and you can get it from NFPA directly. This guide is for the plant manager, EHS lead, or owner who needs to know what NFPA 660 means for their facility and their DHA.

Questions about NFPA 660

What is NFPA 660?

NFPA 660 is the Standard for Combustible Dusts and Particulate Solids. It consolidated NFPA 61, 484, 652, 654, 655, and 664 into one document.

What standards did NFPA 660 replace?

NFPA 652 (fundamentals), NFPA 61 (agricultural and food), NFPA 484 (combustible metals), NFPA 654 (particulate solids not otherwise specified), NFPA 655 (sulfur), and NFPA 664 (wood).

Where is the DHA requirement in NFPA 660?

Chapter 7 covers the dust hazard analysis.

Did NFPA 660 replace NFPA 68 and NFPA 69?

No. NFPA 68 and NFPA 69 remain separate standards. NFPA 660 references them.

Which NFPA 660 chapter applies to my facility?

Chapters 1 through 10 apply to everyone. Then food and agriculture add Chapter 21, metals Chapter 22, sulfur Chapter 23, wood Chapter 24, and everything else Chapter 25. A facility with several materials applies each chapter that fits.

How often does a DHA need to be reviewed under NFPA 660?

At least every five years, and whenever your process changes.