NFPA 660-2025 PDF

Full title and description

NFPA 660-2025 — Standard for Combustible Dusts and Particulate Solids. A consolidated NFPA standard that replaces and combines the fundamentals and industry-specific combustible-dust standards into a single document addressing hazard analysis, prevention, mitigation, and protection requirements for all combustible dusts and particulate solids.

Abstract

NFPA 660 (2025 edition) provides a single, unified set of requirements for identifying, evaluating, and controlling combustible dust and particulate-solid hazards across industries. It incorporates fundamental requirements (previously found in NFPA 652) in early chapters and places commodity- or industry-specific provisions into later chapters, thereby replacing several legacy NFPA combustible-dust standards. The standard includes updated definitions, requirements for Dust Hazard Analysis (DHA), operational readiness reviews, new evaluations for self-heating and chemical reactivity, clarifications on bonding/grounding and housekeeping, updated PPE language for flame-resistant garments, and other technical updates.

General information

• Status: Current / Active (approved and effective — consolidated combustible-dust standard now in force).
• Publication date: Approved/approved-as-standard and effective date December 6, 2024; published as the 2025 edition (printed edition metadata shows 2025).
• Publisher: National Fire Protection Association (NFPA).
• ICS / categories: Fire protection / safety (ICS classification typically falls under Protection against fire — e.g., ICS 13.220).
• Edition / version: 2025 edition (NFPA 660-2025).
• Number of pages: 387 pages (2025 printed edition metadata).

Scope

Sets minimum requirements for the recognition, evaluation, and control of fire, flash fire, and deflagration hazards associated with combustible dusts and particulate solids in industrial and commercial operations. The standard consolidates requirements previously distributed across NFPA 652, 61, 484, 654, 655, and 664 into one document, with general fundamentals in the initial chapters and industry/commodity-specific requirements organized into later chapters. It also references applicable NFPA protection-system standards (for example NFPA 68, NFPA 69) where equipment-level protection is addressed separately.

Key topics and requirements

• Requirement to perform a Dust Hazard Analysis (DHA) and criteria for who is qualified to conduct it.
• Fundamental prevention and mitigation measures (housekeeping, ignition-source control, process containment, ventilation).
• Operational readiness reviews and management-of-change provisions for processes handling combustible particulates.
• Requirements and clarifications for bonding and grounding of equipment and housekeeping tools.
• Updated definitions and new hazard evaluations (self-heating, thermal instability, water reactivity, chemical reactivity).
• Guidance and limits for flexible connectors, additive manufacturing considerations, and test standards for portable vacuum cleaners used with combustible metals.
• Updated PPE language addressing flame-resistant garments (FRG) and the level of protection required for flash-fire hazards versus structural fires.
• Organization of prior commodity-specific standards into dedicated chapters to simplify applicability and compliance.

Typical use and users

Used by EHS (environment, health & safety) professionals, plant and facility managers, process and mechanical engineers, designers of dust-handling and dust-control systems, authority having jurisdiction (AHJ) personnel, fire marshals, insurers, and manufacturers of industrial ventilation, dust-collection, and explosion-protection equipment. It is the primary NFPA reference for companies that manufacture, process, handle, or store combustible particulates.

Related standards

Consolidated from and related to: NFPA 652 (Fundamentals of Combustible Dust), NFPA 61 (Agriculture/food processing), NFPA 484 (Combustible Metals), NFPA 654 (General manufacturing/processing), NFPA 655 (Sulfur), and NFPA 664 (Woodworking). Equipment- and system-level protection standards that remain separately applicable include NFPA 68 (deflagration venting) and NFPA 69 (explosion prevention systems).

Keywords

combustible dust; particulate solids; dust hazard analysis; DHA; explosion prevention; deflagration; housekeeping; bonding and grounding; operational readiness; flame-resistant garments; NFPA 660; combustible-dust consolidation.

FAQ

Q: What is this standard?

A: NFPA 660-2025 is the National Fire Protection Association’s consolidated Standard for Combustible Dusts and Particulate Solids. It replaces several earlier NFPA combustible-dust standards to provide a single, comprehensive document addressing dust hazards and controls.

Q: What does it cover?

A: It covers requirements for recognition, evaluation (including Dust Hazard Analysis), prevention, mitigation, and protection against fires, flash fires, and deflagrations involving combustible dusts and particulate solids across industries. It also includes updated testing and equipment considerations and annex material to explain organization and applicability.

Q: Who typically uses it?

A: EHS teams, process and mechanical engineers, facility and plant managers, AHJs (including fire marshals), insurers, designers and installers of dust collection and explosion-protection systems, and manufacturers whose operations generate or handle combustible dusts.

Q: Is it current or superseded?

A: Current. NFPA 660-2025 was approved/accepted and became effective December 6, 2024; it supersedes and consolidates the earlier combustible-dust NFPA standards (listed above) and is the primary NFPA reference for combustible-dust hazards going forward.

Q: Is it part of a series?

A: It consolidates a series of combustible-dust standards into a single document; related NFPA standards addressing equipment protection (for example NFPA 68 and NFPA 69) remain separate and continue to be referenced where applicable.

Q: What are the key keywords?

A: Combustible dust, particulate solids, dust hazard analysis (DHA), explosion prevention, deflagration, bonding and grounding, housekeeping, operational readiness, flame-resistant garments.