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NFPA 68, Standard on Explosion Protection by Deflagration Venting

2023 NFPA 68 Standard - Current Edition
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  • Description

    Help make industrial occupancies safer with the most current requirements for fire and explosion protection by deflagration venting.

    NFPA® 68, Standard on Explosion Protection by Deflagration Venting, 2023 edition, reflects updated technology, evolving fire safety practices, and the knowledge and experience of experts in the field. The revised standard offers the latest information on the design, location, installation, maintenance, and use of devices and systems that vent the combustion gases and pressures resulting from a deflagration within an enclosure to minimize structural and mechanical damage.

    Notable changes include:

    • Requirements combined for fireball and hazard distance requirements for gases and dust and moved into Chapter 6 for consistency in application
    • Revised partial volume calculations for both gases and dust to account for solid objects reducing the open-air volume available for mixing and for possible dust concentrations below the worst-case concentrations
    • Updated fundamental burning velocity values in the annex based on currently available data
    • Added an annex on vent sizing for hydrogen mixture
  • Table of Contents (2023 Current Edition)

    NFPA® 68 Standard on Explosion Protection by Deflagration Venting, 2023 Edition

    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
  • Prior Editions

    2018 Edition

    Implement the latest best practices for industrial fire protection and fire safety with the most advanced edition of NFPA 68.

    Reflecting changes in technology, recent fire experience, and current fire safety practices, NFPA 68, Standard on Explosion Protection by Deflagration Venting applies to the design, location, installation, maintenance, and use of devices and systems that vent the combustion gases and pressures resulting from a deflagration within an enclosure so that structural and mechanical damage is minimized.

    This flexible Standard includes a performance-based option, including self-contained chapters supporting the performance-based aspect.

    Major technical changes help you apply requirements and determine the right protocols. In this edition:

    • New requirements are included to adjust the KSt values for certain metal dusts if the KSt value was obtained in a vessel smaller than 1 m3.
    • An added equation helps you determine the hydraulic diameter for rectangular enclosures.
    • A reorganized chapter on venting gas mixture and mist deflagrations clarifies the order and applicability of the various adjustments and corrections to required vent area. A new annex shows you how to implement the equations and calculation procedures, including partial volume effects.
    • New requirements for determining Pmax, that replace requirements for determining KG, with revised equations for determining the turbulent flame enhancement factor.
    • A reorganized chapter on venting dust and hybrid mixture deflagrations provides rules in the order they're applied in the field.
    • A revised equation helps you determine vent area for elevated or subatmospheric pressure, with an example calculation added to the annex.
    • Revised method of determining enclosure volume for dust collectors helps users calculate safe vent areas.
    • Requirements for the use of plastic buckets in bucket elevators, previously in the annex, are now in the body of the Standard.

    Base your industrial fire protection strategies on the latest edition of NFPA 68. (Print, 104 pp., 2018)

     

    2013 Edition

    NFPA 68 includes the new best practices for Industrial fire protection and fire safety.

    Updated based on technology changes, fire experience, and the latest fire safety practices, NFPA 68 Standard on Explosion Protection by Deflagration Venting applies to the design, location, installation, maintenance, and use of devices and systems that vent the combustion gases and pressures resulting from a deflagration within an enclosure so that structural and mechanical damage is minimized.

    The Standard includes a performance-based option, including self-contained chapters supporting the performance-based aspect.

    Important changes in the 2013 edition include:

    • Updated requirements for pressure vent manifolds
    • Updated method and equations for venting of gas mixtures
    • Added equations for venting of enclosures with initial pressures below atmospheric
    • A new section on bucket elevators
    • A new annex chapter on estimating fundamental burning velocities

    Base your industrial fire protection strategies on the latest edition of NFPA 68. (Softbound, 80 pp., 2013)

     

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