NFPA 660 PDF

Highlights

The 2025 edition of NFPA 660, Standard for Combustible Dusts and Particulate Solids, features several updates, including:
Definitions for the terms transient releases, management of change, operational readiness review, and explosive- and propellant-actuated devices
Additional requirements for operational readiness reviews
New requirements to evaluate self heating, thermal instability, water reactivity, and chemical reactivity hazards
Additional language to address the level of protection provided by flame-resistant garments
Additional information about who is qualified to perform a DHA
Revisions to clarify the requirements for bonding and grounding of housekeeping equipment
Updates to resistance limits for flexible connectors and additive manufacturing requirements
New test standards for portable vacuum cleaners used with combustible metals

Table of Contents

NFPA® 660 Standard for Combustible Dusts and Particulate Solids 2025 Edition
Chapter 1 Administration
1.1 Scope.
1.2 Purpose.
1.3 Application.
1.4 Retroactivity.
1.5 Equivalency.
1.6 Conflicts.
1.7 Units and Formulas.
Chapter 2 Referenced Publications
2.1 General.
2.2 NFPA Publications.
2.3 Other Publications.
2.4 References for Extracts in Mandatory Sections.
Chapter 3 Definitions
3.1 General.
3.2 NFPA Official Definitions.
3.3 General Definitions.
Chapter 4 General Requirements
4.1 General.
4.2 Objectives.
Chapter 5 Hazard Identification
5.1 Responsibility.
5.2 Screening for Combustibility or Explosibility.
5.3 Self-Heating and Reactivity Hazards.
5.4 Combustibility and Explosibility Tests.
5.5 Sampling.
Chapter 6 Performance-Based Design Option
6.1 General Requirements.
6.2 Risk Component and Acceptability.
6.3 Performance Criteria.
6.4 Design Scenarios.
6.5 Evaluation of Proposed Design.
Chapter 7 Dust Hazards Analysis (DHA)
7.1 General Requirements.
7.2 Criteria.
7.3 Methodology.
Chapter 8 Management Systems
8.1 Retroactivity.
8.2 General.
8.3 Operating Procedures and Practices.
8.4 Housekeeping.
8.5 Hot Work.
8.6 Personal Protective Equipment (PPE).
8.7 Inspection, Testing, and Maintenance.
8.8 Training and Hazard Awareness.
8.9 Contractors.
8.10 Incident Investigation.
8.11 Management of Change.
8.12 Operational Readiness Review (ORR).
8.13 Documentation Retention.
8.14 Management Systems Review.
8.15 Employee Participation.
Chapter 9 Hazard Management: Mitigation and Prevention
9.1 Inherently Safer Designs. (Reserved)
9.2 Risk Assessment.
9.3 Building Design.
9.4 Equipment Design.
9.5 Dust Control.
9.6 Ignition Source Control.
9.7 Pyrophoric Dusts. (Reserved)
9.8 Explosion Prevention and Protection.
9.9 Fire Protection.
Chapter 10 Emergency Planning and Response
10.1 Retroactivity.
10.2 Emergency Response Plan.
10.3 Reserved.
Chapter 11 Reserved
Chapter 12 Reserved
Chapter 13 Reserved
Chapter 14 Reserved
Chapter 15 Reserved
Chapter 16 Reserved
Chapter 17 Reserved
Chapter 18 Reserved
Chapter 19 Reserved
Chapter 20 Reserved
Chapter 21 Agricultural and Food Processing
21.1 Administration.
21.2 Reserved.
21.3 Reserved.
21.4 General Requirements.
21.5 Hazard Identification.
21.6 Reserved.
21.7 Dust Hazards Analysis (DHA).
21.8 Management Systems.
21.9 Hazard Management: Mitigation and Prevention.
21.10 Emergency Planning and Response.
Chapter 22 Combustible Metals
22.1 Administration.
22.2 Reserved.
22.3 Reserved.
22.4 Reserved.
22.5 Hazard Identification.
22.6 Reserved.
22.7 Hazards Analysis.
22.8 Management Systems.
22.9 Hazard Management: Mitigation and Prevention.
22.10 Emergency Planning and Response.
22.11 Reserved.
22.12 Reserved.
22.13 Reserved.
22.14 Nanometal Powders
22.15 Additive Manufacturing
22.16 Alkali Metals.
22.17 Legacy Metals.
22.18 Other Metals.
22.19 Recycling and Waste Management Facilities
Chapter 23 Sulfur
23.1 Administration.
23.2 Reserved.
23.3 Reserved.
23.4 General Requirements.
23.5 Reserved.
23.6 Reserved.
23.7 Dust Hazards Analysis (DHA).
23.8 Management Systems.
23.9 Hazard Management: Mitigation and Prevention.
23.10 Reserved.
23.11 Handling of Liquid Sulfur at Normal Handling Temperatures.
23.12 Handling of Liquid Sulfur and Sulfur Vapor at Temperatures Above 309°F (154°C).
Chapter 24 Wood Processing and Woodworking Facilities
24.1 Administration.
24.2 Reserved.
24.3 Reserved.
24.4 Reserved.
24.5 Hazard Identification.
24.6 Reserved.
24.7 Process and Dust Hazards Analysis.
24.8 Management Systems.
24.9 Hazard Management: Mitigation and Prevention.
24.10 Emergency Planning and Response.
24.11 Thermal Oil Heating Systems.
24.12 Storage.
24.13 Special Considerations. (Reserved)
Chapter 25 Combustible Dusts and Particulate Solids Not Otherwise Specified
25.1 Administration.
25.2 Reserved.
25.3 Reserved.
25.4 Reserved.
25.5 Hazard Identification.
25.6 Reserved.
25.7 Dust Hazards Analysis (DHA).
25.8 Management Systems.
25.9 Hazard Management: Mitigation and Prevention
25.10 Reserved.
Annex A Explanatory Material
Annex B Dust Hazards Analysis — Example (CMD-FUN)
Annex C Accumulated Fugitive Dust (CMD-FUN)
Annex D Supplementary Information on Fire Protection (CMD-AGR)
Annex E Supplementary Information on Fumigation (CMD-AGR)
Annex F Employee Health and Safety (CMD-AGR)
Annex G Schematics of Typical Pneumatic Conveying Installations (CMD-AGR)
Annex H Checklist for Dust Hazards Analysis — Example for an Existing Facility (CMD-AGR)
Annex I Electrically Conductive Floors (CMD-CMM)
Annex J Supplementary Information on Magnesium (CMD-CMM)
Annex K Design for Dust Concentration Control in Ductwork (CMD-CMM)
Annex L Supplementary Information on Tantalum (CMD-CMM)
Annex M Supplementary Information on Titanium (CMD-CMM)
Annex N Supplementary Information on Zirconium (CMD-CMM)
Annex O Extinguishing Agents That Should Not Be Used on Lithium Fires (CMD-CMM)
Annex P Testing for Detailed Characterization of Explosive Behavior of Materials (CMD-CMM)
Annex Q Explosion Protection (CMD-HAP)
Annex R Informational Primer on Spark Detection and Extinguishing/Diversion Systems (CMD-HAP)
Annex S Dust Layer Characterization and Precautions (CMD-HAP)
Annex T Deflagration Propagation Isolation Methods (CMD-HAP)
Annex U Use of Water as Extinguishing Agent for Combustible Particulate Solids (CMD-HAP)
Annex V Guide for Computing Thermal Dose to Personnel from Flash Fires and Building Compartment Deflagrations(CMD-FUN)
Annex W Conveying System Isolation (CMD-WOO)
Annex X Automatic Water Spray Deluge Protection for Dryer Systems (CMD-WOO)
Annex Y Combustible Dust Test Data
Annex Z Informational References