NFPA 68:2023

Chapter 1 Administration 1.1 Scope. 1.2 Purpose. 1.3 Application. 1.4 Retroactivity. 1.5 Equivalency. 1.6 Conversion Factors. 1.7 Symbols. 1.8 Pressure. 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 Goal. 4.2 Objectives. 4.3 Compliance Options. Chapter 5 Performance-Based Design Option 5.1 General Requirements. 5.2 Performance Criteria. Chapter 6 Fundamentals of Venting of Deflagrations 6.1 Basic Concepts. 6.2 Mixtures. 6.3 Enclosure Design and Support. 6.4 Enclosure Length-to-Diameter Ratio and Vent Variables. 6.5 Vent Closure Operation. 6.6 Consequences of a Deflagration. 6.7 Effects of Vent Inertia. 6.8 Fireball Dimensions. 6.9 Effects of Vent Discharge Ducts. 6.10 Venting with Flame Arresting and Particulate Retention. Chapter 7 Venting Deflagrations of Gas Mixtures and Mists 7.1 Introduction. 7.2 Venting by Means of Low Inertia Vent Closures. 7.3 Partial Volume Effects. 7.4 Effects of Panel Inertia. 7.5 Effects of Vent Ducts. 7.6 Deflagration Venting of Enclosures Interconnected with Pipelines. Chapter 8 Venting of Deflagrations of Dusts and Hybrid Mixtures 8.1 Introduction. 8.2 Venting by Means of Low-Inertia Vent Closures. 8.3 Effects of Panel Inertia. 8.4 Effects of Partial Volume. 8.5 Effects of Vent Ducts. 8.6 Bins, Hoppers, and Silos. 8.7 Venting of Dust Collectors Using Bags, Filters, or Cartridges. 8.8 Bucket Elevators. 8.9 Venting Internal to a Building with Flame-Arresting and Particulate Retention Device. 8.10 Venting Silos or Other Storage Vessel Provided with Integral Bin Vents. 8.11 Deflagration Venting of Enclosures Interconnected with Pipelines.Chapter 9 Venting of Deflagrations of Gases and Dusts in Pipes and Ducts Operating at or Near Atmospheric Pressure 9.1 Introduction. 9.2 Design. 9.3 Multiple Deflagration Vents on a Pipe or Duct. Chapter 10 Details of Deflagration Vents and Vent Closures 10.1 Normally Open Vents. 10.2 Normally Closed Vents. 10.3 Types of Building or Room Vent Closures. 10.4 Restraints for Large Panels. 10.5 Equipment Vent Closures. Chapter 11 Inspection and Maintenance 11.1 General. 11.2 Design Parameters and Documentation. 11.3 Installation. 11.4 Inspection. 11.5 Procedures Following Vent Closure Actuation. 11.6 Vent Closure Design Parameters. 11.7 Inspection Reports. 11.8 Recordkeeping. 11.9 Management of Change. 11.10 Maintenance. 11.11 Employee Training.Annex A Explanatory Material Annex B Fundamentals of Deflagration Annex C Guidelines for Measuring Deflagration Parameters of Dusts Annex D Deflagration Characteristics of Select Flammable Gases Annex E Estimating Fundamental Burning Velocity Annex F Deflagration Characteristics of Select Combustible Dusts Annex G Calculation Method for Correction Factor Due to Increased Vent Panel Mass Annex H Research Reports and Supporting Documents Annex I Full and Partial Volume Gas Venting of a Building — Example Problem Annex J Effect of Dust Partial Volumes on Venting of Buildings — Example Problem Annex K Example Vent Sizing for Hydrogen Mixtures Annex L Bibliography Annex M Informational References

This standard applies to the design, location, installation, maintenance, and use of devices and systems that vent the combustion gases and pressures resulting from a de…a‐ gration within an enclosure so that structural and mechanical damage is minimized.