NFPA 499-2017 Recommended Practice for the Classification of Combustible Dusts and of Hazardous (Classified) Locations for Electrical Installations in Chemical Process Areas (Effec.pdf

1、 NFPA 499 Recommended Practice for the Classification of Combustible Dusts and of Hazardous (Classified) Locations for Electrical Installations in Chemical Process Areas 2017IMPORTANT NOTICES AND DISCLAIMERS CONCERNING NFPA DOCUMENTS NOTICE AND DISCLAIMER OF LIABILITY CONCERNING THE USE OF NFPA DOCU

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29、ndards can be viewed at no cost at www.nfpa.org/freeaccess.499-1 NFPA and National Fire Protection Association are registered trademarks of the National Fire Protection Association, Quincy, Massachusetts 02169. Copyright 2016 National Fire Protection Association . All Rights Reserved. NFPA 499 Recom

30、mended Practice for the Classication of Combustible Dusts and of Hazardous (Classied) Locations for Electrical Installations in Chemical Process Areas 2017 Edition This edition of NFPA 499, Recommended Practice for the Classication of Combustible Dusts and of Hazardous (Classied) Locations for Elect

31、rical Installations in Chemical Process Areas, was prepared by the Technical Committee on Electrical Equipment in Chemical Atmospheres. It was issued by the Standards Council on May 13, 2016, with an effective date of June 2, 2016, and supersedes all previous editions. This edition of NFPA 499 was a

32、pproved as an American National Standard on June 2, 2016. Origin and Development of NFPA 499 The Technical Committee on Electrical Equipment in Chemical Atmospheres began the development of NFPA 497B, Recommended Practice for the Classication of Class II Hazardous (Classied) Locations for Electrical

33、 Installations in Chemical Process Areas, in 1989. The technical committee based the diagrams in this document on various NFPA codes and standards and on accepted practices in the chemical process industries. The rst edition of this recommended practice was adopted by the NFPA membership at the 1990

34、 November Technical Meeting, which became the 1991 edition. In 1993, the technical committee combined the information on group classications of dusts located in NFPA 497M, Classication of Gases, Vapors, and Dusts for Electrical Equipment in Hazardous (Classied) Locations, and the information in NFPA

35、 497B into an expanded version and renamed the document Recommended Practice for the Classication of Combustible Dusts and of Hazardous (Classied) Locations for Electrical Installations in Chemical Process Areas, 1997. The table information on dusts was expanded to include CAS numbers for clarity an

36、d user friendliness. In 2001, the technical committee entered NFPA 499 into the November 2003 revision cycle. The 2004 edition was signicantly revised and reorganized to comply with the 2003 NFPA Manual of Style for technical committee documents. The organizational and editorial changes enhanced the

37、 usability of this recommended practice. In addition, editorial changes were made to harmonize the text with the requirements of NFPA 70, National Electrical Code. The 2008 edition of NFPA 499 was the culmination of a revision cycle that began with the document being entered into cycle in January 20

38、06. NFPA 499 is closely tied to the electrical installation requirements for hazardous (classied) locations contained in NFPA 70. To ensure correlation with revisions to the 2008 edition of NFPA 70, the Technical Committee on Electrical Equipment in Chemical Atmospheres was granted permission by the

39、 NFPA Standards Council to enter into a three-year (Fall 2007) revision cycle. Signicant revisions to the 2008 edition included the following: (1) Changes to the scope to specify that explosives, pyrotechnics, and blasting agents have unique hazards not addressed by the document (2) Revisions to Tab

40、le 4.5.2 on composition and ignition temperature of combustible materials to correlate with information contained in other industry documentsCLASSIFICATION OF COMBUSTIBLE DUSTS AND OF HAZARDOUS (CLASSIFIED) LOCATIONS FOR ELECTRICAL INSTALLATIONS 499-2 2017 Edition The 2013 edition was a complete rev

41、ision to update references and extracted text. As a result of updating ASTM references, the 2010 edition of ASTM E1226, Standard Test Method for Explosibility of Dust Clouds, was incorporated, which eliminated the use of the ignition sensitivity (IS) and explosion severity (ES) criteria in NFPA 499.

42、 Those criteria were eliminated because ASTM E1226 now has a “Go/No-Go” criterion that assesses the combustibility of a dust. Also, a new Chapter 4, on general criteria for combustible dusts and their ignition characteristics, was added. The 2017 edition has been revised to update consistency betwee

43、n the gures and text regarding a transitional classied location around doorways. Other revisions have been made that correlate with revisions to the 2017 edition of NFPA 70. There also are extensive revisions that add the zone classication system from NFPA 70.COMMITTEE PERSONNEL 499-3 2017 Edition T

44、echnical Committee on Electrical Equipment in Chemical Atmospheres William T. Fiske, Chair Intertek Testing Services, NY RT Donald W. Ankele, UL LLC, IL RT Babanna Biradar, Bechtel India Pvt Ltd, India SE Ronald M. Brown, PPG Industries, Inc., PA U Jonathan L. Cadd, Electrical Systems and Instrument

45、ation, Inc., TX M John H. Cawthon, State of Alaska Division of Fire (2) making recommendations for the prevention of res and explosions through the use of continuously purged, pressurized, explosion-proof, or dust-ignition-proof electrical equipment where installed in such chemical atmospheres.CLASS

46、IFICATION OF COMBUSTIBLE DUSTS AND OF HAZARDOUS (CLASSIFIED) LOCATIONS FOR ELECTRICAL INSTALLATIONS 499-4 2017 Edition Contents Chapter 1 Administration 499 5 1.1 Scope. . 499 5 1.2 Purpose. . 499 5 1.3 Application. 499 5 1.4 Relationship to NFPA Codes and Standards. . 499 5 Chapter 2 Referenced Pub

47、lications 499 6 2.1 General. 499 6 2.2 NFPA Publications. 499 6 2.3 Other Publications. . 499 6 2.4 References for Extracts in Recommendations Sections. . 499 6 Chapter 3 Denitions . 499 6 3.1 General. 499 6 3.2 NFPA Ofcial Denitions. 499 6 3.3 General Denitions. 499 6 Chapter 4 Combustible Dusts 49

48、9 7 4.1 General. 499 7 4.2 Combustible Dust Testing. 499 7 4.3 Additional Potential Combustible Dust Hazards. 499 8 4.4 Classication of Combustible Dusts. 499 8 4.5 Hybrid Mixtures. 499 9 4.6 Electrostatic Discharges. . 499 9 4.7 Ignition Criteria. 499 9 Chapter 5 National Electrical Code (NEC) Crit

49、eria . 499 9 5.1 Classication of Class II Hazardous Locations and National Electrical Code (NEC) Criteria. 499 9 5.2 Classication of Combustible Dusts. 499 10 Chapter 6 Classication of Combustible Dust Locations . 499 16 6.1 General. 499 16 6.2 Conditions Necessary for Ignition of Combustible Dust. . 499 16 6.3 Class II, Division 1 or Zone 20/Zone 21 Classied Locations. . 499 16 6.4 Combustible Dust, Class II, Division 2 or Zone 22, Classied Locations. 499 17 6.5 Unclassied Locations. 499 17 6.6 Pr