NFPA 69-2014 Standard on Explosion Prevention Systems (Effective Date 12 2 2013 ALERT THIS STANDARD HAS BEEN MODIFIED BY A TIA OR ERRATA).pdf

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11、NING NFPASTANDARDS Copyright 2013 National Fire Protection Association. All Rights Reserved.NFPA69Standard onExplosion Prevention Systems2014 EditionThis edition of NFPA 69, Standard on Explosion Prevention Systems, was prepared by theTechnical Committee on Explosion Protection Systems. It was issue

12、d by the Standards Coun-cil on November 12, 2013, with an effective date of December 2, 2013, and supersedes allprevious editions.This document has been amended by one or more Tentative Interim Amendments (TIAs)and/or Errata. See “Codes for high-strength enclo-sures the enclosure design pressure suf

13、ficient to resist Pred.68, 20133.3.14 Explosion. The bursting or rupture of an enclosure ora container due to the development of internal pressure froma deflagration.697DEFINITIONS2014 Edition3.3.15 Fast-Acting Valve. A valve that closes a path of deflagra-tion propagation in a pipe or duct in respo

14、nse to upstreamdetection of a deflagration.3.3.16* Flame Arrester. A device that prevents the transmis-sion of a flame through a flammable gas/air mixture byquenching the flame on the surfaces of an array of small pas-sages through which the flame must pass.3.3.17 Flame Front Diverter. A device that

15、 opens in responseto the pressure wave preceding the flame front of the deflagra-tion, thereby venting the pressure wave and flame front.3.3.18 Flame Speed. The speed of a flame front relative to afixed reference point. 68, 20133.3.19*FlammableLimits. The minimum and maximum con-centrations of a com

16、bustible material in a homogeneous mix-ture with a gaseous oxidizer that will propagate a flame.3.3.19.1 Lower Flammable Limit (LFL). The lowest con-centration of a combustible substance in an oxidizing me-dium that will propagate a flame.3.3.19.2 Upper Flammable Limit (UFL). The highest con-centrat

17、ion of a combustible substance in a gaseous oxidizerthat will propagate a flame. 68, 20133.3.20 Flammable Range. The range of concentrations be-tween the lower and upper flammable limits. 68, 20133.3.21 Gas. The state of matter characterized by completemolecular mobility and unlimited expansion; use

18、d synony-mously with the term vapor.68, 20133.3.21.1 Inert Gas. A gas that is noncombustible and non-reactive.3.3.21.2 Purge Gas. An inert or a combustible gas that iscontinuously or intermittently added to a system to renderthe atmosphere nonignitible.3.3.22*HybridMixture. An explosible heterogeneo

19、us mixture,comprising gas with suspended solid or liquid particulates, inwhich the total flammable gas concentration is 10 percent ofthe lower flammable limit (LFL) and the total suspended par-ticulate concentration is 10 percent of the minimum explosibleconcentration (MEC). 68, 20133.3.23 Inerting.

20、 A technique by which a combustible mixtureis rendered nonignitible by adding an inert gas or a noncom-bustible dust. (See also 3.3.1, Blanketing.)3.3.24* Isolation. A means of preventing certain stream prop-erties from being conveyed past a predefined point.3.3.24.1 Chemical Isolation. A means of p

21、reventing flamefront and ignition from being conveyed past a predeter-mined point by injection of a chemical suppressant.3.3.24.2 Deflagration Isolation. A method employing equip-ment and procedures that interrupts the propagation of adeflagration flame front past a predetermined point.3.3.24.3 Flow

22、 Isolation. A method employing equipmentand procedures that interrupts flow and prevents pressurerise beyond a predetermined point.3.3.24.4 Ignition Source Isolation. A method employingequipment and procedures that interrupts the propaga-tion of an igniting medium past a predetermined point.3.3.25*

23、Limiting Oxidant Concentration (LOC). The concen-tration of oxidant in a fuel-oxidant-diluent mixture belowwhich a deflagration cannot occur under specified conditions.3.3.26 Liquid Seal. A device that prevents the passage of flameby passing the gas mixture through a noncombustible liquid.3.3.27 Max

24、imum Experimental Safe Gap (MESG). The maxi-mum clearance between two parallel metal surfaces that hasbeen found, under specified test conditions, to prevent anexplosion in a test chamber from being propagated to a sec-ondary chamber containing the same gas or vapor at the sameconcentration. 497, 20

25、123.3.28 Maximum Pressure (Pmax). The maximum pressuredeveloped in a contained deflagration of an optimum mix-ture. 68, 20133.3.29 Mist. A dispersion of fine liquid droplets in a gaseousmedium. 68, 20133.3.30 Oxidant. Any gaseous material that can react with a fuel(either gas, dust, or mist) to prod

26、uce combustion. 68, 20133.3.31 Padding. See 3.3.1.3.3.32 Pressure Piling. A condition during deflagration inwhich pressure increases in the unreacted medium ahead ofthe propagating combustion zone.3.3.33 Qualified Person. A person who possesses a recog-nized degree, certificate, professional standin

27、g, or skill andwho, by knowledge, training, and experience, has demon-strated the ability to deal with problems related to the subjectmatter, the work, or the project.3.3.34* Reduced Pressure (Pred). The maximum pressure de-veloped in a vented enclosure during a vented deflagration.68, 20133.3.35* S

28、elf-Decomposing Mixtures. Materials or mixtures ca-pable of propagating a flame in the absence of oxidant.3.3.36 Spark Extinguishing System. An extinguishing systemin which the radiant energy of a spark or an ember is detectedand the spark or ember is quenched.3.3.37 Suppressant. The chemical agent

29、used in a deflagra-tion suppression system to extinguish the deflagration.3.3.38 System Acceptance. A series of actions to verify instal-lation, operation, and integration of the protection system inaccordance with the basis of design, as well as training, valida-tion testing, documentation, and arm

30、ing of the system.3.3.39 TroubleSignal. A signal that results from the detectionof a trouble condition. 72, 20133.3.39.1 Trouble Condition. An abnormal condition in asystem due to a fault. 72, 20133.3.40 Vapor. See 3.3.21.3.3.41 Ventilation. The changing of air within a compart-ment by natural or me

31、chanical means. 302, 2010Chapter 4 General Requirements4.1 Goal. The goal of this standard shall be to provide effec-tive deflagration prevention and control for enclosures wherethere is the potential for a deflagration.698 EXPLOSION PREVENTION SYSTEMS2014 Edition4.2 Objectives.4.2.1 Life Safety.4.2

32、1.1 Deflagration prevention and control for occupied en-closures shall prevent the structural failure of the enclosureand minimize injury to personnel in adjacent areas outside ofthe enclosure.4.2.1.2 Deflagration prevention and control for unoccupiedenclosures shall prevent the rupture of the encl

33、osure.4.2.1.3 Deflagration prevention and control shall be ar-ranged to avoid injury to personnel.4.2.2 Property Protection.4.2.2.1 Deflagration prevention and control systems shall bedesigned to limit damage of the protected enclosure.4.2.2.2 Deflagration prevention and control systems shall bearra

34、nged to avoid ignition of adjacent property.4.2.2.3 Deflagration prevention and control systems shall bedesigned to avoid damage to adjacent property.4.2.2.4 Deflagration prevention and control shall be de-signed to avoid projectile damage to adjacent property.4.2.3 Hazard Analysis.4.2.3.1 The desig

35、n basis deflagration hazard scenario shall beidentified and documented.4.2.3.2 A documented risk evaluation acceptable to the au-thority having jurisdiction shall be permitted to be conductedto determine the level of protection to be provided.4.3 Compliance Options.4.3.1 Options. Deflagration protec

36、tion and control meetingthe goals and objectives of Sections 4.1 and 4.2 shall be pro-vided in accordance with either of the following:(1) The performance-based provisions of 4.3.2(2) The prescriptive-based provisions of 4.3.34.3.2 Performance-Based Design. A performance-based de-sign shall be in ac

37、cordance with Chapter 5 of this standard.4.3.3 Prescriptive-Based Design. A prescriptive-based designshall be in accordance with Chapters 6 through 15 of thisstandard.Chapter 5 Performance-Based Design Option5.1 General Requirements.5.1.1 Qualifications. The performance-based design shall beprepared

38、 by a person with qualifications acceptable to the au-thority having jurisdiction.5.1.2 Design Documentation. The design methodology anddata sources shall be documented and maintained for the lifeof the protected enclosure.5.1.3 Management of Change.5.1.3.1 To continue meeting the performance goals

39、and ob-jectives of this standard, the design features required for eachprevention and control system shall be maintained for the lifeof the protected enclosure.5.1.3.2 Any changes to the process shall require review of thedesign basis for each affected prevention and control systemprior to implement

40、ation of the change.5.1.3.3 Any changes to the design features shall requireapproval of the authority having jurisdiction prior to theactual change.5.2 Performance Criteria.5.2.1 Prevention and control system design shall be based onthe documented hazard scenario.5.2.2 Prevention and control systems

41、 shall limit the reducedpressure (Pred) within an enclosure to meet the objectives in4.2.1.1 and 4.2.1.2.5.2.3 Deflagration Prevention and Control.5.2.3.1 Combustible material outside the enclosure shall notattain their ignition temperature from flame or hot gases.5.2.3.2 Prevention and control syst

42、ems shall limit the risk ofdamage to exposed structures.5.2.3.3 Prevention and control systems shall not expose per-sonnel to flame, hot gases, hot particles, toxic materials, orprojectiles.5.2.3.4 Prevention and control systems shall limit the risk offlame spread from vessel to vessel via interconn

43、ected ducts.5.2.4 Inspection and Maintenance.5.2.4.1 Prevention and control systems shall be regularly in-spected and maintained to confirm the ability to perform asdesigned.5.2.4.1.1 If no guidance is given from the performance-baseddesign documents, the requirements of Chapter 15 of thisstandard s

44、hall apply.5.2.4.2 Inspection and maintenance shall be documentedand retained for at least 1 year or the last three inspections.Chapter 6 General Prescriptive Requirements6.1* Methods. The methods recognized in this standard shallbe grouped based on the prevention of combustion or on theprevention o

45、r limitation of damage after combustion occurs.6.1.1 Methods Based on the Prevention of Combustion. Thefollowing shall be considered methods based on preventingcombustion:(1) Oxidant concentration reduction(2) Combustible concentration reduction6.1.2 MethodsBasedonthePreventionorLimitationofDam-age.

46、 The following shall be considered methods based on pre-venting or limiting damage:(1) Predeflagration detection and ignition control systems(2) Deflagration suppression(3) Isolation methods(4) Deflagration pressure containment6.2 Limitations. The limitations specific to each method shallbe consider

47、ed and are specified in the corresponding chapterfor each method.699GENERAL PRESCRIPTIVE REQUIREMENTS2014 Edition6.3 Factors to Be Considered. The following factors shall beconsidered in the selection of one of the methods and thedesign of the system:(1) Effectiveness of each method(2) Reliability o

48、f the system(3) Personnel hazards inherent in each method6.3.1 The reliability of the system chosen shall be assessedusing the following factors:(1) System design basis(2) Possibility of electrical and mechanical malfunction(3) Dependence on sophisticated activating systems(4) Need for special insta

49、llation, training, operating, testing,and maintenance procedures(5) Further limitations as presented in each chapter6.3.2 In general, explosion prevention systems shall be used toprotect processing, storage, and materials-handling equipment.6.3.3 When explosion prevention techniques are appliedto rooms, buildings, or other enclosures where personnelare present, consideration shall be given to the safety of thepersonnel.6.3.4 When using the techniques of Chapters 10, 11, 12, or13, or of NFPA 68, Standard on Explosion Protection by Deflagra-tion Venting,