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Technical Committee on Electrical Equipment in Chemical Atmospheres
Date: August 6, 2015 To: Technical Committee on Electrical Equipment in Chemical Atmospheres From: Eric Nette, P.E. Staff Liaison/Engineer Re: Agenda Package – NFPA 496/497/499 A2016 Second Draft Meeting – Sept. 30-Oct. 1, 2015
Enclosed is the agenda package for the Sept. 30-Oct. 1, 2015 meeting for the NFPA 496/497/499 Second Draft Meeting. Please ensure that you have reviewed the public input and the other agenda items in advance to prepare for discussion. The agenda and public comments will be posted on the document information pages (www.nfpa.org/496next). Some items to have available during the meeting include:
Agenda package with public comments
A copy of NFPA 496/497/499 (visit the NFPA 496/497/499 Document information pages for your free committee copy)
Any previous copies of the technical committees standard
A laptop
Optional items that are sometimes useful include:
Review of NFPA’s Process, www.nfpa.org/regs If you have any questions or comments, please feel free to reach me at (617) 984-7434 or by e-mail at [email protected]. I look forward to our meeting to begin the revision cycle!
Technical Committee on Electrical Equipment in Chemical Atmospheres
AGENDA
NFPA 496/497/499 A2016 First Draft Meeting Sept. 30-Oct 1, 2015
Teleconference http://nfpa.adobeconnect.com/nette/
1:00 p.m. to 5:00 p.m. (Eastern Time Zone)
1. Meeting opening, introduction and attendance
2. Approval of First Draft Meeting Minutes of September 16-18, 2014 (Attachment A. September 16-
18, 2014 Meeting Minutes).
3. Chair's remarks, Bill Fiske
4. Staff Liaison update:
a. A2016 Schedule (Attachment B. A2016 Revision Cycle)
b. Committee Membership Update (Attachment C. EEC-AAA Membership)
c. Standards Process Review (Attachment D. NFPA Process – Quick Reference Guide)
5. Old Business
a. 497 Task Group Report.
b. 499 Task Group Report.
6. New Business
a. Public Comments for NFPA 496 (Attachment E. NFPA 496 - A2016 Public Comments)
b. Public Comments for NFPA 497 (Attachment F. NFPA 497 – A2016 Public Comments)
c. Public Comments for NFPA 499 (Attachment G. NFPA 499 – A2016 Public Comments)
d. Development of Second Revisions (Attachment D. NFPA Process – Quick Reference Guide)
7. Other business
8. Date/Location of Next Meeting. (First Draft Meeting for the Annual 2019 Revision Cycle)
9. Adjournment
Attachments:
A. September 16-18, 2014 Meeting Minutes
B. A2016 – Revision Cycle
C. EEC-AAA Committee Membership
D. NFPA Process – Quick Reference Guide
E. NFPA 496 - A2016 Public Comments
F. NFPA 497 – A2016 Public Comments
G. NFPA 499 - A2016 Public Comments
Attachment A:
September 16-18, 2014
Meeting Minutes
TECHNICAL COMMITTEE ON ELECTRICAL EQUIPMENT
IN CHEMICAL ATMOSPHERES
TO: TECHNICAL COMMITTEE ON ELECTRICAL EQUIPMENT IN CHEMICAL ATMOSPHERES
FROM: Eric Nette, Staff Liaison
DATE: September 23, 2014
SUBJ: REVISED--Minutes of September 16-18, 2014, First Draft Meeting (Ithaca, NY)
_________________________________________________________________________________
I. Attendance:
Members, Alternates, and Guests:
William Fiske, Committee Chair, Intertek Testing Services
Donald Ankele, Underwriters Laboratories Inc.
Ronald Brown, PPG Industries, Inc.
Jonathan Cadd, Electrical Systems and Instrumentation, Inc.
John Cawthon, State of Alaska Division of Fire & Life Safety
Paul Chantler, Sherwin Williams
Chris Cirelli, Waters Corporation
Matt Egloff, Montana Tech, University of Montana
William Lawrence, FM Global
Timothy Myers, Exponent, Inc. (via telephone)
Samuel Rodgers, Honeywell Inc.
Joseph Saverino, Air Products and Chemicals, Inc.
Rodolfo Sierra, US Coast Guard
Erdem Ural, Loss Prevention Science & Technologies (via telephone)
David Wechsler, American Chemistry Council (via telephone)
Ryan Parks, Intertek Testing Services (via telephone)
Eric Nette, NFPA, Staff Liaison
Guests:
Michael Sherman, Graco, Inc.
Robert Early, Praxair Distribution, Inc.
Guy Colonna, NFPA
Daniel Gorham, NFPA (via telephone)
EEC-AAA First Draft Meeting Minutes September XX, 2014 – page 2
II. Minutes of Meeting:
1. The Chair opened the meeting at 8:00 a.m., Tuesday September 16, 2014. 2. Attendees introduced themselves and necessary corrections were made to the
Technical Committee roster.
3. The Staff Liaison reported on the current committee roster and member
status.
Distribution Classification
Enforcers: 3, 13%
Insurance: 1, 4%
Manufacturers: 4, 17%
Applied Research/ Testing Laboratory: 2, 8%
Special Expert: 8, 33%
User: 6, 25%
Total Principle Members: 24
4. Staff introduced and reviewed NFPA’s standards development process.
5. A presentation was made by Rob Early from the NFPA Technical Committee
on Industrial and Medical Gases.
i. In response to the presentation, and at the request of Rob Early, CI-1
and CI-2 were created for NFPA 497.
6. The Committee responded to 9 Public Inputs and created 6 First Revisions to
NFPA 496. During the discussion of Public Inputs submitted by William Fiske,
The Committee was temporarily chaired by Matt Egloff.
7. The Committee responded to 18 Public Inputs, provided 3 Committee Inputs,
and created 12 First Revisions to NFPA 497.
8. The Committee responded to 13 Public Inputs, and created 7 First Revisions
to NFPA 499.
9. Next Meeting. The Committee’s next meeting will be NFPA 496, NFPA 497,
and NFPA 499 Second Draft Meeting. The Committee proposed the next
meeting to be in September, 2015. The exact date will be determined later,
but it will be in Ithaca, NY.
10. The Chair thanked everyone for their input. The Committee Meeting was
adjourned at 4:30 p.m., on Wednesday September 17, 2014.
Respectfully submitted,
Eric Nette, NFPA, Staff Liaison
Attachment B:
A2016 Revision Cycle
A2016 Revision Cycle KEY DATES Annual 2016
A2016 [EEC-AAA]
Important Dates for the Cycle:
Public Comment Closing (Paper) April 10, 2015 (DONE)
Public Comment Closing (Digital) May 15, 2015 (DONE)
Posting of Second Draft December 11, 2015
Notice of Intent to Make Motion (NITMAM) February 19, 2016
Issuance of Consent Standard May 13, 2016 (published bit later)
NFPA Annual Meeting with CAMs June 6-9, 2016
Issuance of Standard – with CAMs August 4, 2016 (published bit later)
2016 ANNUAL REVISION CYCLE *Public Input Dates may vary according to standards and schedules for Revision Cycles may change. Please check the NFPA Website for the most up‐to‐date information on Public Input Closing Dates and schedules at
www.nfpa.org/document # (i.e. www.nfpa.org/101) and click on the Next Edition tab.
Process Stage
Process Step
Dates for TC
Dates forTC with
CC Public Input Closing Date for Paper Submittal* 6/6/2014 6/6/2014
Public Input Closing Date for Online Submittal (e‐PI)* 7/7/2014 7/7/2014
Final Date for TC First Draft Meeting 12/12/2014 9/12/2014
Public Input Posting of First Draft and TC Ballot 1/30/2015 10/24/2014
Stage Final date for Receipt of TC First Draft ballot 2/20/2015 11/14/2014
(First Draft) Final date for Receipt of TC First Draft ballot ‐ recirc 2/27/2015 11/21/2014
Posting of First Draft for CC Meeting 11/28/2014
Final date for CC First Draft Meeting 1/9/2015
Posting of First Draft and CC Ballot 1/30/2015
Final date for Receipt of CC First Draft ballot 2/20/2015
Final date for Receipt of CC First Draft ballot ‐ recirc 2/27/2015
Post First Draft Report for Public Comment 3/6/2015 3/6/2015
Public Comment Closing Date for Paper Submittal* 4/10/2015 4/10/2015
Public Comment Closing Date for Online Submittal (e‐PC)* 5/15/2015 5/15/2015
Final Date to Publish Notice of Consent Standards (Standards that received no Comments)
5/29/2015 5/29/2015
Appeal Closing Date for Consent Standards (Standards that received no Comments)
6/12/2015 6/12/2015
Final date for TC Second Draft Meeting 10/30/2015 7/24/2015
Comment Posting of Second Draft and TC Ballot 12/11/2015 9/4/2015
Stage Final date for Receipt of TC Second Draft ballot 1/4/2016 9/25/2015
(Second Final date for receipt of TC Second Draft ballot ‐ recirc 1/11/2016 10/2/2015
Draft) Posting of Second Draft for CC Meeting 10/9/2015
Final date for CC Second Draft Meeting 11/20/2015
Posting of Second Draft for CC Ballot 12/11/2015
Final date for Receipt of CC Second Draft ballot 1/4/2016
Final date for Receipt of CC Second Draft ballot ‐ recirc 1/11/2016
Post Second Draft Report for NITMAM Review 1/18/2016 1/18/2016
Tech Session Notice of Intent to Make a Motion (NITMAM) Closing Date 2/19/2016 2/19/2016
Preparation Posting of Certified Amending Motions (CAMs) and Consent Standards
4/15/2016 4/15/2016
(& Issuance) Appeal Closing Date for Consent Standards 5/3/2016 5/3/2016
SC Issuance Date for Consent Standards 5/13/2016 5/13/2016
Tech Session Association Meeting for Standards with CAMs 6/13‐16/2016 6/13‐16/2016
Appeals and Appeal Closing Date for Standards with CAMs 6/29/2016 6/29/2016
Issuance SC Issuance Date for Standards with CAMs 8/4/2016 8/4/2016
Approved:__October 30, 2012 Revised___December 4, 2013_____________________
Attachment C:
EEC-AAA Committee
Membership
Address List No PhoneElectrical Equipment in Chemical Atmospheres EEC-AAA
Eric Nette08/04/2015
EEC-AAA
William T. Fiske
ChairIntertek Testing Services3933 US Route 11 SouthCortland, NY 13045-9715Alternate: Ryan Parks
RT 10/1/1994EEC-AAA
Donald W. Ankele
PrincipalUL LLC333 Pfingsten RoadNorthbrook, IL 60062-2096Alternate: John Chambers
RT 1/14/2005
EEC-AAA
Babanna Biradar
PrincipalBechtel Corporation3000 Post Oak BoulevardHouston, TX 77056Alternate: Antonino Nicotra
SE 3/2/2010EEC-AAA
Ronald M. Brown
PrincipalPPG Industries, Inc.151 Colfax StreetSpringdale, PA 15144
U 03/07/2013
EEC-AAA
Jonathan L. Cadd
PrincipalElectrical Systems and Instrumentation, Inc.1702 Ward StreetMidland, TX 79705
M 3/5/2012EEC-AAA
John H. Cawthon
PrincipalState of Alaska Division of Fire & Life Safety411 West 4th Street, Suite 2BAnchorage, AK 99501
E 8/9/2011
EEC-AAA
Paul Chantler
PrincipalSherwin Williams333 Republic101 Prospect AvenueCleveland, OH 44023
U 03/07/2013EEC-AAA
Chris Cirelli
PrincipalWaters Corporation177 Robert Treat Paine DriveTaunton, MA 02780
M 07/29/2013
EEC-AAA
Frank C. DeFelice, Jr.
PrincipalAllnex, Inc.528 South Cherry StreetWallingford, CT 06492
U 8/5/2009EEC-AAA
Matt Egloff
PrincipalMontana Tech, University of MontanaGeneral Engineering Department1300 West Park StreetButte, MT 59701
SE 1/10/2008
EEC-AAA
Felix J. Garfunkel
PrincipalParsons Corporation100 High StreetBoston, MA 02110-1713
SE 07/29/2013EEC-AAA
William G. Lawrence, Jr.
PrincipalFM Global1151 Boston-Providence TurnpikePO Box 9102Norwood, MA 02062-9102Alternate: Marlon B. Mitchell
I 1/1/1990
EEC-AAA
Robert Malanga
PrincipalFire and Risk Engineering9 Flintlock Drive, Suite 100Long Valley, NJ 07853
SE 4/17/1998EEC-AAA
Adam Morrison
PrincipalFike Corporation704 SW 10th StreetBlue Springs, MO 64015-4263
M 03/03/2014
1
Address List No PhoneElectrical Equipment in Chemical Atmospheres EEC-AAA
Eric Nette08/04/2015
EEC-AAA
Timothy J. Myers
PrincipalExponent, Inc.9 Strathmore RoadNatick, MA 01760-2418
SE 7/26/2007EEC-AAA
Samuel A. Rodgers
PrincipalHoneywell, Inc.15801 Woods Edge RoadColonial Heights, VA 23834-6059
U 4/1/1996
EEC-AAA
Joseph V. Saverino
PrincipalAir Products and Chemicals, Inc.7201 Hamilton BoulevardAllentown, PA 18195-1501
U 10/1/1994EEC-AAA
Rodolfo N. Sierra
PrincipalUS Coast GuardDesign & Engineering StandardsSystems Engineering Division (CG 5213)2100 2nd Street, SWWashington, DC 20593
E 3/4/2009
EEC-AAA
James G. Stallcup
PrincipalGrayboy, Inc.6800 Meadow CreekNorth Richland Hills, TX 76182Alternate: James W. Stallcup, Jr.
SE 1/1/1991EEC-AAA
Erdem A. Ural
PrincipalLoss Prevention Science & Technologies, Inc.2 Canton Street, Suite A2Stoughton, MA 02072
SE 8/5/2009
EEC-AAA
David B. Wechsler
Principal27706 Dalton Bluff CourtKaty, TX 77494American Chemistry Council
U 1/1/1987EEC-AAA
Jack H. Zewe
PrincipalElectrical Consultants Inc.3221 Illinois AvenueKenner, LA 70065-4530
SE 1/1/1992
EEC-AAA
Jack E. Jamison, Jr.
Voting AlternateMiller Engineering, Inc.991 River RoadMorgantown, WV 26501International Association of Electrical InspectorsVoting Alt. to IAEI Rep.
E 03/05/2012EEC-AAA
John Chambers
AlternateUL LLC333 Pfingsten RoadNorthbrook, IL 60062-2096Principal: Donald W. Ankele
RT 04/08/2015
EEC-AAA
Marlon B. Mitchell
AlternateFM Global743 Reynolds RoadWest Glocester, RI 02814Principal: William G. Lawrence, Jr.
I 10/18/2011EEC-AAA
Antonino Nicotra
AlternateBechtel Oil Gas & Chemicals3000 Post Oak BoulevardHouston, TX 77056Principal: Babanna Biradar
SE 10/29/2012
EEC-AAA
Ryan Parks
AlternateIntertek Testing Services1809 10th Street, Suite 400Plano, TX 75074-8009Principal: William T. Fiske
RT 8/5/2009EEC-AAA
James W. Stallcup, Jr.
AlternateGrayboy, Inc.6800 Meadow CreekNorth Richland Hills, TX 76182Principal: James G. Stallcup
SE 1/1/1994
2
Address List No PhoneElectrical Equipment in Chemical Atmospheres EEC-AAA
Eric Nette08/04/2015
EEC-AAA
Eric Nette
Staff LiaisonNational Fire Protection Association1 Batterymarch ParkQuincy, MA 02169-7471
04/16/2014
3
Attachment D:
NFPA Process – Quick
Reference Guide
New Process (Second Draft Stage) – Quick
Reference Guide For additional information on the New Regulations visit: www.nfpa.org/NewRegs
A Technical Committee (TC) can take these actions at the Second Draft
(ROC) meeting: 1. Resolve a Public Comment
Accept
Reject, But See Related Second Revision
Reject
Reject But hold 2. Create a Second Revision
NOTE: All actions require a Committee Statement.
Resolve Public Comment (TC needs to act upon all the Public Comments)
Accept
The TC takes the text exactly as submitted by the public comment and creates a second revision.
Sample Motion: “I move to accept PC#_.”
Approval by meeting vote (simple majority) and final approval through ballot.
Reject but See
The TC agrees with the concept of the PC in whole or part but wants to edit the text to create a second revision.
Sample Motions: i. “I move to reject PC#__, but create a second revision using it as a basis.”
ii. “I move to make a second revision using PC#__ as a basis.”
Approval by meeting vote (simple majority) and final approval through ballot.
Reject
The TC disagrees with the proposed changes in the public comment.
Sample Motion: “I move to reject PC#__.”
Approval by meeting vote (simple majority). Not subject to ballot.
Reject, but Hold.
The TC may hold any comment until the public input stage of the next revision cycle meeting any of the following criteria:
i. New concept that has not had any public review ii. The changed text would require the technical committee to restudy the
change iii. The proposed concept cannot be handled in the second draft timeframe
Sample Motion: “I move to hold PC#__.”
Approval by meeting vote (simple majority). Not subject to ballot.
Create a Second Revision (change to the document)
TC must create a Second Revision (SR) for each change they wish to make to the document. The TC can either choose to use a Public Comment for the basis of the change or not.
Using Public Comment for basis: i. See above for ACCEPT or REJECT BUT SEE.
Without using Public Comment for basis i. Sample Motion: “I make a motion to revise section __ as follows___.”
Approval by meeting vote (simple majority) and final approval through ballot.
Comparison to Previous Process:
PREVIOUS ACTIONS NEW PROCESS ACTIONS Sample Motion
Accept
1) Committee generates a Second
Revision and Substantiation (CS) for
change
2) Committee provides response (CS) to
each PC.
1) “I move to accept PC#__.”
Any variation of Accept (APA, APR,
APP) on a public comment
1) Committee rejects the comment,
but creates a Second Revision
2) Committee provides response (CS) to
each PC that is associated with the
revision
1) “I move to revise section __
using PC#_ as the basis for
change.”
2) “I move to reject PC#__, but
create a second revision using it
as a basis.”
Rejected Public Comment
1) Committee rejects the comment
2) Committee provides response (CS)
to PC
“I make a motion to reject
PC#_ with the following
committee statement__.”
Accepted Committee Comment
Committee generates a Second Revision
and Substantiation (CS) for change
“I make a motion to revise
section __ as follows___.”
Committee generates a
statement for reason for change.
Notes:
1) All meeting actions require a favorable vote of a simple majority of the members present. 2) All Second Revisions will be contained in the ballot and will require a 2/3 affirmative vote
to confirm the meeting action. 3) Only the Second Revisions will be balloted. PCs will be contained in the report but will not
be balloted.
Term Comparison between Current and Old:
CURRENT TERM OLD TERM
Input Stage ROP Stage
Public Input (PI) Proposal
First Draft Meeting ROP Meeting
Committee Input Committee Proposal that Fail
Ballot
Committee Statement
(CS) Committee Statement
First Revision (FR) Committee Proposal or Accepted
Public Proposal
First Draft Report ROP
First Draft ROP Draft
Comment Stage ROC Stage
Public Comment Public Comment
Second Draft Meeting ROC Meeting
Committee Comment Committee Comment that Fail
Ballot
Committee Action Committee Action
Second Revision Committee Comment or Accepted
Public Comment
Second Draft Report ROC
Second Draft ROC Draft
Note: The highlighted terms are the ones that will be most applicable at the Second Draft Meeting.
Attachment E:
NFPA 496 – A2016 Public
Comments
Public Comment No. 1-NFPA 496-2015 [ Section No. 1.1.1 ]
1.1.1
This standard applies to purging and pressurizing for the following:
(1) Electrical equipment located in areas classified as hazardous by Article 500, Article 505, or Article505 of 506 of NFPA 70
(2) Electrical equipment containing sources of flammable vapors or gases and located in either classifiedor unclassified areas
(3) Control rooms or buildings located in areas classified as hazardous by Article 500, Article 505, orArticle 505 506 of NFPA 70
(4) Analyzer rooms containing sources of flammable vapors or gases and located in areas classified ashazardous by Article 500, Article 505, or Article 505 of 506 of NFPA 70
Statement of Problem and Substantiation for Public Comment
Article 506 of NFPA70 references NFPA496-2013 for protection method pressurized.
Note: This is new material that was not issued in the first draft.
Related Item
Public Input No. 1-NFPA 496-2013 [Chapter 7 [Title Only]]
Submitter Information Verification
Submitter Full Name: WILLIAM MILLER
Organization: METTLER TOLEDO
Affilliation: Self
Street Address:
City:
State:
Zip:
Submittal Date: Wed Feb 18 14:18:45 EST 2015
National Fire Protection Association Report http://submittals.nfpa.org/TerraViewWeb/ContentFetcher?commentPara...
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Public Comment No. 2-NFPA 496-2015 [ Section No. 1.2 ]
1.2 Purpose.
This standard provides information on the methods for purging and pressurizing enclosures to preventignition of a flammable atmosphere. Such an atmosphere may be introduced into the enclosure by asurrounding external atmosphere or by an internal source. By these means, electrical equipment that is nototherwise acceptable for a flammable atmosphere may be utilized in accordance with Article 500, Article505, or Article 505 506 of NFPA 70.
Statement of Problem and Substantiation for Public Comment
Article 506 of NFPA70 references NFPA496-2013 for protection method pressurized.
Note: This is new material that was not issued in the first draft.
Related Item
Public Input No. 1-NFPA 496-2013 [Chapter 7 [Title Only]]
Submitter Information Verification
Submitter Full Name: WILLIAM MILLER
Organization: METTLER TOLEDO
Street Address:
City:
State:
Zip:
Submittal Date: Wed Feb 18 19:31:49 EST 2015
National Fire Protection Association Report http://submittals.nfpa.org/TerraViewWeb/ContentFetcher?commentPara...
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Attachment F:
NFPA 497 – A2016 Public
Comments
Public Comment No. 1-NFPA 497-2015 [ Chapter 2 ]
Chapter 2 Referenced Publications
2.1 General.
The documents or portions thereof listed in this chapter are referenced within this recommended practice and should beconsidered part of the recommendations of this document.
2.2 NFPA Publications.
National Fire Protection Association, 1 Batterymarch Park, Quincy, MA 02169-7471.
NFPA 30, Flammable and Combustible Liquids Code, 2015 edition.
NFPA 33, Standard for Spray Application Using Flammable or Combustible Materials, 2015 edition.
NFPA 34, Standard for Dipping, Coating, and Printing Processes Using Flammable or Combustible Liquids, 2015 edition.
NFPA 35, Standard for the Manufacture of Organic Coatings, 2016 edition.
NFPA 36, Standard for Solvent Extraction Plants, 2013 edition.
NFPA 45, Standard on Fire Protection for Laboratories Using Chemicals, 2015 edition.
NFPA 55, Compressed Gases and Cryogenic Fluids Code, 2016 edition.
NFPA 58, Liquefied Petroleum Gas Code, 2017 edition.
NFPA 59A, Standard for the Production, Storage, and Handling of Liquefied Natural Gas (LNG), 2016 edition.
NFPA 70® , National Electrical Code®, 2017 edition.
2.3 Other Publications.
2.3.1 API Publications.
American Petroleum Institute, 1220 L Street, NW, Washington, DC 20005-4070.
API RP 500, Recommended Practice for Classification of Locations for Electrical Installations at Petroleum Facilities Classifiedas Class I, Division 1 and Division 2, 3rd edition, 2008
API RP 505, Recommended Practice for Classification of Locations for Electrical Installations at Petroleum Facilities Classifiedas Class I, Zone 0, Zone 1, and Zone 2, 2002, reaffirmed 2013.
2.3.2 ASHRAE Publications.
American Society of Heating, Refrigeration and Air-Conditioning Engineers, Inc., 1791 Tullie Circle NE, Atlanta, GA30329-2305.
ASHRAE 15 ASHRAE STD 15 & 34 , Safety Standard for Refrigeration Systems, 2013. (This is a combined standard)
2.3.3 ASTM Publications.
ASTM International, 100 Barr Harbor Drive, P.O. Box C700, West Conshohocken, PA 19428-2959.
ASTM D323, Standard Method of Test for Vapor Pressure of Petroleum Products (Reid Method), 2008 ( , reapproved 2014 ) .
2.3.4 CGA Publications.
Compressed Gas Association, 14501 George Carter Way, Suite 103, Chantilly, VA 20151-2923.
CGA G2.1, Safety Requirements for the Storage and Handling of Anhydrous Ammonia, 1999 6th edition, 2014 .
2.3.5 IEC Publications.
International Electrotechnical Commission, 3, rue de Varembé, P.O. Box 131, CH-1211 Geneva 20, Switzerland.
IEC 60079-20-1, Explosive atmospheres — Part 20-1: Material characteristics for gas and vapor classification — Test methodsand data, 2012.
2.3.6 ISA Publications.
The International Society of Automation, 67 T.W. Alexander Drive, P.O. Box 12277, Research Triangle Park, NC 27709.
ISA-RP12.12.03, Standard for Portable Electronic Products Suitable for Use in Class I and II, Division 2, Class I Zone 2 andClass III, DIivision 1 and 2 Hazardous (Classified) Locations, 2011.
2.3.7 Other Publications.
Merriam-Webster’s Collegiate Dictionary, 11th edition, Merriam-Webster, Inc., Springfield, MA, 2003.
2.4 References for Extracts in Recommendations Sections.
NFPA 30, Flammable and Combustible Liquids Code, 2015 edition.
NFPA 59A, Standard for the Production, Storage, and Handling of Liquefied Natural Gas (LNG),2013 2016 edition.
NFPA 70® , National Electrical Code®,2014 2017 edition.
National Fire Protection Association Report http://submittals.nfpa.org/TerraViewWeb/ContentFetcher?commentPara...
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Statement of Problem and Substantiation for Public Comment
Updated reference to ASHRAE STD 15 & 34 which is now a combined standard. No longer two separate standards.Updated CGA G2.1 year.
Related Public Comments for This Document
Related Comment Relationship
Public Comment No. 2-NFPA 497-2015 [Section No. 4.4.2 [Excluding any Sub-Sections]]
Public Comment No. 3-NFPA 497-2015 [Chapter C]
Related Item
First Revision No. 3-NFPA 497-2014 [Chapter 2]
Submitter Information Verification
Submitter Full Name: Aaron Adamczyk
Organization: [ Not Specified ]
Street Address:
City:
State:
Zip:
Submittal Date: Fri Mar 06 20:18:48 EST 2015
National Fire Protection Association Report http://submittals.nfpa.org/TerraViewWeb/ContentFetcher?commentPara...
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Public Comment No. 2-NFPA 497-2015 [ Section No. 4.4.2 [Excluding any Sub-Sections] ]
National Fire Protection Association Report http://submittals.nfpa.org/TerraViewWeb/ContentFetcher?commentPara...
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An alphabetical listing of selected combustible materials, with their group classification and relevant physical properties, isprovided in Table 4.4.2.
Table 4.4.2 Selected Chemicals
Chemical CAS No.Class I
DivisionGroup
Type aFlashPoint(°C)
AIT(°C)
%LFL %UFL
VaporDensity(Air =
1)
Vapor
Pressure b
(mm Hg)
Class IZone
Group c
MIE(mJ)
MICRatio
MESG(mm)
Acetaldehyde 75−07−0 C d I −38 175 4.0 60.0 1.5 874.9 IIA 0.37 0.98 0.92
Acetic Acid 64−19−7 D d II 39 426 19.9 2.1 15.6 IIA 2.67 1.76
Acetic Acid- tert-ButylEster
540−88−5 D II 1.7 9.8 4.0 40.6
Acetic Anhydride 108−24−7 D II 49 316 2.7 10.3 3.5 4.9 IIA 1.23
Acetone 67−64−1 D d I –20 465 2.5 12.8 2.0 230.7 IIA 1.15 1.00 1.02
Acetone Cyanohydrin 75−86−5 D IIIA 74 688 2.2 12.0 2.9 0.3
Acetonitrile 75−05−8 D I 6 524 3.0 16.0 1.4 91.1 IIA 1.50
Acetylene 74−86−2 A d GAS 305 2.5 100 0.9 36600 IIC 0.017 0.28 0.25
Acrolein (Inhibited) 107−02−8 B(C) d I 235 2.8 31.0 1.9 274.1 IIB 0.13
Acrylic Acid 79−10−7 D II 54 438 2.4 8.0 2.5 4.3 IIB 0.86
Acrylonitrile 107−13−1 D d I 0 481 3 17 1.8 108.5 IIB 0.16 0.78 0.87
Adiponitrile 111−69−3 D IIIA 93 550 1.0 0.002
Allyl Alcohol 107−18−6 C d I 22 378 2.5 18.0 2.0 25.4 IIB 0.84
Allyl Chloride 107−05−1 D I −32 485 2.9 11.1 2.6 366 IIA 1.33 1.17
Allyl Glycidyl Ether 106−92−3 B(C) e II 57 3.9
Alpha-Methyl Styrene 98−83−9 D II 574 0.8 11.0 4.1 2.7
n-Amyl Acetate 628−63−7 D I 25 360 1.1 7.5 4.5 4.2 IIA 1.02
sec-Amyl Acetate 626−38−0 D I 23 1.1 7.5 4.5 IIA
Ammonia 7664−41−7 D d,f GAS 651 15 28 0.6 7498.0 IIA 680 6.85 3.17
Aniline 62−53−3 D IIIA 70 615 1.2 8.3 3.2 0.7 IIA
Benzene 71−43− D d I −11 498 1.2 7.8 2.8 94.8 IIA 0.20 1.00 0.99
Benzyl Chloride 98−87−3 D IIIA 585 1.1 4.4 0.5
Bromopropyne 106−96−7 D I 10 324 3.0
n-Butane 106−97−8 D d,g GAS 288 1.9 8.5 2.0 IIA 0.25 0.94 1.07
1,3-Butadiene 106−99−0 B(D) d,e GAS 420 2.0 11.5 1.9 IIB 0.13 0.76 0.79
1-Butanol 71−36−3 D d I 36 343 1.4 11.2 2.6 7.0 IIA 0.91
Butyl alcohol (s)(butanol-2)
78−92− D d I 23.8 405 1.7 9.8 2.6 IIA
Butylamine 109−73−9 D GAS −12 312 1.7 9.8 2.5 92.9 IIA 1.13
Butylene 25167−67−3 D I 385 1.6 10.0 1.9 2214.6 IIA 0.94
n-Butyraldehyde 123−72−8 C d I −12 218 1.9 12.5 2.5 112.2 IIA 0.92
n-Butyl Acetate 123−86−4 D d I 22 421 1.7 7.6 4.0 11.5 IIA 1.08 1.04
sec-Butyl Acetate 105−46−4 D II −8 1.7 9.8 4.0 22.2
tert-Butyl Acetate 540−88−5 D II 1.7 9.8 4.0 40.6
n-Butyl Acrylate(Inhibited)
141−32−2 D II 49 293 1.7 9.9 4.4 5.5 IIB 0.88
n-Butyl Glycidyl Ether 2426−08−6 B(C) e II
n-Butyl Formal 110−62−3 C IIIA 34.3
Butyl Mercaptan 109−79−5 C I 2 3.1 46.4
Butyl-2-Propenoate 141−32−2 D II 49 1.7 9.9 4.4 5.5
para tert-Butyl Toluene 98−51−1 D IIIA
n-Butyric Acid 107−92−6 D d IIIA 72 443 2.0 10.0 3.0 0.8
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4 of 18 5/18/2015 11:12 AM
Chemical CAS No.Class I
DivisionGroup
Type aFlashPoint(°C)
AIT(°C)
%LFL %UFL
VaporDensity(Air =
1)
Vapor
Pressure b
(mm Hg)
Class IZone
Group c
MIE(mJ)
MICRatio
MESG(mm)
Carbon Disulfide 75−15−0 d,h I −30 90 1.3 50.0 2.6 358.8 IIC 0.009 0.39 0.20
Carbon Monoxide 630−08−0 C d GAS 609 12.5 74 0.97 IIB 0.54
Chloroacetaldehyde 107−20−0 C IIIA 88 63.1
Chlorobenzene 108−90−7 D I 29 593 1.3 9.6 3.9 11.9
1-Chloro-1-Nitropropane
2425−66−3 C IIIA
Chloroprene 126−99−8 D GAS −20 4.0 20.0 3.0
Cresol 1319−77−3 D IIIA 81 559 1.1 3.7
Crotonaldehyde 4170−30−3 C d I 13 232 2.1 15.5 2.4 33.1 IIB 0.81
Cumene 98−82−8 D I 36 424 0.9 6.5 4.1 4.6 IIA 1.05
Cyclohexane 110−82−7 D I −17 245 1.3 8.0 2.9 98.8 IIA 0.22 1.0 0.94
Cyclohexanol 108−93−0 D IIIA 68 300 3.5 0.7 IIA
Cyclohexanone 108−94−1 D II 44 420 1.1 9.4 3.4 4.3 IIA 0.98
Cyclohexene 110−83−8 D I −6 244 1.2 2.8 89.4 IIA 0.97
Cyclopropane 75−19−4 D d I 503 2.4 10.4 1.5 5430 IIA 0.17 0.84 0.91
p-Cymene 99−87-6 D II 47 436 0.7 5.6 4.6 1.5 IIA
Decene 872−05−9 D II 235 4.8 1.7
n-Decaldehyde 112−31−2 C IIIA 0.09
n-Decanol 112−30−1 D IIIA 82 288 5.3 0.008
Decyl Alcohol 112−30−1 D IIIA 82 288 5.3 0.008
Diacetone Alcohol 123−42−2 D IIIA 64 603 1.8 6.9 4.0 1.4
Di-Isobutylene 25167−70−8 D d I 2 391 0.8 4.8 3.8 0.96
Di-Isobutyl Ketone 108−83−8 D II 60 396 0.8 7.1 4.9 1.7
o-Dichlorobenzene 955−50−1 D IIIA 66 647 2.2 9.2 5.1 IIA
1,4-Dichloro-2,3Epoxybutane
3583−47−9 D d I 1.9 8.5 2.0 IIA 0.25 0.98 1.07
1,1-Dichloroethane 1300−21−6 D I 438 6.2 16.0 3.4 227 IIA 1.82
1,2-Dichloroethylene 156−59−2 D I 97 460 5.6 12.8 3.4 204 IIA 3.91
1,1-Dichloro-1-Nitroethane
594−72−9 C IIIA 76 5.0
1,3-Dichloropropene 10061−02−6 D I 35 5.3 14.5 3.8
Dicyclopentadiene 77−73−6 C I 32 503 2.8 IIA 0.91
Diethylamine 109−87−9 C d I −28 312 1.8 10.1 2.5 IIA 1.15
Diethylaminoethanol 100−37−8 C IIIA 60 320 4.0 1.6 IIA
Diethyl Benzene 25340−17−4 D II 57 395 4.6
Diethyl Ether (EthylEther)
60−29−7 C d I −45 160 1.9 36 2.6 538 IIB 0.19 0.88 0.83
Diethylene GlycolMonobutyl Ether
112−34−5 C IIIA 78 228 0.9 24.6 5.6 0.02
Diethylene GlycolMonomethyl Ether
111−77−3 C IIIA 93 241 0.2
n-n-Dimethyl Aniline 121−69−7 C IIIA 63 371 1.0 4.2 0.7
Dimethyl Formamide 68−12−2 D II 58 455 2.2 15.2 2.5 4.1 IIA 1.08
Dimethyl Sulfate 77−78-1 D IIIA 83 188 4.4 0.7
Dimethylamine 124−40−3 C GAS 400 2.8 14.4 1.6 IIA
2,2-Dimethylbutane 75−83−2 D g I −48 405 319.3
2,3-Dimethylbutane 78−29−8 D g I 396
3,3-Dimethylheptane 1071−26-7 D g I 325 10.8
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5 of 18 5/18/2015 11:12 AM
Chemical CAS No.Class I
DivisionGroup
Type aFlashPoint(°C)
AIT(°C)
%LFL %UFL
VaporDensity(Air =
1)
Vapor
Pressure b
(mm Hg)
Class IZone
Group c
MIE(mJ)
MICRatio
MESG(mm)
2,3-Dimethylhexane 31394−54−4 D g I 438
2,3-Dimethylpentane 107−83−5 D g I 335 211.7
Di-N-Propylamine 142−84−7 C I 17 299 27.1 IIA 0.95
1,4-Dioxane 123−91−1 C d I 12 180 2.0 22.0 3.0 38.2 IIB 0.19 0.70
Dipentene 138−86−3 D II 45 237 0.7 6.1 4.7 IIA 1.18
Dipropylene GlycolMethyl Ether
34590−94−8 C IIIA 85 1.1 3.0 5.1 0.5
Diisopropylamine 108−18−9 C GAS −6 316 1.1 7.1 3.5 IIA 1.02
Dodecene 6842−15−5 D IIIA 100 255
Epichlorohydrin 3132−64−7 C d I 33 411 3.8 21.0 3.2 13.0
Ethane 74−84−0 D d GAS −29 472 3.0 12.5 1.0 IIA 0.24 0.82 0.91
Ethanol 64−17−5 D d I 13 363 3.3 19.0 1.6 59.5 IIA 0.88 0.89
Ethylamine 75−04−7 D d I −18 385 3.5 14.0 1.6 1048 2.4
Ethylene 74−85−1 C d GAS 490 2.7 36.0 1.0 IIB 0.070 0.53 0.65
Ethylenediamine 107−15−3 D d I 33 385 2.5 12.0 2.1 12.5
Ethylenimine 151−56−4 C d I −11 320 3.3 54.8 1.5 211 0.48
Ethylene Chlorohydrin 107−07−3 D IIIA 59 425 4.9 15.9 2.8 7.2
Ethylene Dichloride 107−06−2 D d I 13 413 6.2 16.0 3.4 79.7
Ethylene GlycolMonoethyl EtherAcetate
111−15−9 C II 47 379 1.7 4.7 2.3 IIA 0.53 0.97
Ethylene GlycolMonobutyl EtherAcetate
112−07−2 C IIIA 340 0.9 8.5 0.9
Ethylene GlycolMonobutyl Ether
111−76−2 C IIIA 238 1.1 12.7 4.1 1.0
Ethylene GlycolMonoethyl Ether
110−80−5 C II 235 1.7 15.6 3.0 5.4 0.84
Ethylene GlycolMonomethyl Ether
109−86−4 D II 285 1.8 14.0 2.6 9.2 0.85
Ethylene Oxide 75−21−8 B(C) d,e I −20 429 3 100 1.5 1314 IIB 0.065 0.47 0.59
2-Ethylhexaldehyde 123−05−7 C II 52 191 0.8 7.2 4.4 1.9
2-Ethylhexanol 104−76−7 D IIIA 81 0.9 9.7 4.5 0.2
2-Ethylhexyl Acrylate 103−09−3 D IIIA 88 252 0.3
Ethyl Acetate 141−78−6 D d I −4 427 2.0 11.5 3.0 93.2 IIA 0.46 0.99
Ethyl Acrylate(Inhibited)
140−88−5 D d I 9 372 1.4 14.0 3.5 37.5 IIA 0.86
Ethyl Alcohol 64−17−5 D d I 13 363 3.3 19.0 1.6 59.5 IIA 0.88 0.89
Ethyl Sec-Amyl Ketone 541−85−5 D II 59
Ethyl Benzene 100−41−4 D I 15 432 0.8 6.7 3.7 9.6
Ethyl Butanol 97−95−0 D II 57 1.2 7.7 3.5 1.5
Ethyl Butyl Ketone 106−35−4 D II 46 4.0 3.6
Ethyl Chloride 75−00−3 D GAS −50 519 3.8 15.4 2.2
Ethyl Formate 109−94−4 D GAS −20 455 2.8 16.0 2.6 IIA 0.94
Ethyl Mercaptan 75−08−1 C d I −18 300 2.8 18.0 2.1 527.4 IIB 0.90 0.90
n-Ethyl Morpholine 100−74−3 C I 32 4.0
2-Ethyl-3-PropylAcrolein
645−62−5 C IIIA 68 4.4
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6 of 18 5/18/2015 11:12 AM
Chemical CAS No.Class I
DivisionGroup
Type aFlashPoint(°C)
AIT(°C)
%LFL %UFL
VaporDensity(Air =
1)
Vapor
Pressure b
(mm Hg)
Class IZone
Group c
MIE(mJ)
MICRatio
MESG(mm)
Ethyl Silicate 78−10−4 D II 7.2
Formaldehyde (Gas) 50−00−0 B GAS 430 7 73 1.0 IIB 0.57
Formic Acid 64−18−6 D II 50 434 18.0 57.0 1.6 42.7 IIA 1.86
Fuel Oil 1 8008−20−6 DII or
IIIA k 38−72 k 210 0.7 5.0
Fuel Oil 2II or
IIIA k 52−96 k 257
Fuel Oil 6IIIA or
IIIB k 66–132 k
Furfural 98−01−1 C IIIA 60 316 2.1 19.3 3.3 2.3 0.94
Furfuryl Alcohol 98−00−0 C IIIA 75 490 1.8 16.3 3.4 0.6
Gasoline 8006−61−9 D d I −46 280 1.4 7.6 3.0
n-Heptane 142−82−5 D d I −4 204 1.0 6.7 3.5 45.5 IIA 0.24 0.88 0.91
n-Heptene 81624−04−6 D g I −1 204 3.4 0.97
n-Hexane 110−54−3 D d,g I −23 225 1.1 7.5 3.0 152 IIA 0.24 0.88 0.93
Hexanol 111−27−3 D IIIA 63 3.5 0.8 IIA 0.98
2-Hexanone 591−78−6 D I 35 424 1.2 8.0 3.5 10.6
Hexene 592−41−6 D I −26 245 1.2 6.9 186
sec-Hexyl Acetate 108−84−9 D II 45 5.0
Hydrazine 302−01−2 C II 38 23 98.0 1.1 14.4
Hydrogen 1333−74−0 B d GAS 500 4 75 0.1 IIC 0.019 0.25 0.28
Hydrogen Cyanide 74−90−8 C d GAS −18 538 5.6 40.0 0.9 IIB 0.80
Hydrogen Selenide 7783−07−5 C I 7793
Hydrogen Sulfide 7783−06−4 C d GAS 260 4.0 44.0 1.2 IIB 0.068 0.90
Isoamyl Acetate 123−92−2 D I 25 360 1.0 7.5 4.5 6.1
Isoamyl Alcohol 123−51−3 D II 43 350 1.2 9.0 3.0 3.2 IIA 1.02
Isobutane 75−28−5 D g GAS 460 1.8 8.4 2.0 IIA 0.95
Isobutyl Acetate 110−19−0 D d I 18 421 2.4 10.5 4.0 17.8
Isobutyl Acrylate 106−63−8 D I 427 4.4 7.1
Isobutyl Alcohol 78−83−1 D d I −40 416 1.2 10.9 2.5 10.5 IIA 0.92 0.98
Isobutyraldehyde 78−84−2 C GAS −40 196 1.6 10.6 2.5 IIA 0.92
Isodecaldehyde 112−31−2 C IIIA 5.4 0.09
Isohexane 107−83−5 D g 264 211.7 IIA 1.00
Isopentane 78−78−4 D g 420 688.6
Isooctyl Aldehyde 123−05−7 C II 197 1.9
Isophorone 78−59−1 D 84 460 0.8 3.8 4.8 0.4
Isoprene 78−79−5 D d I −54 220 1.5 8.9 2.4 550.6
Isopropyl Acetate 108−21−4 D I 460 1.8 8.0 3.5 60.4
Isopropyl Ether 108−20−3 D d I −28 443 1.4 7.9 3.5 148.7 IIA 1.14 0.94
Isopropyl GlycidylEther
4016−14−2 C I
Isopropylamine 75−31−0 D GAS −26 402 2.3 10.4 2.0 2.0
Kerosene 8008−20−6 D II 72 210 0.7 5.0 IIA
Liquefied PetroleumGas
68476−8−7 D I 405
Mesityl Oxide 141−97−9 D d I 31 344 1.4 7.2 3.4 47.6
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7 of 18 5/18/2015 11:12 AM
Chemical CAS No.Class I
DivisionGroup
Type aFlashPoint(°C)
AIT(°C)
%LFL %UFL
VaporDensity(Air =
1)
Vapor
Pressure b
(mm Hg)
Class IZone
Group c
MIE(mJ)
MICRatio
MESG(mm)
Methane 74−82−8 D d GAS 600 5 15 0.6 IIA 0.28 1.00 1.12
Methanol 67−56−1 D d I 12 385 6.0 36.0 1.1 126.3 IIA 0.14 0.82 0.92
Methyl Acetate 79−20−9 D GAS −10 454 3.1 16.0 2.6 IIA 1.08 0.99
Methyl Acrylate 96−33−3 D GAS −3 468 2.8 25.0 3.0 IIB 0.98 0.85
Methyl Alcohol 67−56−1 D d I 385 6.0 36 1.1 126.3 IIA 0.91
Methyl Amyl Alcohol 108−11−2 D II 41 1.0 5.5 3.5 5.3 IIA 1.01
Methyl Chloride 74−87−3 D GAS −46 632 8.1 17.4 1.7 IIA 1.00
Methyl Ether 115−10−6 C d GAS −41 350 3.4 27.0 1.6 IIB 0.85 0.84
Methyl Ethyl Ketone 78−93−3 D d I −6 404 1.4 11.4 2.5 92.4 IIB 0.53 0.92 0.84
Methyl Formal 534−15−6 C d I 1 238 3.1
Methyl Formate 107−31−3 D GAS −19 449 4.5 23.0 2.1 IIA 0.94
2-Methylhexane 31394−54−4 D g I 280
Methyl Isobutyl Ketone 108−10−1 D d I 13 440 1.2 8.0 3.5 11
Methyl Isocyanate 624−83−9 D GAS −15 534 5.3 26.0 2.0 IIA 1.21
Methyl Mercaptan 74−93−1 C GAS −18 3.9 21.8 1.7
Methyl Methacrylate 80−62−6 D I 10 422 1.7 8.2 3.6 37.2 IIA 0.95
Methyl N-Amyl Ketone 110−43−0 D II 49 393 1.1 7.9 3.9 3.8
Methyl Tertiary ButylEther
1634−04−4 D I −80 435 1.6 8.4 0.2 250.1
2-Methyloctane 3221−61−2 220 6.3
2-Methylpropane 75−28−5 D g I 460 2639
Methyl-1-Propanol 78−83−1 D d I −40 416 1.2 10.9 2.5 10.1 IIA 0.98
Methyl-2-Propanol 75−65−0 D d I 10 360 2.4 8.0 2.6 42.2
2-Methyl-5-EthylPyridine
104−90−5 D 74 1.1 6.6 4.2
Methylacetylene 74−99−7 C d I 1.7 1.4 4306 0.11
Methylacetylene-Propadiene
27846−30−6 C I IIB 0.74
Methylal 109−87−5 C I −18 237 1.6 17.6 2.6 398
Methylamine 74−89−5 D GAS 430 4.9 20.7 1.0 IIA 1.10
2-Methylbutane 78−78−4 D g −56 420 1.4 8.3 2.6 688.6
Methylcyclohexane 208−87−2 D I −4 250 1.2 6.7 3.4 0.27
Methylcyclohexanol 25630−42−3 D 68 296 3.9
2-Methycyclohexanone 583−60−8 D II 3.9
2-Methylheptane D g 420
3-Methylhexane 589−34−4 D g 280 61.5
3-Methylpentane 94−14−0 D g 278
2-Methylpropane 75−28−5 D g I 460 2639
2-Methyl-1-Propanol 78−83−1 D d I −40 223 1.2 10.9 2.5 10.5
2-Methyl-2-Propanol 75−65−0 D d I 478 2.4 8.0 2.6 42.2
2-Methyloctane 2216−32−2 D g 220
3-Methyloctane 2216−33−3 D g 220 6.3
4-Methyloctane 2216−34−4 D g 225 6.8
Monoethanolamine 141−43−5 D 85 410 2.1 0.4 IIA
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8 of 18 5/18/2015 11:12 AM
Chemical CAS No.Class I
DivisionGroup
Type aFlashPoint(°C)
AIT(°C)
%LFL %UFL
VaporDensity(Air =
1)
Vapor
Pressure b
(mm Hg)
Class IZone
Group c
MIE(mJ)
MICRatio
MESG(mm)
Monoisopropanolamine 78−96−6 D 77 374 2.6 1.1
Monomethyl Aniline 100−61−8 C 482 0.5
Monomethyl Hydrazine 60−34−4 C I 23 194 2.5 92.0 1.6
Morpholine 110−91−8 C d II 35 310 1.4 11.2 3.0 10.1 IIA 0.95
Naphtha (Coal Tar) 8030−30−6 D II 42 277 IIA
Naphtha (Petroleum) 8030−30−6 D d,i I 42 288 1.1 5.9 2.5 IIA
Neopentane 463−82−1 D g −65 450 1.4 8.3 2.6 1286
Nitrobenzene 98−95−3 D 88 482 1.8 4.3 0.3 IIA 0.94
Nitroethane 79−24−3 C I 28 414 3.4 2.6 20.7 IIB 0.87
Nitromethane 75−52−5 C I 35 418 7.3 2.1 36.1 IIA 0.92 1.17
1-Nitropropane 108−03−2 C I 34 421 2.2 3.1 10.1 IIB 0.84
2-Nitropropane 79−46−9 C d I 28 428 2.6 11.0 3.1 17.1
n-Nonane 111−84−2 D g I 31 205 0.8 2.9 4.4 4.4 IIA
Nonene 27214−95−8 D I 0.8 4.4
Nonyl Alcohol 143−08−8 D 0.8 6.1 5.0 0.02 IIA
n-Octane 111−65−9 D d,g I 13 206 1.0 6.5 3.9 14.0 IIA 0.94
Octene 25377−83−7 D I 8 230 0.9 3.9
n-Octyl Alcohol 111−87−5 D 4.5 0.08 IIA 1.05
n-Pentane 109−66−0 D d,g I −40 243 1.5 7.8 2.5 513 IIA 0.28 0.97 0.93
1-Pentanol 71−41−0 D d I 33 300 1.2 10.0 3.0 2.5 IIA 1.30
2-Pentanone 107−87−9 D I 7 452 1.5 8.2 3.0 35.6 IIA 0.99
1-Pentene 109−67−1 D I −18 275 1.5 8.7 2.4 639.7
2-Pentene 109−68−2 D I −18 2.4
2-Pentyl Acetate 626−38−0 D I 23 1.1 7.5 4.5
Phenylhydrazine 100−63−0 D 89 3.7 0.03
Process Gas > 30%H 2
B j GAS 520 4.0 75.0 0.1 0.019 0.45
Propane 74−98−6 D d GAS 450 2.1 9.5 1.6 IIA 0.25 0.82 0.97
1-Propanol 71−23−8 D d I 15 413 2.2 13.7 2.1 20.7 IIA 0.89
2-Propanol 67−63−0 D d I 12 399 2.0 12.7 2.1 45.4 IIA 0.65 1.00
Propiolactone 57−57−8 D 2.9 2.5 2.2
Propionaldehyde 123−38−6 C I −9 207 2.6 17.0 2.0 318.5 IIB 0.86
Propionic Acid 79−09−4 D II 54 466 2.9 12.1 2.5 3.7 IIA 1.10
Propionic Anhydride 123−62−6 D 74 285 1.3 9.5 4.5 1.4
n-Propyl Acetate 109−60−4 D I 14 450 1.7 8.0 3.5 33.4 IIA 1.05
n-Propyl Ether 111−43−3 C d I 21 215 1.3 7.0 3.5 62.3
Propyl Nitrate 627−13−4 B d I 20 175 2.0 100.0
Propylene 115−07−1 D d GAS 460 2.4 10.3 1.5 IIA 0.28 0.91
Propylene Dichloride 78−87−5 D I 16 557 3.4 14.5 3.9 51.7 IIA 1.32
Propylene Oxide 75−56−9 B(C) d,e I −37 449 2.3 36.0 2.0 534.4 IIB 0.13 0.70
Pyridine 110−86−1 D d I 20 482 1.8 12.4 2.7 20.8 IIA
Styrene 100−42−5 D d I 31 490 0.9 6.8 3.6 6.1 IIA 1.21
Tetrahydrofuran 109−99−9 C d I −14 321 2.0 11.8 2.5 161.6 IIB 0.54 0.87
Tetrahydronaphthalene 119−64−2 D IIIA 385 0.8 5.0 4.6 0.4
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Chemical CAS No.Class I
DivisionGroup
Type aFlashPoint(°C)
AIT(°C)
%LFL %UFL
VaporDensity(Air =
1)
Vapor
Pressure b
(mm Hg)
Class IZone
Group c
MIE(mJ)
MICRatio
MESG(mm)
Tetramethyl Lead 75−74−1 C II 38 9.2
Toluene 108−88−3 D d I 4 480 1.1 7.1 3.1 28.53 IIA 0.24
n-Tridecene 2437−56−1 D IIIA 0.6 6.4 593.4
Triethylamine 121−44−8 C d I −9 249 1.2 8.0 3.5 68.5 IIA 0.75 1.05
Triethylbenzene 25340−18−5 D 83 56.0 5.6
2,2,3-Trimethylbutane D g 442
2,2,4-Trimethylbutane D g 407
2,2,3-Trimethylpentane D g 396
2,2,4-Trimethylpentane D g 415 IIA 1.04
2,3,3-Trimethylpentane D g 425
Tripropylamine 102−69−2 D II 41 4.9 1.5 IIA 1.13
Turpentine 8006−64−2 D I 35 253 0.8 4.8
n-Undecene 28761−27−5 D IIIA 0.7 5.5
UnsymmetricalDimethyl Hydrazine
57−14−7 C d I −15 249 2.0 95.0 1.9 IIB 0.85
Valeraldehyde 110−62−3 C I 280 222 3.0 34.3
Vinyl Acetate 108−05−4 D d I −6 402 2.6 13.4 3.0 113.4 IIA 0.70 0.94
Vinyl Chloride 75−01−4 D d GAS −78 472 3.6 33.0 2.2 IIA 0.96
Vinyl Toluene 25013−15−4 D 52 494 0.8 11.0 4.1
Vinylidene Chloride 75−35−4 D I 570 6.5 15.5 3.4 599.4 IIA 3.91
Xylene 1330−20-7 D d I 25 464 0.9 7.0 3.7 IIA 0.2 1.09
Xylidine 121−69−7 C IIIA 63 371 1.0 4.2 0.7
aType is used to designate if the material is a gas, flammable liquid, or combustible liquid. (See 4.2.6 and 4.2.7.)
bVapor pressure reflected in units of mm Hg at 77°F (25°C) unless stated otherwise.
cClass I, Zone Groups are based on 1996 IEC TR3 60079-20-1, Explosive atmospheres — Part 20-1:Material characteristicsfor gas and vapor classification — Test methods and data, which contains additional data on MESG and group classifications.
dMaterial has been classified by test.
eWhere all conduit runs into explosionproof equipment are provided with explosionproof seals installed within 18 in. (450 mm)of the enclosure, equipment for the group classification shown in parentheses is permitted.
fFor classification of areas involving ammonia, see ASHRAE 15, Safety Standard for Refrigeration Systems, and CGA G2.1,Safety Requirements for the Storage and Handling of Anhydrous Ammonia.
gCommercial grades of aliphatic hydrocarbon solvents are mixtures of several isomers of the same chemical formula (ormolecular weight). The autoignition temperatures (AIT) of the individual isomers are significantly different. The electricalequipment should be suitable for the AIT of the solvent mixture. (See A.4.4.2.)
hCertain chemicals have characteristics that require safeguards beyond those required for any of the above groups. Carbondisulfide is one of these chemicals because of its low autoignition temperature and the small joint clearance necessary to arrestits flame propagation.
iPetroleum naphtha is a saturated hydrocarbon mixture whose boiling range is 68°F to 275°F (20°C to 135°C). It is also knownas benzine, ligroin, petroleum ether, and naphtha.
jFuel and process gas mixtures found by test not to present hazards similar to those of hydrogen may be grouped based on thetest results.
k Liquid type and flash point vary due to regional blending differences.
Statement of Problem and Substantiation for Public Comment
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Updated Table 4.4.2 note c by updating reference to IEC 60079-20-1.
Related Public Comments for This Document
Related Comment Relationship
Public Comment No. 1-NFPA 497-2015 [Chapter 2] Referenced current standard names and years
Public Comment No. 3-NFPA 497-2015 [Chapter C]
Related Item
First Revision No. 4-NFPA 497-2014 [Section No. 4.4.2]
Submitter Information Verification
Submitter Full Name: Aaron Adamczyk
Organization: [ Not Specified ]
Street Address:
City:
State:
Zip:
Submittal Date: Fri Mar 06 20:39:09 EST 2015
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Public Comment No. 7-NFPA 497-2015 [ New Section after 5.10 ]
(new) Figure Compressed Gas Cylinders
Insert new figure 9.5.x and 10.5.x for Heavier than Air
Insert new figure 9.5.x1 and 10.5.x2 for Lighter than Air
See attached graphic.
Additional Proposed Changes
File Name Description Approved
Compressed_gas_cylinders.docx Compressed gas figures for Division and Zone, Heavier than air and lighter than air
Statement of Problem and Substantiation for Public Comment
As discussed there was a need to address gas cylinder storage classification
Related Item
First Revision No. 11-NFPA 497-2014 [Section No. 5.9 [Excluding any Sub-Sections]]
Submitter Information Verification
Submitter Full Name: DAVID WECHSLER
Organization: [ Not Specified ]
Street Address:
City:
State:
Zip:
Submittal Date: Thu May 14 14:45:45 EDT 2015
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Public Comment No. 5-NFPA 497-2015 [ Section No. 5.10.8 ]
5.10.8 Storage of Liquid or Gaseous Hydrogen. Replace drawings with attached figures
[See Figure 5.10.8(a) and Figure 5.10.8(b).]
Figure 5.10.8(a) Liquid Hydrogen Storage Located Outdoors or Indoors in an Adequately Ventilated Building. Thisdiagram applies to liquid hydrogen only.
Figure 5.10.8(b) Gaseous Hydrogen Storage Located Outdoors or Indoors in an Adequately Ventilated Building. Thisdiagram applies to gaseous hydrogen only.
Additional Proposed Changes
File Name Description Approved
CYLINDERS_Division.pdf Gas storage in cylinders - divisions
FILL_CONNECTION_LIQUID_Division.pdf Liquid hydrogen storage fill connection - divisions
RECEIVERS_Division.pdf Gas hydrogen storage in receivers - divisions
TANK_AND_VAPORIZER_LIQUID_Division.pdf Liquid hydrogen storage - tank and vaporizer - divisions
VENT_STACK_GAS_Division.pdf Gas hydrogen vent stack - divisions
VENT_STACK_LIQUID_Division.pdf Liquid hydrogen vent stack - divisions
section_5.10.8_figures_-_divisions.docx Complete set of figures and figure numbers for divisions
Statement of Problem and Substantiation for Public Comment
Updates drawings to match material in 2016 edition of NFPA 55
Related Item
Committee Input No. 1-NFPA 497-2014 [Section No. 5.9.8]
Submitter Information Verification
Submitter Full Name: ROB EARLY
Organization: PRAXAIR
Affilliation: NFPA Industrial and Medical Gases Committee
Street Address:
City:
State:
Zip:
Submittal Date: Mon May 11 16:21:00 EDT 2015
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1
Figure 5.10.8(a) – liquid hydrogen storage – tank and vaporizer (part of system containing liquid hydrogen)
2
Figure 5.10.8(b) – liquid hydrogen tank fill connection
3
Figure 5.10.8(c) – liquid hydrogen vent stack
4
Figure 5.10.8(d) – gas hydrogen storage – receivers
5
Figure 5.10.8(e) – gas hydrogen storage – cylinders
6
Figure 5.10.8(f) – gas hydrogen vent stack
Public Comment No. 8-NFPA 497-2015 [ Section No. 5.10.8 ]
5.10.8 Storage of Liquid or Gaseous Hydrogen. Update figures with attachments - alternate updates
[See Figure 5.10.8(a) and Figure 5.10.8(b).]
Figure 5.10.8(a) Liquid Hydrogen Storage Located Outdoors or Indoors in an Adequately Ventilated Building. Thisdiagram applies to liquid hydrogen only.
Figure 5.10.8(b) Gaseous Hydrogen Storage Located Outdoors or Indoors in an Adequately Ventilated Building. Thisdiagram applies to gaseous hydrogen only.
Additional Proposed Changes
File Name Description Approved
section_5.10.8_figures_-_divisions_-_alternate.pdf figures for divisions - alternate
Statement of Problem and Substantiation for Public Comment
Updating to match NFPA 55 classified area requirements
Related Item
Committee Input No. 1-NFPA 497-2014 [Section No. 5.9.8]
Submitter Information Verification
Submitter Full Name: ROB EARLY
Organization: PRAXAIR
Affilliation: NFPA Industrial and Medical Gases Committee
Street Address:
City:
State:
Zip:
Submittal Date: Thu May 14 15:07:02 EDT 2015
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Public Comment No. 6-NFPA 497-2015 [ Section No. 5.11.8 ]
5.11.8 Storage of Liquid or Gaseous Hydrogen. Replace drawings with attached figures.
[See Figure 5.11.8(a) and Figure 5.11.8(b).]
Figure 5.11.8(a) Liquid Hydrogen Storage Located Outdoors or Indoors in an Adequately Ventilated Building. Thisdiagram applies to liquid hydrogen only.
Figure 5.11.8(b) Gaseous Hydrogen Storage Located Outdoors, or Indoors in an Adequately Ventilated Building. Thisdiagram applies to gaseous hydrogen only.
Additional Proposed Changes
File Name Description Approved
CYLINDERS_Zone.pdf Gas hydrogen storage in cylinders - zones
FILL_CONNECTION_LIQUID_Zone.pdf Liquid hydrogen fill connection - zone
RECEIVERS_Zone.pdf Gas hydrogen storage in receivers - zones
TANK_AND_VAPORIZER_LIQUID_Zone.pdf Liquid hydrogen storage - tank and vaporizer - zones
VENT_STACK_GAS_Zone.pdf Gas hydrogen vent stack - zones
VENT_STACK_LIQUID_Zone.pdf Liquid hydrogen vent stack - zones
section_5.11.8_figures_-_zones.docx complete set of figures and figure numbers for zones
Statement of Problem and Substantiation for Public Comment
Harmonizes figures with updates in NFPA 55, 2016 edition
Related Item
Committee Input No. 2-NFPA 497-2014 [Section No. 5.10.8]
Submitter Information Verification
Submitter Full Name: ROB EARLY
Organization: PRAXAIR
Affilliation: NFPA Industrial and Medical Gases committee
Street Address:
City:
State:
Zip:
Submittal Date: Mon May 11 16:30:44 EDT 2015
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1
Figure 5.11.8(a) – liquid hydrogen storage – tank and vaporizer (part of system containing liquid hydrogen)
2
Figure 5.11.8(b) – liquid hydrogen tank fill connection
3
Figure 5.11.8(c) – liquid hydrogen vent stack
4
Figure 5.11.8(d) – gas hydrogen storage – receivers
5
Figure 5.11.8(e) – gas hydrogen storage – cylinders
6
Figure 5.11.8(f) – gas hydrogen vent stack
Public Comment No. 9-NFPA 497-2015 [ Section No. 5.11.8 ]
5.11.8 Storage of Liquid or Gaseous Hydrogen. Update with attached drawings - alternate
[See Figure 5.11.8(a) and Figure 5.11.8(b).]
Figure 5.11.8(a) Liquid Hydrogen Storage Located Outdoors or Indoors in an Adequately Ventilated Building. Thisdiagram applies to liquid hydrogen only.
Figure 5.11.8(b) Gaseous Hydrogen Storage Located Outdoors, or Indoors in an Adequately Ventilated Building. Thisdiagram applies to gaseous hydrogen only.
Additional Proposed Changes
File Name Description Approved
section_5.11.8_figures_-_zones_-_alternate.pdf updated figures - alternate
Statement of Problem and Substantiation for Public Comment
updates figures to match NFPA 55
Related Item
Committee Input No. 2-NFPA 497-2014 [Section No. 5.10.8]
Submitter Information Verification
Submitter Full Name: ROB EARLY
Organization: PRAXAIR
Affilliation: NFPA Industrial and Medical Gases Committee
Street Address:
City:
State:
Zip:
Submittal Date: Thu May 14 15:09:17 EDT 2015
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Public Comment No. 3-NFPA 497-2015 [ Chapter C ]
Annex C Informational References
C.1 Reference Publications.
The documents or portions thereof listed in this annex are referenced within the informational sections of this recommendedpractice and are not part of the recommendations of this document unless also listed in Chapter 2 for other reasons.
C.1.1 NFPA Publications.
National Fire Protection Association, 1 Batterymarch Park, Quincy, MA 02169-7471.
NFPA 70 ®, National Electrical Code ®, 2014.
NFPA Fire Protection Guide to Hazardous Materials, 2010.
C.1.2 Other Publications.
C.1.2.1 ASTM Publications.
ASTM International, 100 Barr Harbor Drive, P.O. Box C700, West Conshohocken, PA 19428–2959.
ASTM E659, Standard Test Method for Autoignition Temperature of Liquid Chemicals, 2014.
C.1.2.2 IEC Publications.
International Electrotechnical Commission, 3, rue de Varembé, P.O. Box 131, CH-1211 Geneva 20, Switzerland.
IEC 60079-1-1, Electrical apparatus for explosive gas atmospheres, Part 1-1: Flameproof enclosures “d”— Method of test forascertainment of maximum experimental safe gap , 2002 (Superseded by IEC 60079-20-1) .
IEC 60079-11, Explosive atmospheres — Part 11: Equipment protection by intrinsic safety “I,” 2012.
IEC 60079-20, - 1, Explosive atmospheres —Part 20-1: Material characteristics of gas and vapor classification — Testmethods and data, .2012.
C.1.2.3 NAS Publications.
National Materials Advisory Board of the National Academy of Sciences, 500 Fifth Street, NW, Washington, DC 20055.
NMAB 353-1, Matrix of Combustion-Relevant Properties and Classification of Gases, Vapors and Selected Solids, 1979.
C.1.2.4 UL Publications.
Underwriters Laboratories Inc., 333 Pfingsten Road, Northbrook, IL 60062-2096.
Technical Report No. 58 (TR 58), An Investigation of Flammable Gases or Vapors with Respect to Explosion-Proof ElectricalEquipment, 1993. (Withdrawn)
C.1.2.5 Other Publications.
Brandes, E. and Redeker, T. “Maximum Experimental Safe Gap of Binary and Ternary Mixtures.” Journal de Physique IVFrance, Vol. 12, No. 7, 2002.
Lunn, G. A., “Maximum Experimental Safe Gap: The Effects of Oxygen Enrichment and the Influence of Reaction Kinetics,”Journal of Hazardous Materials, 261–270, 1984.
Phillips, H. “Differences Between Determinations of Maximum Experimental Safe Gaps in Europe and U.S.A.” Journal ofHazardous Materials, 1981.
Thomas, G., “Pipeline Explosions I: An Evaluation of MESG as a Relative Measure of Potential Explosion Severity and theGenesis of a Mimic Gas Concept for Explosion Hazard Testing,” 5th Int. Seminar on Fire and Explosion Hazards, Edinburgh,Scotland, 2007.
C.2 Informational References.
The following documents or portions thereof are listed here as informational resources only. They are not a part of therecommendations of this document.
C.2.1 ASHRAE Publications.
American Society of Heating, Refrigeration and Air-Conditioning Engineers, Inc., 1791 Tullie Circle, NE, Atlanta, GA30329-2305.
ASHRAE STD 15 & 34, Designation and Safety Classification of Refrigerants Saftey Standard for Refrigeration Systems ,2013, Errata, 2015 . (This is now a combined standard.)
C.2.2 ASTM Publications.
ASTM International, 100 Barr Harbor Drive, P.O. Box C700, West Conshohocken, PA 19428-2959.
ASTM D56, Standard Method of Test for Flash Point by the Tag Closed Tester, 2005, reapproved 2010 .
ASTM D93, Standard Test Method for Flash Point by Pensky-Martens Closed Cup Tester, 2013.
ASTM D3278, Standard Method of Tests for Flash Point of Liquids by Small Scale Closed-Cup Apparatus, 1996, reapproved2011 .
ASTM E681, Standard Test Method for Concentration Limits of Flammability of Chemicals (Vapors and Gases), 2009.
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C.2.3 Bureau of Mines Publications.
U.S. Government Printing Office, Washington, DC 20402.
RI 7009, Minimum Ignition Energy and Quenching Distance in Gaseous Mixture.
C.2.4 Other Publications.
Energy Institute (Institute of Petroleum), Model Code of Safe Practice for the Petroleum Industry, Part 15: Area ClassificationCode for Installations Handling Flammable Fluids, 2008.
Hilado, C. J., and S. W. Clark. “Autoignition Temperatures of Organic Chemicals.” Chemical Engineering, September 4, 1972.
Rodgers, S. A., “Fuel Ratio Method for Estimating the MESG of Nitrogen-Diluted and Oxygen-Enriched Fuels, Including theBrandes-Redeker Method to Estimate the MESG of Mixed Fuels,” AIChE 6th Global Congress on Process Safety, 44th AnnualLoss Prevention Symposium, San Antonio, TX March 22–24, 2010.
C.3 References for Extracts in Informational Sections.
(Reserved)
Statement of Problem and Substantiation for Public Comment
IEC 60079-1-1 superseded by IEC 60079-20-1.UL TR 58 has been withdrawn.
Related Public Comments for This Document
Related Comment Relationship
Public Comment No. 1-NFPA 497-2015 [Chapter 2]Referenced current standard names, andyears.
Public Comment No. 2-NFPA 497-2015 [Section No. 4.4.2 [Excluding anySub-Sections]]
Referenced current standard name in notec.
Related Item
First Revision No. 12-NFPA 497-2014 [Chapter C]
Submitter Information Verification
Submitter Full Name: Aaron Adamczyk
Organization: [ Not Specified ]
Street Address:
City:
State:
Zip:
Submittal Date: Fri Mar 06 20:47:19 EST 2015
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Attachment G:
NFPA 499 – A2016 Public
Comments
Public Comment No. 1-NFPA 499-2015 [ Section No. 1.2 ]
1.2 Purpose.
1.2.1
The purpose of this recommended practice is to provide the user with a basic understanding of theparameters that determine the degree and the extent of the hazardous (classified) location. Thisrecommended practice also provides the user with examples of the applications of these parameters.
1.2.2
This recommended practice is intended as a guide and should be applied with sound engineeringjudgment. Where all factors are properly evaluated, a consistent area classification scheme can bedeveloped.
1.2.3
This recommended practice is based on the criteria established by Articles 500 and 502 of NFPA 70.
1.2.4
The application of this recommended practice does not address all potential hazards associated with solidparticulate materials, including, but not limited to, the possible need for explosion venting or explosionsuppression addressed in other NFPA standards.
1.2.5
This recommended practice does not address the criteria for classifying locations in accordance with Article506 of NFPA 70 .
Statement of Problem and Substantiation for Public Comment
Note: for Clarification - This comment only applies to the deletion of 1.2.5 and not all 1.2.
It had been suggested by Public Input to include dust zones within NFPA 499. During this session, the Committee received apparently incorrect information that having more than one ANSI standard dealing with Hazardous Area Classification for Zones for combustible dusts would violate ANSI regulations. Precedent already exists for ANSI supported standards dealing with HAC zone methodology. These include NFPA 497, API 505, ISA 60079-10, just to name a few. Additionally since the US National Electrical Code provides a method in which Division equipment may be used in Zones and vice versa (in some cases), there should be no reasonable rational for not permitting Zone methodology to be applied with combustilble dusts as outlined with the repeated public input now Public comments made in support of adding Zones for combustible dusts in 499.
Related Public Comments for This Document
Related Comment Relationship
Public Comment No. 2-NFPA 499-2015 [New Section after 4.3]
Public Comment No. 3-NFPA 499-2015 [New Section after 5.1.4]
Public Comment No. 4-NFPA 499-2015 [New Section after 5.2.1]
Public Comment No. 5-NFPA 499-2015 [Section No. 5.2.2]
Public Comment No. 6-NFPA 499-2015 [Section No. 6.10]
Public Comment No. 9-NFPA 499-2015 [Section No. 6.7]
Public Comment No. 10-NFPA 499-2015 [Section No. A.6.3.2]
Public Comment No. 11-NFPA 499-2015 [Section No. A.6.7]
Public Comment No. 12-NFPA 499-2015 [Section No. 6.3]
Public Comment No. 13-NFPA 499-2015 [Section No. 6.4]
Public Comment No. 14-NFPA 499-2015 [Section No. 6.6.3]
Public Comment No. 15-NFPA 499-2015 [Chapter 6]
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Related Item
Public Input No. 28-NFPA 499-2014 [New Section after 4.3]
Submitter Information Verification
Submitter Full Name: David Wechsler
Organization: [ Not Specified ]
Street Address:
City:
State:
Zip:
Submittal Date: Thu Mar 05 10:20:07 EST 2015
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Public Comment No. 2-NFPA 499-2015 [ New Section after 4.3 ]
TITLE OF NEW CONTENT
Type your content here ...
Renumber existing 4.3 to 4.4 Additional Potential Combustible Dust Hazards and add the following
new section 4.3 as shown:
4.3 Classification of Combustible Dusts
4.3.1 Combustible Dust Groups. Combustible dusts are addressed in the National Electrical Code,
in Articles 500, 502, and 506.
4.3.2 In Class II- Divisions, hazardous (classified) location the combustible dust are divided into Groups E,F,
and G.
4.3.2.1 Group E. Atmospheres containing combustible metal dusts, including aluminum, magnesium, and
their commercial alloys, or other combustible dusts whose particle size, abrasiveness, and conductivity
present similar hazards in the use of electrical equipment.
4.3.2.2 (retain appendix material 3.3.4.2*) Group F. Atmospheres containing combustible
carbonaceous dusts that have more than 8 percent total entrapped volatiles (see ASTM D 3175,
Standard Test Method for Volatile Matter in the Analysis Sample of Coal and Coke, for coal and
coke dusts) or that have been sensitized by other materials so that they present an explosion
hazard.
4.3.2.3 (retain appendix material 3.3.4.3*) Group G. Atmospheres containing combustible dusts notincluded
in Group E or Group F, including flour, grain, wood, plastic, and chemicals.
4.3.3 In Class II- Zones, hazardous (classified) location the combustible dust are divided into Zone Groups
IIIC and IIIB.
4.3.3.1 Zone Group IIIC. Atmospheres containing combustible metal dusts, including aluminum,magnesium,
and their commercial alloys, or other combustible dusts whose particle size, abrasiveness, and conductivity
present similar hazards in the use of electrical equipment.
4.3.3.2 Zone Group IIIB. Atmospheres containing 1) combustible carbonaceous dusts that have more than8
percent total entrapped volatiles (see ASTM D 3175, Standard Test Method for Volatile Matter in the
Analysis Sample of Coal and Coke, for coal and coke dusts) or that have been sensitized by othermaterials
so that they present an explosion hazard or 2) combustible dusts not included in Zone Group IIIC including
flour, grain, wood, plastic, and chemicals.
Informational Note No. 1: Ignitible fibers and flyings addressed in NEC Article 506 are not considered
combustible dusts under the scope of this recommended practice.
4.3.4 5.2.2* A listing of selected combustible dusts with their group classification and relevant physical
properties is provided in Table 4.x.x (former Table 5.2.2). The chemicals are listed alphabetically.
Revise this table to include new column showing Zone Groups and editing this information in this new
column by adding IIIB across from each G and F entry, and IIIC across each E entry
4.3.5 5.2.3 Table 4.x.x (former Table 5.2.3) provides a cross-reference of selected chemicals sorted by their
Chemical Abstract Service (CAS) numbers.
4.3.6 5.2.4 References that deal with the testing of various characteristics of combustible materials arelisted
in B.2.1, B.2.2, and B.2.4.
Statement of Problem and Substantiation for Public Comment
Added material is needed to support the inclusion of the Zone methodolgy for combustible dusts as shown in the
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earlier Public Input 28.
Related Public Comments for This Document
Related Comment Relationship
Public Comment No. 1-NFPA 499-2015[Section No. 1.2]
Supports the addition of Zone methodology which was notpermitted by clause 1.2.5
Public Comment No. 3-NFPA 499-2015 [NewSection after 5.1.4]
Public Comment No. 4-NFPA 499-2015 [NewSection after 5.2.1]
Public Comment No. 5-NFPA 499-2015[Section No. 5.2.2]
Public Comment No. 6-NFPA 499-2015[Section No. 6.10]
Public Comment No. 9-NFPA 499-2015[Section No. 6.7]
Related Item
Public Input No. 28-NFPA 499-2014 [New Section after 4.3]
Submitter Information Verification
Submitter Full Name: David Wechsler
Organization: [ Not Specified ]
Street Address:
City:
State:
Zip:
Submittal Date: Thu Mar 05 10:40:57 EST 2015
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Public Comment No. 3-NFPA 499-2015 [ New Section after 5.1.4 ]
TITLE OF NEW CONTENT
Type your content here ...
Add new section 5.1.4 as shown below:
5.1.4 Class II –Zone hazardous (classified) location is further subdivided into either Class II, Zone 20, Zone
21 or Zone 22, in which combustible dust are or may be present in the air or in layers, in quantities
sufficient to produce explosive or ignitible mixtures.
5.1.4.1 Zone 20. A Zone 20 location is a location in which (a) Ignitible concentrations of combustible dust
are present continuously.
(b) Ignitible concentrations of combustible dust are present for long periods of time.
5.1.4.2 Zone 21. A Zone 21 location is a location (a) In which ignitible concentrations of combustible dustare
likely to exist occasionally under normal operating conditions; or (b) In which ignitible concentrations of
combustible dust may exist frequently because of repair or maintenance operations or because of leakage;
or (c) In which equipment is operated or processes are carried on, of such a nature that equipment
breakdown or faulty operations could result in the release of ignitable concentrations of combustible dust
and also cause simultaneous failure of electrical equipment in a mode to cause the electrical equipment to
become a source of ignition; or (d) That is adjacent to a Zone 20 location from which ignitible
concentrations of dust could be communicated, unless communication is prevented by adequate
positive pressure ventilation from a source of clean air and effective safeguards against ventilation.
5.1.4.3 Zone 22. A Zone 22 location is a location (a) In which ignitible concentrations of combustible dustare
not likely to occur in normal operation and, if they do occur, will only persist for a short period; or (b) Inwhich
combustible dust are handled, processed, or used but in which the dust are normally confined within closed
containers of closed systems from which they can escape only as a result of the abnormal operation of the
equipment with which the dust are handled, processed, or used; or (c) That is adjacent to a Zone 21
location, from which ignitible concentrations of dust could be communicated, unless such communication is
prevented by adequate positive pressure ventilation from a source of clean air and effective safeguards
against ventilation failure are provided.
Statement of Problem and Substantiation for Public Comment
With the inclusion of Combustible Dust Zones, the relavent document texts required revision based upon NECArticle 506 addressing Zone 20, 21, and 22, combustible Dust locations based upon the NEC
Related Public Comments for This Document
Related Comment Relationship
Public Comment No. 1-NFPA 499-2015 [Section No. 1.2]Action supports inclusion of Zonemethodology
Public Comment No. 2-NFPA 499-2015 [New Section after4.3]
Action supports inclusion of Zonemethodology
Public Comment No. 4-NFPA 499-2015 [New Section after5.2.1]
Public Comment No. 5-NFPA 499-2015 [Section No. 5.2.2]
Public Comment No. 6-NFPA 499-2015 [Section No. 6.10]
Related Item
Public Input No. 30-NFPA 499-2014 [New Section after 5.1.4]
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Submitter Information Verification
Submitter Full Name: David Wechsler
Organization: [ Not Specified ]
Street Address:
City:
State:
Zip:
Submittal Date: Thu Mar 05 10:54:40 EST 2015
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Public Comment No. 7-NFPA 499-2015 [ Section No. 5.1.9 ]
5.1.9*
Where Group E dusts are present in hazardous quantities, there are only Division 1 locations.
Statement of Problem and Substantiation for Public Comment
This material is more correctly addressed in 5.1.3.1 (3) which follows the NEC.
Related Public Comments for This Document
Related Comment Relationship
Public Comment No. 8-NFPA 499-2015 [Section No. A.5.1.9]
Related Item
First Revision No. 5-NFPA 499-2014 [Section No. 5.1.9]
Submitter Information Verification
Submitter Full Name: David Wechsler
Organization: [ Not Specified ]
Street Address:
City:
State:
Zip:
Submittal Date: Tue Mar 10 08:58:29 EDT 2015
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Public Comment No. 4-NFPA 499-2015 [ New Section after 5.2.1 ]
TITLE OF NEW CONTENT
Type your content here ...
Add new section 5.2.2 and renumber accordingly:
New 5.2.2 Combustible Zone Dust Groups. Combustible Zone dusts are addressed
in the National Electrical Code , in Article 506 and are divided into Groups IIIC, and IIIB.
5.2.2.1 Group IIIC. Atmospheres containing combustible metal dusts, including aluminum, magnesium, and
their commercial alloys, or other combustible dusts whose particle size, abrasiveness, and conductivity
present similar hazards in the use of electrical equipment.
5.2.2.2 Group IIIB. Atmospheres containing combustible carbonaceous dusts that have more than 8
percent total entrapped volatiles (see ASTM D 3175, Standard Test Method for Volatile Matter in the
Analysis Sample of Coal and Coke , for coal and coke dusts) or that have been sensitized by other
materials so that they present an explosion hazard, or atmospheres containing combustible dusts not
included in Group IIIC, including flour, grain, wood, plastic, and chemicals.
Statement of Problem and Substantiation for Public Comment
Texts support the inclusion of these material groups for Combustible Zone dust groups
Related Public Comments for This Document
Related Comment Relationship
Public Comment No. 1-NFPA 499-2015 [Section No. 1.2] Deals with Zone methodology
Public Comment No. 2-NFPA 499-2015 [New Section after 4.3] Deals with Zone methodology
Public Comment No. 3-NFPA 499-2015 [New Section after 5.1.4] Deals with Zone methodology
Public Comment No. 5-NFPA 499-2015 [Section No. 5.2.2]
Public Comment No. 6-NFPA 499-2015 [Section No. 6.10]
Public Comment No. 9-NFPA 499-2015 [Section No. 6.7]
Related Item
Public Input No. 24-NFPA 499-2014 [New Section after 5.2.1]
Submitter Information Verification
Submitter Full Name: David Wechsler
Organization: [ Not Specified ]
Street Address:
City:
State:
Zip:
Submittal Date: Thu Mar 05 10:58:33 EST 2015
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Public Comment No. 5-NFPA 499-2015 [ Section No. 5.2.2 ]
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5.2.2*
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A listing of selected combustible dusts with their group classification and relevant physical properties isprovided in Table 5.2.2. The chemicals are listed alphabetically.
Table 5.2.2 Selected Combustible Dusts
Chemical Name CAS No.
NEC
Group CodeLayer or Cloud Ignition
Temperature (°C)
Acetal, linear G NL 440
Acetoacet-p-phenetidide 122-82-7 G NL 560
Acetoacetanilide 102-01-2 G M 440
Acetylamino-t-nitrothiazole G 450
Acrylamide polymer G 240
Acrylonitrile polymer G 460
Acrylonitrile-vinyl chloride-vinylidenechloridecopolymer (70-20-10)
G 210
Acrylonitrile-vinyl pyridine copolymer G 240
Adipic acid 124-04-9 G M 550
Alfalfa meal G 200
Alkyl ketone dimer sizing compound G 160
Allyl alcohol derivative (CR-39) G NL 500
Almond shell G 200
Aluminum, A422 flake 7429-90-5 E 320
Aluminum, atomized collector fines E CL 550
Aluminum—cobalt alloy (60-40) E 570
Aluminum—copper alloy (50-50) E 830
Aluminum—lithium alloy (15% Li) E 400
Aluminum—magnesium alloy (dowmetal) E CL 430
Aluminum—nickel alloy (58-42) E 540
Aluminum—silicon alloy (12% Si) E NL 670
Amino-5-nitrothiazole 121-66-4 G 460
Anthranilic acid 118-92-3 G M 580
Apricot pit G 230
Aryl-nitrosomethylamide G NL 490
Asphalt 8052-42-4 F 510
Aspirin [acetol (2)] 50-78-2 G M 660
Azelaic acid 109-31-9 G M 610
Azo-bis-butyronitrile 78-67-1 G 350
Benzethonium chloride G CL 380
Benzoic acid 65-85-0 G M 620
Benzotriazole 95-14-7 G M 440
Beta-naphthalene-axo-
dimethylanilineG 175
Bis(2-hydroxy-
5-chlorophenyl) methane97-23-4 G NL 570
Bisphenol-A 80-05-7 G M 570
Boron, commercial amorphous (85% B) 7440-42-8 E 400
Calcium silicide E 540
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Chemical Name CAS No.
NEC
Group CodeLayer or Cloud Ignition
Temperature (°C)
Carbon black (more than 8% total entrappedvolatiles)
F
Carboxymethyl cellulose 9000-11-7 G 290
Carboxypolymethylene G NL 520
Cashew oil, phenolic, hard G 180
Cellulose G 260
Cellulose acetate G 340
Cellulose acetate butyrate G NL 370
Cellulose triacetate G NL 430
Charcoal (activated) 64365-11-3 F 180
Charcoal (more than 8% total entrappedvolatiles)
F
Cherry pit G 220
Chlorinated phenol G NL 570
Chlorinated polyether alcohol G 460
Chloroacetoacetanilide 101-92-8 G M 640
Chromium (97%) electrolytic, milled 7440-47-3 E 400
Cinnamon G 230
Citrus peel G 270
Coal, Kentucky bituminous F 180
Coal, Pittsburgh experimental F 170
Coal, Wyoming F 180
Cocoa bean shell G 370
Cocoa, natural, 19% fat G 240
Coconut shell G 220
Coke (more than 8% total entrapped volatiles) F
Cork G 210
Corn G 250
Corn dextrine G 370
Corncob grit G 240
Cornstarch, commercial G 330
Cornstarch, modified G 200
Cottonseed meal G 200
Coumarone-indene, hard G NL 520
Crag No. 974 533-74-4 G CL 310
Cube root, South America 83-79-4 G 230
Di-alphacumyl peroxide, 40-60 on CA 80-43-3 G 180
Diallyl phthalate 131-17-9 G M 480
Dicyclopentadiene dioxide G NL 420
Dieldrin (20%) 60-57-1 G NL 550
Dihydroacetic acid G NL 430
Dimethyl isophthalate 1459-93-4 G M 580
Dimethyl terephthalate 120-61-6 G M 570
Dinitro-o-toluamide 148-01-6 G NL 500
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Chemical Name CAS No.
NEC
Group CodeLayer or Cloud Ignition
Temperature (°C)
Dinitrobenzoic acid G NL 460
Diphenyl 92-52-4 G M 630
Ditertiary-butyl-paracresol 128-37-0 G NL 420
Dithane m-45 8018-01-7 G 180
Epoxy G NL 540
Epoxy-bisphenol A G NL 510
Ethyl cellulose G CL 320
Ethyl hydroxyethyl cellulose G NL 390
Ethylene oxide polymer G NL 350
Ethylene-maleic anhydride copolymer G NL 540
Ferbam™ 14484-64-1 G 150
Ferromanganese, medium carbon 12604-53-4 E 290
Ferrosilicon (88% Si, 9% Fe) 8049-17-0 E 800
Ferrotitanium (19% Ti, 74.1% Fe, 0.06% C) E CL 380
Flax shive G 230
Fumaric acid 110-17-8 G M 520
Garlic, dehydrated G NL 360
Gilsonite 12002-43-6 F 500
Green base harmon dye G 175
Guar seed G NL 500
Gulasonic acid, diacetone G NL 420
Gum, arabic G 260
Gum, karaya G 240
Gum, manila G CL 360
Gum, tragacanth 9000-65-1 G 260
Hemp hurd G 220
Hexamethylene tetramine 100-97-0 G S 410
Hydroxyethyl cellulose G NL 410
Iron, 98% H2 reduced E 290
Iron, 99% carbonyl 13463-40-6 E 310
Isotoic anhydride G NL 700
L-sorbose G M 370
Lignin, hydrolized, wood-type, fine G NL 450
Lignite, California F 180
Lycopodium G 190
Malt barley G 250
Manganese 7439-96-5 E 240
Magnesium, grade B, milled E 430
Manganese vancide G 120
Mannitol 69-65-8 G M 460
Methacrylic acid polymer G 290
Methionine (l-methionine) 63-68-3 G 360
Methyl cellulose G 340
Methyl methacrylate polymer 9011-14-7 G NL 440
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Chemical Name CAS No.
NEC
Group CodeLayer or Cloud Ignition
Temperature (°C)
Methyl methacrylate-ethyl acrylate G NL 440
Methyl methacrylate-styrene-
butadieneG NL 480
Milk, skimmed G 200
N,N-dimethylthio-
formamideG 230
Nitropyridone 100703-82-0 G M 430
Nitrosamine G NL 270
Nylon polymer 63428-84-2 G 430
Para-oxy-benzaldehyde 123-08-0 G CL 380
Paraphenylene diamine 106-50-3 G M 620
Paratertiary butyl benzoic acid 98-73-7 G M 560
Pea flour G 260
Peach pit shell G 210
Peanut hull G 210
Peat, sphagnum 94114-14-4 G 240
Pecan nut shell 8002-03-7 G 210
Pectin 5328-37-0 G 200
Pentaerythritol 115-77-5 G M 400
Petrin acrylate monomer 7659-34-9 G NL 220
Petroleum coke (more than 8% total entrappedvolatiles)
F
Petroleum resin 64742-16-1 G 500
Phenol formaldehyde 9003-35-4 G NL 580
Phenol formaldehyde, polyalkylene-p 9003-35-4 G 290
Phenol furfural 26338-61-4 G 310
Phenylbetanaphthylamine 135-88-6 G NL 680
Phthalic anydride 85-44-9 G M 650
Phthalimide 85-41-6 G M 630
Pitch, coal tar 65996-93-2 F NL 710
Pitch, petroleum 68187-58-6 F NL 630
Polycarbonate G NL 710
Polyethylene, high pressure process 9002-88-4 G 380
Polyethylene, low pressure process 9002-88-4 G NL 420
Polyethylene terephthalate 25038-59-9 G NL 500
Polyethylene wax 68441-04-8 G NL 400
Polypropylene (no antioxidant) 9003-07-0 G NL 420
Polystyrene latex 9003-53-6 G 500
Polystyrene molding compound 9003-53-6 G NL 560
Polyurethane foam, fire retardant 9009-54-5 G 390
Polyurethane foam, no fire retardant 9009-54-5 G 440
Polyvinyl acetate 9003-20-7 G NL 550
Polyvinyl acetate/alcohol 9002-89-5 G 440
Polyvinyl butyral 63148-65-2 G 390
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Chemical Name CAS No.
NEC
Group CodeLayer or Cloud Ignition
Temperature (°C)
Polyvinyl chloride-dioctyl phthalate G NL 320
Potato starch, dextrinated 9005-25-8 G NL 440
Pyrethrum 8003-34-7 G 210
Rayon (viscose) flock 61788-77-0 G 250
Red dye intermediate G 175
Rice G 220
Rice bran G NL 490
Rice hull G 220
Rosin, DK 8050-09-7 G NL 390
Rubber, crude, hard 9006-04-6 G NL 350
Rubber, synthetic, hard (33% S) 64706-29-2 G NL 320
Safflower meal G 210
Salicylanilide 87-17-2 G M 610
Sevin 63-25-2 G 140
Shale, oil 68308-34-9 F
Shellac 9000-59-3 G NL 400
Sodium resinate 61790-51-0 G 220
Sorbic acid (copper sorbate or potash) 110-44-1 G 460
Soy flour 68513-95-1 G 190
Soy protein 9010-10-0 G 260
Stearic acid, aluminum salt 637-12-7 G 300
Stearic acid, zinc salt 557-05-1 G M 510
Styrene modified polyester-glass fiber 100-42-5 G 360
Styrene-acrylonitrile (70-30) 9003-54-7 G NL 500
Styrene-butadiene latex (>75% styrene) 903-55-8 G NL 440
Styrene-maleic anhydride copolymer 9011-13-6 G CL 470
Sucrose 57-50-1 G CL 350
Sugar, powdered 57-50-1 G CL 370
Sulfur 7704-34-9 G 220
Tantalum 7440-25-7 E 300
Terephthalic acid 100-21-0 G NL 680
Thorium (contains 1.2% O) 7440-29-1 E CL 270
Tin, 96%, atomized (2% Pb) 7440-31-5 E 430
Titanium, 99% Ti 7440-32-6 E CL 330
Titanium hydride (95% Ti, 3.8% H) 7704-98-5 E CL 480
Trithiobisdimethylthio-
formamideG 230
Tung, kernels, oil-free 8001-20-5 G 240
Urea formaldehyde molding compound 9011-05-6 G NL 460
Urea formaldehyde-phenol formaldehyde 25104-55-6 G 240
Vanadium, 86.4% 7440-62-2 E 490
Vinyl chloride-acrylonitrile copolymer 9003-00-3 G 470
Vinyl toluene-acrylonitrile butadiene 76404-69-8 G NL 530
Violet 200 dye G 175
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Chemical Name CAS No.
NEC
Group CodeLayer or Cloud Ignition
Temperature (°C)
Vitamin B1, mononitrate 59-43-8 G NL 360
Vitamin C 50-81-7 G 280
Walnut shell, black G 220
Wheat G 220
Wheat flour 130498-22-5 G 360
Wheat gluten, gum 100684-25-1 G NL 520
Wheat starch G NL 380
Wheat straw G 220
Wood flour G 260
Woodbark, ground G 250
Yeast, torula 68602-94-8 G 260
Zirconium hydride 7704-99-6 E 270
Zirconium (contains 0.3% O) 7440-67-7 E CL 330
Notes:
(1) Normally, the minimum ignition temperature of a layer of a specific dust is lower than the minimumignition temperature of a cloud of that dust. Since this is not universally true, the lower of the two minimumignition temperatures is listed. If no symbol appears in the “Code” column, then the layer ignitiontemperature is shown. “CL” means the cloud ignition temperature is shown. “NL” means that no layerignition temperature is available, and the cloud ignition temperature is shown. “M” signifies that the dustlayer melts before it ignites; the cloud ignition temperature is shown. “S” signifies that the dust layersublimes before it ignites; the cloud ignition temperature is shown.
(2) Certain metal dusts might have characteristics that require safeguards beyond those required foratmospheres containing the dusts of aluminum, magnesium, and their commercial alloys. For example,zirconium and thorium dusts can ignite spontaneously in air, especially at elevated temperatures.
(3) Due to the impurities found in coal, its ignition temperatures vary regionally, and ignition temperaturesare not available for all regions in which coal is mined.
Additional Proposed Changes
File Name Description Approved
499_table_4.5.2_revised.rtfReplace existing table with this revised table reflecting Combustible Zone Dust Groups.
Statement of Problem and Substantiation for Public Comment
Table needs to be revised to reflect the Combustible Zone dusts, added with Section 5.2.2
Related Public Comments for This Document
Related Comment Relationship
Public Comment No. 1-NFPA 499-2015 [Section No. 1.2] Supports Zone methodology
Public Comment No. 2-NFPA 499-2015 [New Section after 4.3] Supports Zone methodology
Public Comment No. 3-NFPA 499-2015 [New Section after 5.1.4] Supports Zone methodology
Public Comment No. 4-NFPA 499-2015 [New Section after 5.2.1] Supports Zone methodology
Public Comment No. 6-NFPA 499-2015 [Section No. 6.10]
Public Comment No. 9-NFPA 499-2015 [Section No. 6.7]
Public Comment No. 12-NFPA 499-2015 [Section No. 6.3]
Related Item
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Public Input No. 25-NFPA 499-2014 [Section No. 5.2.2]
Submitter Information Verification
Submitter Full Name: David Wechsler
Organization: [ Not Specified ]
Street Address:
City:
State:
Zip:
Submittal Date: Thu Mar 05 11:15:47 EST 2015
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Table 4.5.2 Selected Combustible Materials
Chemical Name CAS No. Division Grp/
Zone Group
Code Layer or Cloud
Ignition Temp.
(°C)
Acetal, Linear G/IIIB NL 440
Acetoacet-p-phenetidide 122-82-7 G//IIIB NL 560
Acetoacetanilide 102-01-2 G//IIIB M 440
Acetylamino-t-nitrothiazole G//IIIB 450
Acrylamide Polymer G/IIIB 240
Acrylonitrile Polymer G//IIIB 460
Acrylonitrile-Vinyl Chloride-Vinylidenechloride copolymer
(70-20-10)
G//IIIB 210
Acrylonitrile-Vinyl Pyridine Copolymer G//IIIB 240
Adipic Acid 124-04-9 G//IIIB M 550
Alfalfa Meal G//IIIB 200
Alkyl Ketone Dimer Sizing Compound G//IIIB 160
Allyl Alcohol Derivative (CR-39) G//IIIB NL 500
Almond Shell G//IIIB 200
Aluminum, A422 Flake 7429-90-5 E/IIIC 320
Aluminum, Atomized Collector Fines E/IIIC CL 550
Aluminum—cobalt alloy (60-40) E/IIIC 570
Aluminum—copper alloy (50-50) E/IIIC 830
Aluminum—lithium alloy (15% Li) E/IIIC 400
Aluminum—magnesium alloy (Dowmetal) E/IIIC CL 430
Aluminum—nickel alloy (58-42) E/IIIC 540
Aluminum—silicon alloy (12% Si) E/IIIC NL 670
Amino-5-nitrothiazole 121-66-4 G/IIIB 460
Anthranilic Acid 118-92-3 G/IIIB M 580
Apricot Pit G/IIIB 230
Aryl-nitrosomethylamide G/IIIB NL 490
Asphalt 8052-42-4 F/IIIB 510
Aspirin [acetol (2)] 50-78-2 G/IIIB M 660
Azelaic Acid 109-31-9 G/IIIB M 610
Azo-bis-butyronitrile 78-67-1 G/IIIB 350
Benzethonium Chloride G/IIIB CL 380
Benzoic Acid 65-85-0 G/IIIB M 440
Benzotriazole 95-14-7 G/IIIB M 440
Beta-naphthalene-axo-dimethylaniline G/IIIB 175
Bis(2-hydroxy-5-chlorophenyl) Methane 97-23-4 G/IIIB NL 570
Bisphenol-A 80-05-7 G/IIIB M 570
Boron, Commercial Amorphous (85% B) 7440-42-8 E/IIIC 400
Calcium Silicide E/IIIC 540
Carbon Black (More Than 8% Total Entrapped Volatiles) F/IIIB
Carboxymethyl Cellulose 9000-11-7 G/IIIB 290
Carboxypolymethylene G/IIIB NL 520
Cashew Oil, Phenolic, Hard G/IIIB 180
Cellulose G/IIIB 260
Cellulose Acetate G/IIIB 340
Cellulose Acetate Butyrate G/IIIB NL 370
Cellulose Triacetate G/IIIB NL 430
Charcoal (Activated) 64365-11-3 F/IIIB 180
Charcoal (More Than 8% Total Entrapped Volatiles) F/IIIB
Cherry Pit G/IIIB 220
Chlorinated Phenol G/IIIB NL 570
Chlorinated Polyether Alcohol G/IIIB 460
Chloroacetoacetanilide 101-92-8 G/IIIB M 640
Chromium (97%) Electrolytic, Milled 7440-47-3 E/IIIC 400
Cinnamon G/IIIB 230
Citrus Peel G/IIIB 270
Coal, Kentucky Bituminous F/IIIB 180
Coal, Pittsburgh Experimental F/IIIB 170
Coal, Wyoming F/IIIB 180
Cocoa Bean Shell G/IIIB 370
Cocoa, Natural, 19% Fat G/IIIB 240
Coconut Shell G/IIIB 220
Coke (More Than 8% Total Entrapped Volatiles) F/IIIB
Cork G/IIIB 210
Corn G/IIIB 250
Corn Dextrine G/IIIB 370
Corncob Grit G/IIIB 240
Cornstarch, Commercial G/IIIB 330
Cornstarch, Modified G/IIIB 200
Cottonseed Meal G/IIIB 200
Coumarone-Indene, Hard G/IIIB NL 520
Crag No. 974 533-74-4 G/IIIB CL 310
Cube Root, South America 83-79-4 G/IIIB 230
Di-alphacumyl Peroxide, 40-60 on CA 80-43-3 G/IIIB 180
Diallyl Phthalate 131-17-9 G/IIIB M 480
Dicyclopentadiene Dioxide G/IIIB NL 420
Dieldrin (20%) 60-57-1 G/IIIB NL 550
Dihydroacetic Acid G/IIIB NL 430
Dimethyl Isophthalate 1459-93-4 G/IIIB M 580
Dimethyl Terephthalate 120-61-6 G/IIIB M 570
Dinitro-o-toluamide 148-01-6 G/IIIB NL 500
Dinitrobenzoic Acid G/IIIB NL 460
Diphenyl 92-52-4 G/IIIB M 630
Ditertiary-butyl-paracresol 128-37-0 G/IIIB NL 420
Dithane m-45 8018-01-7 G/IIIB 180
Epoxy G/IIIB NL 540
Epoxy-bisphenol A G/IIIB NL 510
Ethyl Cellulose G/IIIB CL 320
Ethyl Hydroxyethyl Cellulose G/IIIB NL 390
Ethylene Oxide Polymer G/IIIB NL 350
Ethylene-maleic Anhydride Copolymer G/IIIB NL 540
Ferbam™ 14484-64-1 G/IIIB 150
Ferromanganese, Medium Carbon 12604-53-4 E/IIIC 290
Ferrosilicon (88% Si, 9% Fe) 8049-17-0 E/IIIC 800
Ferrotitanium (19% Ti, 74.1% Fe, 0.06% C) E/IIIC CL 380
Flax Shive G/IIIB 230
Fumaric Acid 110-17-8 G/IIIB M 520
Garlic, Dehydrated G/IIIB NL 360
Gilsonite 12002-43-6 F/IIIB 500
Green Base Harmon Dye G/IIIB 175
Guar Seed G/IIIB NL 500
Gulasonic Acid, Diacetone G/IIIB NL 420
Gum, Arabic G/IIIB 260
Gum, Karaya G/IIIB 240
Gum, Manila G/IIIB CL 360
Gum, Tragacanth 9000-65-1 G/IIIB 260
Hemp Hurd G/IIIB 220
Hexamethylene Tetramine 100-97-0 G/IIIB S 410
Hydroxyethyl Cellulose G/IIIB NL 410
Iron, 98% H2 Reduced E/IIIC 290
Iron, 99% Carbonyl 13463-40-6 E/IIIC 310
Isotoic Anhydride G/IIIB NL 700
L-sorbose G/IIIB M 370
Lignin, Hydrolized, Wood-type, Fine G/IIIB NL 450
Lignite, California F/IIIB 180
Lycopodium G/IIIB 190
Malt Barley G/IIIB 250
Manganese 7439-96-5 E/IIIC 240
Magnesium, Grade B, Milled E/IIIC 430
Manganese Vancide G/IIIB 120
Mannitol 69-65-8 G/IIIB M 460
Methacrylic Acid Polymer G/IIIB 290
Methionine (l-methionine) 63-68-3 G/IIIB 360
Methyl Cellulose G/IIIB 340
Methyl Methacrylate Polymer 9011-14-7 G/IIIB NL 440
Methyl Methacrylate-ethyl Acrylate G/IIIB NL 440
Methyl Methacrylate-styrene-butadiene G/IIIB NL 480
Milk, Skimmed G/IIIB 200
N,N-Dimethylthio-formamide G/IIIB 230
Nitropyridone 100703-82-0 G/IIIB M 430
Nitrosamine G/IIIB NL 270
Nylon Polymer 63428-84-2 G/IIIB 430
Para-oxy-benzaldehyde 123-08-0 G/IIIB CL 380
Paraphenylene Diamine 106-50-3 G/IIIB M 620
Paratertiary Butyl Benzoic Acid 98-73-7 G/IIIB M 560
Pea Flour G/IIIB 260
Peach Pit Shell G/IIIB 210
Peanut Hull G/IIIB 210
Peat, Sphagnum 94114-14-4 G/IIIB 240
Pecan Nut Shell 8002-03-7 G/IIIB 210
Pectin 5328-37-0 G/IIIB 200
Pentaerythritol 115-77-5 G/IIIB M 400
Petrin Acrylate Monomer 7659-34-9 G/IIIB NL 220
Petroleum Coke (More Than 8% Total Entrapped Volatiles) F/IIIB
Petroleum Resin 64742-16-1 G/IIIB 500
Phenol Formaldehyde 9003-35-4 G/IIIB NL 580
Phenol Formaldehyde, Polyalkylene-p 9003-35-4 G/IIIB 290
Phenol Furfural 26338-61-4 G/IIIB 310
Phenylbetanaphthylamine 135-88-6 G/IIIB NL 680
Phthalic Anydride 85-44-9 G/IIIB M 650
Phthalimide 85-41-6 G/IIIB M 630
Pitch, Coal Tar 65996-93-2 F/IIIB NL 710
Pitch, Petroleum 68187-58-6 F/IIIB NL 630
Polycarbonate G/IIIB NL 710
Polyethylene, High Pressure Process 9002-88-4 G/IIIB 380
Polyethylene, Low Pressure Process 9002-88-4 G/IIIB NL 420
Polyethylene Terephthalate 25038-59-9 G/IIIB NL 500
Polyethylene Wax 68441-04-8 G/IIIB NL 400
Polypropylene (no antioxidant) 9003-07-0 G/IIIB NL 420
Polystyrene Latex 9003-53-6 G/IIIB 500
Polystyrene Molding Compound 9003-53-6 G/IIIB NL 560
Polyurethane Foam, Fire Retardant 9009-54-5 G/IIIB 390
Polyurethane Foam, No Fire Retardant 9009-54-5 G/IIIB 440
Polyvinyl Acetate 9003-20-7 G/IIIB NL 550
Polyvinyl Acetate/Alcohol 9002-89-5 G/IIIB 440
Polyvinyl Butyral 63148-65-2 G/IIIB 390
Polyvinyl Chloride-dioctyl Phthalate G/IIIB NL 320
Potato Starch, Dextrinated 9005-25-8 G/IIIB NL 440
Pyrethrum 8003-34-7 G/IIIB 210
Rayon (Viscose) Flock 61788-77-0 G/IIIB 250
Red Dye Intermediate G/IIIB 175
Rice G/IIIB 220
Rice Bran G/IIIB NL 490
Rice Hull G/IIIB 220
Rosin, DK 8050-09-7 G/IIIB NL 390
Rubber, Crude, Hard 9006-04-6 G/IIIB NL 350
Rubber, Synthetic, Hard (33% S) 64706-29-2 G/IIIB NL 320
Safflower Meal G/IIIB 210
Salicylanilide 87-17-2 G/IIIB M 610
Sevin 63-25-2 G/IIIB 140
Shale, Oil 68308-34-9 F/IIIB
Shellac 9000-59-3 G/IIIB NL 400
Sodium Resinate 61790-51-0 G/IIIB 220
Sorbic Acid (Copper Sorbate or Potash) 110-44-1 G/IIIB 460
Soy Flour 68513-95-1 G/IIIB 190
Soy Protein 9010-10-0 G/IIIB 260
Stearic Acid, Aluminum Salt 637-12-7 G/IIIB 300
Stearic Acid, Zinc Salt 557-05-1 G/IIIB M 510
Styrene Modified Polyester-Glass Fiber 100-42-5 G/IIIB 360
Styrene-acrylonitrile (70-30) 9003-54-7 G/IIIB NL 500
Styrene-butadiene Latex (>75% styrene) 903-55-8 G/IIIB NL 440
Styrene-maleic Anhydride Copolymer 9011-13-6 G/IIIB CL 470
Sucrose 57-50-1 G/IIIB CL 350
Sugar, Powdered 57-50-1 G/IIIB CL 370
Sulfur 7704-34-9 G/IIIB 220
Tantalum 7440-25-7 E/IIIC 300
Terephthalic Acid 100-21-0 G/IIIB NL 680
Thorium (contains 1.2% O) 7440-29-1 E/IIIC CL 270
Tin, 96%, Atomized (2% Pb) 7440-31-5 E/IIIC 430
Titanium, 99% Ti 7440-32-6 E/IIIC CL 330
Titanium Hydride (95% Ti, 3.8% H) 7704-98-5 E/IIIC CL 480
Trithiobisdimethylthio-formamide G/IIIB 230
Tung, Kernels, Oil-free 8001-20-5 G/IIIB 240
Urea Formaldehyde Molding Compound 9011-05-6 G/IIIB NL 460
Urea Formaldehyde-phenol Formaldehyde 25104-55-6 G/IIIB 240
Vanadium, 86.4% 7440-62-2 E/IIIC 490
Vinyl Chloride-acrylonitrile Copolymer 9003-00-3 G/IIIB 470
Vinyl Toluene-acrylonitrile Butadiene 76404-69-8 G/IIIB NL 530
Violet 200 Dye G/IIIB 175
Vitamin B1, Mononitrate 59-43-8 G/IIIB NL 360
Vitamin C 50-81-7 G/IIIB 280
Walnut Shell, Black G/IIIB 220
Wheat G/IIIB 220
Wheat Flour 130498-22-5 G/IIIB 360
Wheat Gluten, Gum 100684-25-1 G/IIIB NL 520
Wheat Starch G/IIIB NL 380
Wheat Straw G/IIIB 220
Wood Flour G/IIIB 260
Woodbark, Ground G/IIIB 250
Yeast, Torula 68602-94-8 G/IIIB 260
Zirconium Hydride 7704-99-6 E/IIIC 270
Zirconium (contains 0.3% O) 7440-67-7 E/IIIC CL 330
Notes:
1. Normally, the minimum ignition temperature of a layer of a specific dust is lower than the minimum ignition temperature
of a cloud of that dust. Since this is not universally true, the lower of the two minimum ignition temperatures is listed. If no
symbol appears in the “Code” column, then the layer ignition temperature is shown. “CL” means the cloud ignition
temperature is shown. “NL” means that no layer ignition temperature is available, and the cloud ignition temperature is
shown. “M” signifies that the dust layer melts before it ignites; the cloud ignition temperature is shown. “S” signifies that the
dust layer sublimes before it ignites; the cloud ignition temperature is shown.
2. Certain metal dusts may have characteristics that require safeguards beyond those required for atmospheres containing the
dusts of aluminum, magnesium, and their commercial alloys. For example, zirconium and thorium dusts may ignite
spontaneously in air, especially at elevated temperatures.
3. Due to the impurities found in coal, its ignition temperatures vary regionally and ignition temperatures are not available for
all regions in which coal is mined.
Public Comment No. 15-NFPA 499-2015 [ Chapter 6 ]
Chapter 6 Classification of Combustible Dust Class II (Combustible Dust) or Zone 20, Zone 21, andZone 22 Locations
6.1 General.
6.1.1
The decision to classify an area as hazardous should be based on the probability that a combustible dustcould be present. This action defines the NEC Class II condition Combustible Dust condition. Due to thecomplexity of the processes that create dust, the classification of these hazardous locations should bedetermined by specialists, unless the basis for the classification is simple and straightforward.
Note: Combustible Dust conditions may be identified within the National Electrical Code as HazardousClassified Class II or Zone 20, 21, or Zone 22 locations .
6.1.2
Once the NEC Class II Combustible dust condition has been defined, the next step should be todetermine the degree of hazard — that is, whether the area is Division 1, Division 2, Zone 20, Zone 21,Zone 22 or unclassified.
6.2* Conditions Necessary for Ignition of Combustible Dust.
6.2.1
In a Class II location Combustible Dust location , one of the sets of conditions in 6.2.1.1 through 6.2.1.3must be satisfied for ignition by the electrical installation.
6.2.1.1
In the first set of conditions, the following conditions exist:
(1) A combustible dust is present.
(2) The dust is suspended in the air in the proportions required to produce an ignitible mixture. Further,within the context of this recommended practice, a sufficient quantity of this suspension is present inthe vicinity of the electrical equipment.
(3) There is a source of thermal or electrical energy sufficient to ignite the suspended mixture. Within thecontext of this recommended practice, the energy source is understood to originate with the electricalsystem.
6.2.1.2*
In the second set of conditions, the following conditions exist:
(1) A combustible dust is present.
(2) The dust is layered thickly enough on the electrical equipment to interfere with the dissipation of heatand allow the layer to reach the ignition temperature of the dust.
(3) The external temperature of the electrical equipment is high enough to cause the dust to reach itsignition temperature directly or to dry out the dust and cause it to self-heat.
6.2.1.3
In the third set of conditions, the following conditions exist:
(1) A combustible metal dust ( Group E or Group IIIC) dust is present.
(2) The dust is layered or in suspension in hazardous quantities.
(3) Current through the dust is sufficient to cause ignition.
6.2.2
Once ignition has occurred, either in a cloud suspension or in a layer, an explosion is likely.
6.2.2.1
Often the initial explosion is followed by another much more violent explosion fueled from dustaccumulations on structural beams and equipment surfaces that are thrown into suspension by the initialblast.
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6.2.2.2
For that reason, good housekeeping is vitally important in all areas where dust is handled, and is assumedthroughout this recommended practice.
6.2.3
In classifying a particular location, the presence of a combustible dust is significant in determining thecorrect division.
6.2.3.1
The classification depends both on the presence of dust clouds and on the presence of hazardousaccumulations of dust in layer form.
6.2.3.2
As specified in 5.1.3.1, the presence of a combustible dust cloud under normal conditions of operation ordue to frequent repair or maintenance should be classified as Division 1 or Zone 20/Zone 21 .
6.2.3.3
Abnormal operation of machinery and equipment, which could simultaneously produce a dust cloud orsuspension and a source of ignition, also should be classified as Division 1 or Zone 20/Zone 21 .
6.2.3.4
In other words, if a dust cloud is present at any time, it is assumed to be ignitible, and all that is necessaryfor electrical ignition is failure of the electrical system.
6.2.3.5
If dust clouds or hazardous dust accumulations are present only as a result of infrequent malfunctioning ofhandling or processing equipment, and ignition can result only from abnormal operation or failure ofelectrical equipment, the location should be classified Division 2 or Zone 22 .
6.2.4
The presence of an ignitible dust cloud or an ignitible dust layer is important in determining the boundariesof the hazardous (classified) location.
6.2.5
The quantity of dust, its physical and chemical properties, its dispersion properties, and the location of wallsand cutoffs all must be considered.
6.3 Combustible Dust Class II, Division 1 or Zone 20/Zone 21 Classified Locations.
6.3.1
Where a combustible dust cloud is likely to be present under normal conditions, the location should beclassified as Division 1 or Zone 20/Zone 21 .
6.3.1.1
This practice does not support a design that permits a normal continued condition of more than the testedlayer thickness (see 4.2.3.3 ) of dust accumulation nor presence of greater than moderate isolated dustcloud, external to processing equipment.
6.3.2*
Where a dust layer greater than 3.0 mm ( 1⁄8 in.) thick is present under normal conditions, the locationshould be classified as Division 1 or Zone 20/Zone 21 .
6.3.3
The term normal does not necessarily mean the situation that prevails when everything is working properly.
6.3.3.1
For instance, if a bucket elevator requires frequent maintenance and repair, this repair should be viewed asnormal.
6.3.3.2
If quantities of ignitible dust are released as a result of the maintenance, the location is Division 1 or Zone20/Zone 21 .
6.3.3.3
However, if that elevator is replaced and now repairs are not usually required between turnarounds, theneed for repairs is considered abnormal.
6.3.3.4
The classification of the location, therefore, is related to equipment maintenance, both procedures andfrequencies.
6.3.3.5
Similarly, if the problem is the buildup of dust layers without the presence of visible dust suspensions, goodand frequent cleaning procedures or the lack thereof will influence the classification of the location.
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6.4 Combustible Dust Class II, Division 2 or Zone 22 Classified Locations.
6.4.1
The criterion for a Division 2 or Zone 22 location is whether the location is likely to have ignitible dustsuspensions or hazardous dust accumulations only under abnormal conditions. The term abnormal is usedhere in a limited sense and does not include a major catastrophe.
6.4.2
As an example, consider the replaced bucket elevator of 6.3.3.1, which releases ignitible dust only underabnormal conditions. In this case, there is no Division 1 or Zone 20/Zone 21 location because the elevatoris normally tight. To release dust, the elevator would have to leak, and that would not be normal.
6.4.3
Chemical process equipment does not fail often. Furthermore, the electrical installation requirement of theNEC for Division 2 or Zone 22 locations is such that an ignition-capable spark or hot surface will occur onlyin the event of abnormal operation or failure of electrical equipment. Otherwise, sparks and hot surfaces arenot present or are contained in enclosures. On a realistic basis, the possibility of process equipment andelectrical equipment failing simultaneously is remote.
6.4.4
The Division 2 or Zone 22 classification is applicable to conditions not involving equipment failure. Forexample, consider a location classified as Division 1 because of normal presence of ignitible dustsuspension. Obviously, one side of the Division 1 or Zone 20/Zone 21 boundary cannot be normallyhazardous and the opposite side never hazardous. Similarly, consider a location classified as Division 1 orZone 20/Zone 21 because of the normal presence of hazardous dust accumulations. One side of thedivision boundary cannot be normally hazardous, with thick layers of dust, and the other side unclassified,with no dust, unless there is an intervening wall.
6.4.5
Where there is no wall, a surrounding transition Division 2 location or Zone 22location separates a Division1 or Zone 20/Zone 21 location from an unclassified location. For Group E or Group IIIC combustible metaldusts which may be present in quantities sufficient to be hazardous , the surrounding transition is may beapplied as an additional Division 1 or Zone 20/Zone 21 location or as a Division 2 or Zone 22 either as anextra precaution or as conditions warrant .
6.4.6
Walls are much more important in separating Division 1 and Zone 20/Zone 21 locations from Division 2and Zone 22 and unclassified locations in Class II combustible dust locations than in Class I locations.
6.4.6.1
Only unpierced solid walls make satisfactory barriers in Class I locations, whereas closed doors, lightweightpartitions, or even partial partitions could make satisfactory walls between combustible dust Class II,Division 1 locations or Zone 20/Zone 21locations and unclassified locations.
6.4.6.2
Area classification does not extend beyond the wall, provided it is effective in preventing the passage ofdust in suspension or layer form.
6.5 Unclassified Locations.
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6.5.1
Experience has shown that the release of ignitible dust suspensions from some operations and apparatusis so infrequent that area classification is not necessary. For example, where combustible dusts areprocessed, stored, or handled, it is usually not necessary to classify the following locations:
(1) Where materials are stored in sealed containers (e.g., bags, drums, or fiber packs on pallets or racks)
(2) Where materials are transported in well-maintained closed piping systems
(3) Where palletized materials with minimal dust are handled or used
(4) Where closed tanks are used for storage and handling
(5) Where dust removal systems prevent the following:
(6) Visual dust clouds
(7) Layer accumulations that make surface colors indiscernible (see A.6.3.2 )
(8) Where excellent housekeeping prevents the following:
(9) Visual dust clouds
(10) Layer accumulations that make surface colors indiscernible (see A.6.3.2 )
6.5.2
Dust removal systems that are provided to allow an unclassified location should have adequate safeguardsand warnings against failure.
6.5.3
Open flames and hot surfaces associated with the operation of certain equipment, such as boilers and firedheaters, provide inherent thermal ignition sources.
6.5.3.1
Area classification is not appropriate in the immediate vicinity of inherent thermal ignition sources.
6.5.3.2
Dust-containing operations should be cut off by blank walls or located away from inherent thermal ignitionsources.
6.5.3.3
Where pulverized coal or ground-up solid waste is used to fire a boiler or incinerator, it is prudent to avoidinstalling electrical equipment that could become primary ignition sources for leaks in the fuel feed lines.
6.6 Procedure for Classifying Areas.
Subsections 6.6.1 through 6.6.4 detail the procedure that should be used for each room, section, or areabeing classified.
6.6.1 Step 1: Need for Classification.
The area should be classified if a combustible material is processed, handled, or stored there.
6.6.2 Step 2: Gathering Information.
6.6.2.1 Proposed Facility Information.
For a proposed facility that exists only in drawings, a preliminary area classification can be done so thatsuitable electrical equipment and instrumentation can be purchased. Plants are rarely built exactly as thedrawings portray, and the area classification should be modified later, based on the actual facility.
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6.6.2.2 Existing Facility History.
For an existing facility, the individual plant experience is extremely important in classifying areas within theplant. Both operation and maintenance personnel in the actual plant should be asked the followingquestions:
(1) Is a dust likely to be in suspension in air continuously, periodically, or intermittently under normalconditions in quantities sufficient to produce an ignitible mixture?
(2) Are there dust layers or accumulations on surfaces deeper than 3.0 mm ( 1⁄8 in.)?
(3) Are there dust layers or accumulations on surfaces that make the colors of the floor or equipmentsurfaces indiscernible?
(4) What is the dust accumulation after 24 hours?
(5) Is the equipment in good condition, in questionable condition, or in need of repair? Are equipmentenclosures in good repair, and do they prevent the entrance of dust?
(6) Do maintenance practices result in the formation of ignitible mixtures?
(7) What equipment is used for dust collection?
6.6.2.3 Material Density.
The specific particle density of the dust should be determined if it is at least 641 kg/m3 (40 lb/ft3).
6.6.2.4 Plot Plan.
A plot plan (or similar drawing) is needed that shows all vessels, tanks, building structures, partitions, andsimilar items that would affect dispersion or promote accumulation of the dust.
6.6.2.5 Fire Hazard Properties of Combustible Material.
The NEC group and the layer or cloud ignition temperature are shown in Table 5.2.2 for many materials.
6.6.2.5.1
A material could be listed in Table 5.2.2 under a chemical name different from the chemical name used atthe facility.
Table 5.2.3 is provided to cross-reference the CAS number of the material to the chemical name used inTable 5.2.2.
6.6.2.5.2
Where materials being used are not listed in Table 5.2.2 or in other reputable chemical references, theinformation needed to classify the area can be obtained by one of the following methods:
(1) Contacting the material supplier to determine if the material has been group classified and if theautoignition temperature has been determined
(2) Having the material evaluated for the group and tested for the autoignition temperature
6.6.3 Step 3: Selecting the Appropriate Classification Diagram.
The appropriate diagrams should be selected based on the following:
(1) Whether the process equipment is open or enclosed
(2) Whether the dust is Group E, F, or G, or Group IIIC, or IIIB.
(3) Whether the area is for storage
6.6.4 Step 4: Determining the Extent of the Hazardous (Classified) Location.
The extent of the hazardous (classified) location can be determined using sound engineering judgment toapply the methods discussed in Section 5.1 and the diagrams contained in this chapter.
6.6.4.1
The potential sources of leaks should be located on the plan drawing or at the actual location. Thesesources of leaks could include rotating or reciprocating shafts, doors and covers on process equipment,and so forth.
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6.6.4.2
For each leakage source, an equivalent example on the selected classification diagram should be locatedto determine the minimum extent of classification around the leakage source. The extent can be modifiedby considering the following:
(1) Whether an ignitible mixture is likely to occur frequently due to repair, maintenance, or leakage
(2) Where conditions of maintenance and supervision are such that leaks are likely to occur in processequipment, storage vessels, and piping systems containing combustible material
(3) Ventilation or prevailing wind in the specific area and the dispersion rates of the combustible materials
6.6.4.3
Once the minimum extent is determined, for practical reasons distinct landmarks (e.g., curbs, dikes, walls,structural supports, edges of roads) should be utilized for the actual boundaries of the area classification.Landmarks permit identification of the boundaries of the hazardous (classified) locations for electricians,instrument technicians, operators, and other personnel.
6.7* Housekeeping.
Housekeeping frequency (see Table A.6.7) and effectiveness are significant factors in the presence andcontrol of dust accumulations.
6.8 Extent of Hazardous (Classified) Locations.
6.8.1 General.
Careful consideration of the following factors is necessary in determining the extent of the locations:
(1) Combustible material involved
(2) Bulk density of the material
(3) Particle sizes of the material
(4) Particle density
(5) Process or storage pressure
(6) Size of the leak opening
(7) Quantity of the release
(8) Dust removal system
(9) Housekeeping
(10) Presence of any hybrid mixture
6.8.2
The dispersal of dusts and the influence of the factors in 6.8.1 on this dispersal are discussed generally in4.1.3. The importance of dust removal and housekeeping are discussed in other paragraphs of thischapter.
6.8.3
In addition, walls, partitions, enclosures, or other barriers and strong air currents will also affect the distancethat dust particles will travel and the extent of the Division 1 or Zone 20/Zone 21 and Division 2 or Zone 22locations.
6.8.4
Where there are walls that limit the travel of the dust particles, area classifications do not extend beyondthe walls. Providing walls and partitions is a primary means of limiting the extent of hazardous (classified)locations.
6.8.5
Where effective walls are not provided, the extent of the Division 1 or Zone 20/Zone 21 and Division 2 orZone 22 locations can be estimated as follows:
(1) By visual observation of the existing location using the guidelines in A.6.3.2
(2) By experience with similar dusts and similar operations and by taking into consideration differences inequipment, enclosures, dust-removal systems, and housekeeping rules and methods
(3) By using the classification diagrams in this chapter
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6.8.6
Tight equipment, ventilated hoods and pickup points, good maintenance, and good housekeeping practicesshould limit Division 1 locations to those inside process enclosures and equipment and those close toopenings necessary for transfer of material, as from conveyors to grinders to storage bins to bags. Similarly,the same factors will also limit the Division 2 and Zone 22 location surrounding the Division 1 or Zone20/Zone 21 location.
6.8.7
The size of a building and its walls will influence the classification of the enclosed volume. In the case of asmall room, it can be appropriate to classify the entire volume as Division 1 or Zone 20/Zone 21 or Division2 or Zone 22 .
6.8.8
When classifying large buildings, careful evaluation of prior experience with the same or similarinstallations should be made. Where experience indicates that a particular design concept is sound, thatdesign should continue to be followed. Sound engineering judgment and good housekeeping should beused to minimize the extent of hazardous (classified) locations.
6.8.8.1
Wherever possible with large buildings, walls should be used to cut off dusty operations to minimize thehazardous (classified) location. Where walls are not possible, the concentric volume approach of a Division1 or Zone 20/Zone 21 location surrounded by a larger Division 2 or Zone 22 location, should be used asshown in the diagrams in Section 6.10. See Figure 6.10(a) .
6.8.8.2
Where it is necessary to have a number of dusty operations located in a building, there could be amultiplicity of Division 1 or Zone 20/Zone 21 locations, with intervening Division 2 or Zone 22 andunclassified locations.
6.8.9
The quantity of dust released and its distance of travel are of extreme importance in determining the extentof a hazardous (classified) location. This determination requires sound engineering judgment. However,one cannot lose sight of the purpose of this judgment; the location is classified solely for the installation ofelectrical equipment.
6.9 Discussion of Diagrams and Recommendations.
6.9.1
The series of diagrams in Section 6.10 illustrate how typical dusty areas should be classified and therecommended extent of classification.
6.9.2
The diagrams should be used as aids in developing electrical classification maps of operating units, storageareas, and process buildings. Most of the maps will be plan views. However, elevations could be necessaryto provide the three-dimensional picture of an actual operation.
6.9.3
An operating unit could have many interconnected sources of combustible material, such as storage tanks,bins and silos, piping and ductwork, hammer mills, ball mills, grinders, pulverizers, milling machines,conveyors, bucket elevators, and bagging or other packaging machines. These in turn present sources ofleaks, such as flanged and screwed connections, fittings, openings, valves, and metering and weighingdevices. Thus, actual diagrams of the equipment could be required so that the necessary engineeringjudgment to establish the boundaries of Division 1 or Zone 20/Zone 21 and Division 2 or Zone 22 locationscan be applied.
6.9.4
These diagrams apply to operating equipment processing dusts when the specific particle density is greater
than 641 kg/m3 (40 lb/ft3). When dusts with a specific particle density less than 641 kg/m3 (40 lb/ft3) arebeing handled, there is a pronounced tendency for the fine dust to drift on air currents normally present inindustrial plants for distances considerably farther than those shown on these diagrams. In those cases, itwill be necessary to extend the hazardous (classified) location using sound engineering judgment andexperience.
6.9.5
Good engineering practices, good housekeeping practices, and effective dust removal systems arenecessary to limit the extent of the classified areas and to minimize the chances of primary explosions andsecondary explosions, which are often more violent.
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6.10 Classification Diagrams.
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The classification diagrams shown in Figure 6.10(a) through Figure 6.10(i) assume that the specific
particle density is greater than 641 kg/m3 (40 lb/ft3).
Figure 6.10(a) Group F or Group G Dust — Indoor, Unrestricted Area; Open or Semi-EnclosedOperating Equipment.
Figure 6.10(b) Group E Dust — Indoor, Unrestricted Area; Open or Semi-Enclosed OperatingEquipment.
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Figure 6.10(c) Group F or Group G Dust — Indoor, Unrestricted Area; Operating EquipmentEnclosed; Area Classified as a Class II, Division 2 Location.
Figure 6.10(d) Group F or Group G Dust — Indoor, Unrestricted Area; Operating EquipmentEnclosed; Area is an Unclassified Location.
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Figure 6.10(e) Groups E, F, or G Dusts — Storage Area Bags, Drums, or Closed Hoppers.
Figure 6.10(f) Group E Dust — Indoor, Walled-Off Area; Operating Equipment Enclosed.
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Figure 6.10(g) Group F or Group G Dust — Indoor, Walled-Off Area; Operating Equipment Open orSemi-Enclosed.
Figure 6.10(h) Group F or Group G Dust — Indoor, Walled-Off Area; Multiple Pieces of OperatingEquipment.
Figure 6.10(i) Group F or Group G Dust — Indoor, Unrestricted Area; Ventilated Bagging Head.
Statement of Problem and Substantiation for Public Comment
Revisions reflect the application of current combustible dust Class- Division methodology with the combustible dust Zone methodology.
Related Public Comments for This Document
Related Comment Relationship
Public Comment No. 1-NFPA 499-2015 [Section No. 1.2] Zone methodology
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Related Item
Public Input No. 5-NFPA 499-2013 [Chapter 4]
Submitter Information Verification
Submitter Full Name: David Wechsler
Organization: [ Not Specified ]
Street Address:
City:
State:
Zip:
Submittal Date: Tue Mar 17 10:08:44 EDT 2015
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Public Comment No. 12-NFPA 499-2015 [ Section No. 6.3 ]
6.3 Class II, Division 1 or Zone 20/21 Classified Locations.
6.3.1
Where a combustible dust cloud is likely to be present under normal conditions, the location should beclassified as Division 1 or using the zone methodolgy Zone 20 or Zone 21 .
6.3.1.1
This practice does not support a design that permits a normal continued condition of more than the testedlayer thickness (see 4.2.3.3 ) of dust accumulation nor presence of greater than moderate isolated dustcloud, external to processing equipment.
6.3.2*
Where a dust layer greater than 3.0 mm ( 1⁄8 in.) thick is present under normal conditions, the locationshould be classified as Division 1 1 or using the zone methodology, Zone 20 or Zone 21 .
6.3.3
The term normal does not necessarily mean the situation that prevails when everything is working properly.
6.3.3.1
For instance, if a bucket elevator requires frequent maintenance and repair, this repair should be viewed asnormal.
6.3.3.2
If quantities of ignitible dust are released as a result of the maintenance, the location is Division 1, orusing the zone methodology, Zone 20 or Zone 21 .
6.3.3.3
However, if that elevator is replaced and now repairs are not usually required between turnarounds, theneed for repairs is considered abnormal.
6.3.3.4
The classification of the location, therefore, is related to equipment maintenance, both procedures andfrequencies.
6.3.3.5
Similarly, if the problem is the buildup of dust layers without the presence of visible dust suspensions, goodand frequent cleaning procedures or the lack thereof will influence the classification of the location.
Statement of Problem and Substantiation for Public Comment
To agree with the insertion of the Zone documentation
Related Public Comments for This Document
Related Comment Relationship
Public Comment No. 1-NFPA 499-2015 [Section No. 1.2] Zone material
Public Comment No. 5-NFPA 499-2015 [Section No. 5.2.2] Zone material
Related Item
Public Input No. 5-NFPA 499-2013 [Chapter 4]
Submitter Information Verification
Submitter Full Name: David Wechsler
Organization: [ Not Specified ]
Street Address:
City:
State:
Zip:
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Submittal Date: Mon Mar 16 11:18:54 EDT 2015
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Public Comment No. 13-NFPA 499-2015 [ Section No. 6.4 ]
6.4 Class II, Division 2 or Zone 22 Classified Locations.
6.4.1
The criterion for a Class II, Division 2 or a Zone 22 location is whether the location is likely to have ignitibledust suspensions or hazardous dust accumulations only under abnormal conditions. The term abnormal isused here in a limited sense and does not include a major catastrophe.
6.4.2
As an example, consider the replaced bucket elevator of 6.3.3.1, which releases ignitible dust only underabnormal conditions. In this case, there is no Division 1 location because the elevator is normally tight. Torelease dust, the elevator would have to leak, and that would not be normal.
6.4.3
Chemical process equipment does not fail often. Furthermore, the electrical installation requirement of theNEC for Class II, Division 2 or Zone 22 locations is such that an ignition-capable spark or hot surface willoccur only in the event of abnormal operation or failure of electrical equipment. Otherwise, sparks and hotsurfaces are not present or are contained in enclosures. On a realistic basis, the possibility of processequipment and electrical equipment failing simultaneously is remote.
6.4.4
The Class II, Division 2 and the Zone 22 classification is applicable to conditions not involving equipmentfailure. For example, consider a location classified as Division 1 because of normal presence of ignitibledust suspension. Obviously, one side of the Division 1 boundary cannot be normally hazardous and theopposite side never hazardous. Similarly, consider a location classified as Division 1 because of the normalpresence of hazardous dust accumulations. One side of the division boundary cannot be normallyhazardous, with thick layers of dust, and the other side unclassified, with no dust, unless there is anintervening wall.
6.4.5
Where there is no wall, a surrounding transition Class II, Division 2 or Zone 22 location separates a ClassII, Division 1 or Zone 20/21 location from an unclassified location. For Group E, the surrounding transitionis an additional Division 1 location (See A.6.3. for Group IIIC materials) .
6.4.6
Walls are much more important in separating Class II, Division 1 or Zone 20/21 locations from Class II,Division 2 or Zone 22 and unclassified locations in Class II locations than in Class I locations.
6.4.6.1
Only unpierced solid walls make satisfactory barriers in Class I locations, whereas closed doors, lightweightpartitions, or even partial partitions could make satisfactory walls between Class II, Division 1 or Zone20/21 locations and unclassified locations.
6.4.6.2
Area classification does not extend beyond the wall, provided it is effective in preventing the passage ofdust in suspension or layer form.
Statement of Problem and Substantiation for Public Comment
Revisions needed to correlate with Zone information.
Related Public Comments for This Document
Related Comment Relationship
Public Comment No. 1-NFPA 499-2015 [Section No. 1.2]
Related Item
Public Input No. 5-NFPA 499-2013 [Chapter 4]
Submitter Information Verification
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Submitter Full Name: David Wechsler
Organization: [ Not Specified ]
Street Address:
City:
State:
Zip:
Submittal Date: Mon Mar 16 11:30:30 EDT 2015
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Public Comment No. 14-NFPA 499-2015 [ Section No. 6.6.3 ]
6.6.3 Step 3: Selecting the Appropriate Classification Diagram.
The appropriate diagrams should be selected based on the following:
(1) Whether the process equipment is open or enclosed
(2) Whether the dust is Class II, Group E, F, or G, or for Zones, Group IIIC or IIIB.
(3) Whether the area is for storage
Statement of Problem and Substantiation for Public Comment
To correlate with Zone material
Related Public Comments for This Document
Related Comment Relationship
Public Comment No. 1-NFPA 499-2015 [Section No. 1.2] Zone information
Related Item
Public Input No. 5-NFPA 499-2013 [Chapter 4]
Submitter Information Verification
Submitter Full Name: David Wechsler
Organization: [ Not Specified ]
Street Address:
City:
State:
Zip:
Submittal Date: Mon Mar 16 11:40:30 EDT 2015
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Public Comment No. 9-NFPA 499-2015 [ Section No. 6.7 ]
6.7* Housekeeping.
Housekeeping frequency (see Tables A.6.7 a and Table A.6.7 b ) and effectiveness are significant factorsin the presence and control of dust accumulations.
Statement of Problem and Substantiation for Public Comment
Revision needed to support inclusion of Combustible Dust Zones.
Related Public Comments for This Document
Related Comment Relationship
Public Comment No. 1-NFPA 499-2015 [Section No. 1.2]
Public Comment No. 2-NFPA 499-2015 [New Section after 4.3]
Public Comment No. 4-NFPA 499-2015 [New Section after 5.2.1]
Public Comment No. 5-NFPA 499-2015 [Section No. 5.2.2]
Public Comment No. 6-NFPA 499-2015 [Section No. 6.10]
Public Comment No. 10-NFPA 499-2015 [Section No. A.6.3.2]
Public Comment No. 11-NFPA 499-2015 [Section No. A.6.7]
Related Item
Public Input No. 30-NFPA 499-2014 [New Section after 5.1.4]
Submitter Information Verification
Submitter Full Name: David Wechsler
Organization: [ Not Specified ]
Street Address:
City:
State:
Zip:
Submittal Date: Mon Mar 16 10:31:29 EDT 2015
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Public Comment No. 6-NFPA 499-2015 [ Section No. 6.10 ]
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6.10 Classification Diagrams.
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Revise sentence
The classification diagrams shown in Figure 6.10(a) through Figure 6.10(i) and Figure 6.11(a) through
Figure 6.11(I) assume that the specific particle density is greater than 641 kg/
m 3
m3 (40 lb/
ft 3
ft3 ).
Figure 6.10(a) Group F or Group G Dust — Indoor, Unrestricted Area; Open or Semi-EnclosedOperating Equipment.
Figure 6.10(b) Group E Dust — Indoor, Unrestricted Area; Open or Semi-Enclosed OperatingEquipment.
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Figure 6.10(c) Group F or Group G Dust — Indoor, Unrestricted Area; Operating EquipmentEnclosed; Area Classified as a Class II, Division 2 Location.
Figure 6.10(d) Group F or Group G Dust — Indoor, Unrestricted Area; Operating EquipmentEnclosed; Area is an Unclassified Location.
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Figure 6.10(e) Groups E, F, or G Dusts — Storage Area Bags, Drums, or Closed Hoppers.
Figure 6.10(f) Group E Dust — Indoor, Walled-Off Area; Operating Equipment Enclosed.
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Figure 6.10(g) Group F or Group G Dust — Indoor, Walled-Off Area; Operating Equipment Open orSemi-Enclosed.
Figure 6.10(h) Group F or Group G Dust — Indoor, Walled-Off Area; Multiple Pieces of OperatingEquipment.
Figure 6.10(i) Group F or Group G Dust — Indoor, Unrestricted Area; Ventilated Bagging Head.
Additional Proposed Changes
File Name Description Approved
499_work_figs_dbw03102015.pdf replacement figures
Statement of Problem and Substantiation for Public Comment
With the inclusion of Combustible Zone Dusts, these new classification examples, provide correlation with the Division figures which exist in this document.
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Figure 6.10 (f) contains an elevation which does not correctly agree with the figure plan view. Rather than correcting the elevation, which serves little additional purpose and other figures do not have elevations, the elevation should be deleted.
Related Public Comments for This Document
Related Comment Relationship
Public Comment No. 1-NFPA 499-2015 [Section No. 1.2] Supporting Zone Methodology
Public Comment No. 2-NFPA 499-2015 [New Section after 4.3] Supporting Zone Methodology
Public Comment No. 3-NFPA 499-2015 [New Section after 5.1.4] Supporting Zone Methodology
Public Comment No. 4-NFPA 499-2015 [New Section after 5.2.1] Supporting Zone Methodology
Public Comment No. 5-NFPA 499-2015 [Section No. 5.2.2] Supporting Zone Methodology
Public Comment No. 9-NFPA 499-2015 [Section No. 6.7]
Related Item
Public Input No. 26-NFPA 499-2014 [Section No. 6.10]
Submitter Information Verification
Submitter Full Name: David Wechsler
Organization: [ Not Specified ]
Street Address:
City:
State:
Zip:
Submittal Date: Thu Mar 05 11:30:34 EST 2015
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Revise as shown in red For consistency with NFPA 497 figures 5.xx, use convention of ft (m) as follows:
Change from ‘6.1 m (20 ft)’ to ‘20 ft (6.1 m)’
from ‘3.05 m (10 ft)’ to ‘10 ft (3.05 m)’
Revise as shown in red For consistency with NFPA 497 figures 5.xx, use convention of ft (m) as follows:
Change from ‘6.1 m (20 ft)’ to ‘20 ft (6.1 m)’
from ‘3.05 m (10 ft)’ to ‘10 ft (3.05 m)’
Revise as shown in red For consistency with NFPA 497 figures 5.xx, use convention of ft (m) as follows:
Change from ‘3.05 m (10 ft)’ to ‘10 ft (3.05 m)’
No changes proposed
No changes proposed
Div. 1 – 3 ft (915 mm) Div. 2 – See Note
Open door or frequently opened door
Self-closing door kept closed
Revise as shown in red – Remove elevation view
X
Source
Wall or partition With all openings kept closed.
(new) Note: Group E combustible dusts which may be present in quantities sufficient to be hazardous are considered Class II, Division 1 locations per NEC 500.5 (C) (1) . A Class II, Division 2 location may be applied either as an extra precaution or as conditions warrant.
Action: For consistency with NFPA 497 figures 5.xx, use convention of ft (m)
Open door or frequently opened door
Div. 1 – 3 ft (915 mm) Div. 2 – 10 ft (3.05 m)
Revise as shown in red For consistency with NFPA 497 figures 5.xx, use convention of ft (m) as follows:
Self-closing door kept closed
Div. 2 10 ft (3.05 m)
Open door or frequently opened door
Revise as shown in red/blue For consistency with NFPA 497 figures 5.xx, use convention of ft (m) as follows:
Change from ‘6.1 m (20 ft)’ to ‘20 ft (6.1 m)’
from ‘3.05 m (10 ft)’ to ‘10 ft (3.05 m)’
Revise as shown in red For consistency with NFPA 497 figures 5.xx, use convention of ft (m) as follows:
Change from ‘3.05 m (10 ft)’ to ‘10 ft (3.05 m)’
Figure 6.11 (a) Zone Group IIIB Dust – Indoor, Unrestricted Area; Open or Semi-Enclosed Operating Equipment
Zone 21 Zone 22
Zone 22 Zone 21
For consistency with NFPA 497 figures 5.xx, use convention of ft (m) as follows:
Change from ‘6.1 m (20 ft)’ to ‘20 ft (6.1 m)’
from ‘3.05 m (10 ft)’ to ‘10 ft (3.05 m)’
Revise as new figure
20 ft (6.1 m)
Zone 20/Zone 21 Zone 22
Figure 6.11 (b) Zone Group IIIC Dust – Indoor, Unrestricted Area; Open or Semi-Enclosed Operating Equipment
Zone 20/Zone 21 Zone 21/Zone 22
Zone 21
Zone 21 10 ft (3.05 m) 10 ft (3.05 m)
For consistency with NFPA 497 figures 5.xx, use convention of ft (m) as follows: Revise as new figure
Figure 6.11 (c) Zone Group IIIB Dust – Indoor, Unrestricted Area; Operating Equipment Enclosed; Area Classified as a Class II, Zone 22 Location
Zone 21
Zone 21
Zone 22
Zone 22
10 ft (3.05 m)
For consistency with NFPA 497 figures 5.xx, use convention of ft (m) as follows:
Change from ‘3.05 m (10 ft)’ to ‘10 ft (3.05 m)’
Revise as new figure
Zone 21 Zone 22
Figure 6.11 (d) Zone Group IIIB Dust – Indoor, Unrestricted Area; Operating Equipment Enclosed; Area is an Unclassified Location
Revise as new figure
Figure 6.11 (e) Zone Group IIIC or IIIB Dust – Storage Area; Bags, Drums or Closed Hoppers.
Zone 21 Zone 22
Revise as new figure
Zone 20/21 – 3 ft (915 mm) Zone 22 – See Note
Open door or frequently opened door
Self-closing door kept closed
X
Source
Wall or partition With all openings kept closed.
Note: Combustible metal dusts which may be present in quantities sufficient to be hazardous are considered Class II, Division 1 locations per NEC 500.5 (C) (1) and the NEC defines Group IIIC combustible dusts as combustible metal dusts. These are Zone 20/21 locations. A Zone 22 location may be applied to Group IIIC combustible metal dust either as an extra precaution or as conditions warrant.
For consistency with NFPA 497 figures 5.xx, use convention of ft (m)
Revise as new figure
Zone 20/ Zone 21
Figure 6.11 (f) Zone Group IIIC Dust – Indoor, Walled-Off Area; Operating Equipment Enclosed;
Zone 22
Minimize Zone 20/21 cutoff volume and area
Open door or frequently opened door
Zone 21 - 3 ft (915 mm) Zone 22 – 10 ft (3/05 m)
Figure 6.11 (g) Zone Group IIIB Dust – Indoor, Walled-Off Area; Operating Equipment Open or Semi- Enclosed
Zone 21 Zone 22
Zone 21 Zone 22
Revise as new figure
Self-closing door kept closed
Zone 22 10 ft (3.05 m)
Open door or frequently opened door
Figure 6.11 (h) Zone Group IIIB Dust – Indoor, Walled-Off Area; Multiple Pieces of Operating Equipment
Zone 21 Zone 22
Zone 22 Zone 21
20 ft (6.1 m)
Revise as new figure
Figure 6.11 (i) Zone Group IIIB Dust – Indoor, Unrestricted Area; Ventilated Bagging Head
Zone 21 Zone 22
Zone 22 Zone 21
10 ft (3.05 m) 10 ft (.053 m)
10 ft (3 .05 m ) 10 ft (3.05m)
Revise as new figure
Public Comment No. 8-NFPA 499-2015 [ Section No. A.5.1.9 ]
A.5.1.9
Areas that would otherwise be classified as Division 2 due to dust accumulation or release potential areclassified as Division 1 where Group E dusts are present in quantities sufficient to be hazardous. In Figure6.10(a) through Figure 6.10(i) , these areas are denoted as additional Division 1 locations.
Statement of Problem and Substantiation for Public Comment
Action under comment was to delete original statement to agree with 5.1.3.1 (3) and the NEC.
Related Public Comments for This Document
Related Comment Relationship
Public Comment No. 7-NFPA 499-2015 [Section No. 5.1.9]
Related Item
First Revision No. 5-NFPA 499-2014 [Section No. 5.1.9]
Submitter Information Verification
Submitter Full Name: David Wechsler
Organization: [ Not Specified ]
Street Address:
City:
State:
Zip:
Submittal Date: Tue Mar 10 09:06:21 EDT 2015
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Public Comment No. 10-NFPA 499-2015 [ Section No. A.6.3.2 ]
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A.6.3.2
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Generally speaking, the NEC indicates that an area is a Division 1 location if either of the followingconditions exists:
(1) There are explosive dust clouds under normal operating conditions.
(2) Explosive dust clouds can be produced at the same time that a source of ignition is produced.
The dust described in condition (2) can be provided directly by some malfunction of machinery orequipment or by accumulations of dust that are thrown into the air. Presumably, if all the dust on all thesurfaces in a room is sufficient to produce a dust concentration above the minimum explosibleconcentration, then that quantity of dust should define a Division 1 location.
From a practical point of view, a room with a concentration of dust that is above the minimum explosibleconcentration [condition (1)] would result in an atmosphere so dense that visibility beyond 0.9 m to 1.5 m (3ft to 5 ft) would be impossible. Such a condition is unacceptable under today's standards for chemical plantworkplaces. If such a situation were to exist, accumulations on horizontal surfaces would build up veryrapidly.
On the other hand, working back from dust layers on horizontal surfaces in a room to a minimum explosibleconcentration in the room, based on laboratory dust explosion tests, would show a very thin layer of dust,on the order of 3.0 mm ( 1⁄8 in.), to be hazardous. This is an equally impractical answer, because one of themost difficult experimental problems in dust explosion test work is to obtain a reasonably uniform cloud forignition. As a result, the test apparatus is designed specifically to obtain uniform dust distribution. For dustlying on horizontal surfaces in a room or factory to attain such an efficient uniform distribution during anupset condition obviously is impossible.
A typical calculation considers cornstarch with a powder bulk density of approximately 400 kg/m3 (25
lb/ft3). The minimum explosible concentration is 40 g/m3 (0.04 oz/ft3). In a room 3.05 m high × 3.05 m wide× 3.05 m long (10 ft high × 10 ft wide × 10 ft long), the depth of dust that would accumulate on the floor ifthe room were completely filled with a cornstarch cloud at the minimum explosible concentration can becalculated as follows:
For SI units:
[A.6.3.2a]
For inch-pound units:
[A.6.3.2b]
Evenly distributed over 9.3 m2 (100 ft2), the depth of dust would be as follows:
For SI units:
[A.6.34.2c]
For inch-pound units:
[A.6.3.2d]
Theoretically, throwing this amount of dust from the floor and ledges into the room volume would create ahazardous condition. Accomplishing such a feat, even experimentally, would be virtually impossible.
The optimum concentration is that in which the maximum rate of pressure rise is obtained under testconditions. Because the optimum concentration is far higher than the minimum explosible concentration,the layer thicknesses necessary to produce an optimum concentration range from 1.9 mm to 12.7 mm(0.075 in. to 0.5 in.). There is then much more dust available to be thrown into uniform suspension withoutpostulating a 100 percent efficiency of dispersal and distribution. In addition, a number of factors such asparticle size and shape, moisture content, uniformity of distribution, and so on negatively affect thesusceptibility of a dust to ignition. Thus, dusts encountered in industrial plants tend to be less susceptible to
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ignition than those used in the laboratory to obtain explosion concentration data. The classifications ofareas in accordance with Table A.6.3.2(a) and Table A.6.3.2 (b) are recommended, based on a buildup ofthe dust level in a 24-hour period on the major portions of the horizontal surfaces.
Table A.6.3.2(a) Division Class II - Division Determination Guidelines Based on Dust Layer Thickness
Thickness of Dust Layer Classification
>3.0 mm ( 1⁄8 in.) Division 1
<3.0 mm ( 1⁄8 in.), but surface color not discernible Division 2
Surface color discernible under the dust layer Unclassified
Based on these thicknesses of dust, good housekeeping can determine the difference between aclassification of Division 1 and a classification of Division 2 and between a classification of Division 2 andunclassified. It should be emphasized, however, that housekeeping is a supplement to dust sourceelimination and ventilation. It is not a primary method of dust control.
Table A.6.3.2 (b) shows Zone Determination Guidelines Based on Dust Layer Thickness
(see table added as graphic)
{renumber Table A.6.3.2 (b) to A.6.3.2 (c)}
Table A.6.3.2 (c) shows the theoretical thickness of dust on the floor of a 3.05 m × 3.05 m × 3.05 m (10 ft× 10 ft × 10 ft) room necessary to satisfy the concentration requirements for a uniform dust cloud ofminimum explosible concentration and for a uniform dust cloud of optimum concentration for four dusts.
Table A.6.3.2 (b c ) Dust Thickness
MinimumConcentration
Depth ofDust
OptimumConcentration
Depth ofDust
BulkDensity
Material g/m3 oz/ft3 cm in. g/m3 oz/ft3 cm in. kg/m3 lb/ft3
Cornstarch 1.13 0.04 0.03 0.012 14.2 0.5 0.38 0.15 11–23 25–50
Cork 0.99 0.035 0.05 0.022 5.7 0.2 0.32 0.125 5–7 12–15
Sugar 1.28 0.045 0.02 0.0068 14.2 0.5 0.19 0.075 23–25 50–55
Wood flour 0.99 0.035 0.04 0.016 28.4 1.0 1.19 0.47 7.3–16 16–36
Polyethylene(low density)
0.57 0.020 0.02 0.0072 14.2 0.5 0.46 0.18 9.5–15.9 21–35
Additional Proposed Changes
File Name Description Approved
Table_A.6.3.2_b_zones_new.docx new Table A.6.3.2 (b) for Combustible dust Zones
Statement of Problem and Substantiation for Public Comment
To provide proper correlation with the inclusion of Combustible Dust Zones following design/evaluation based currently applied to Class II- Division methodology.
Related Public Comments for This Document
Related Comment Relationship
Public Comment No. 1-NFPA 499-2015 [Section No. 1.2] Zone material
Public Comment No. 9-NFPA 499-2015 [Section No. 6.7] Zone material
Public Comment No. 11-NFPA 499-2015 [Section No. A.6.7]
Related Item
Public Input No. 30-NFPA 499-2014 [New Section after 5.1.4]
Submitter Information Verification
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Submitter Full Name: David Wechsler
Organization: [ Not Specified ]
Street Address:
City:
State:
Zip:
Submittal Date: Mon Mar 16 10:43:13 EDT 2015
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Table A.6.3.2 (b) for Zones1
Thickness of Dust Layer Classification
>3.0 mm (1/8 in.) Zone 20 or Zone 21
<3.0 mm (1/8 in. ) Zone 21 or Zone 22
Surface color discernible under the dust layer or
combustible metal dust is not in a hazardous quantity
Zone 22 or Unclassified.
1 Combustible metal dusts which may be present in quantities sufficient to be hazardous are considered Class II, Division 1 locations per NEC 500.5 (C) (1). The NEC defines Group IIIC combustible dusts as combustible metal dusts. These are Zone 20/21 locations. A Zone 22 location may be applied to Group IIIC combustible metal dusts either as an extra precaution or as conditions warrant.
Public Comment No. 11-NFPA 499-2015 [ Section No. A.6.7 ]
A.6.7
Table A.6.7a and Table A.6. 7 b lists the recommended frequency of housekeeping for combustible dusts.
Table A.6.7 a and Table A.6.7 b criteria should be applied as follows: Given the condition in (1), whichshould then be correctly paired with the defined hazardous area classification shown in (2), this would yielda suggested release frequency and housekeeping activity as addressed in (3) and (4).
Table A.6.7 Recommended 7 a Class II- Division Recommended Frequency of Housekeeping
Depth of DustAccumulation on
Equipment
(1)
Area
Classification
(2)
Release
Frequency
(3)
Housekeeping
Activity
(4)
Negligible, up to <1 mm ( 1⁄32
in.)Unclassified Infrequent Clean as appropriate
Up to 3 mm ( 1⁄8 in.) Class II, Division 2 InfrequentClean as necessary to maintain less than3 mm ( 1⁄8 in.)
Up to 3 mm ( 1⁄8 in.) oroccasional cloud formation
Class II, Division 1or Division 2
OccasionalClean at frequency appropriate tominimize additional dust accumulations orformation of a cloud
>3 mm ( 1⁄8 in.) to layer testvalue, or presence of dustcloud
Class II, Division 1Continuous/
frequently
Clean at frequency appropriate tominimize additional dust accumulations
Exceeds layer test value, orpresence of extensive dustcloud
Class II, Division 1 InfrequentImmediately shut down and cleanequipment
{add new Table}
Table A.6.7 b
{see upload table}
Additional Proposed Changes
File Name Description Approved
NFPA_499_Table_A6.7_for_zones_submitt.docx Table to support Zones under A6.7 b
Statement of Problem and Substantiation for Public Comment
Table added to support Zones, applying existing 499 Class II- Division design/critieria
Related Public Comments for This Document
Related Comment Relationship
Public Comment No. 1-NFPA 499-2015 [Section No. 1.2] Zone material
Public Comment No. 9-NFPA 499-2015 [Section No. 6.7] Zone material
Public Comment No. 10-NFPA 499-2015 [Section No. A.6.3.2] Zone material
Related Item
Public Input No. 5-NFPA 499-2013 [Chapter 4]
Submitter Information Verification
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Submitter Full Name: David Wechsler
Organization: [ Not Specified ]
Street Address:
City:
State:
Zip:
Submittal Date: Mon Mar 16 11:09:45 EDT 2015
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Table A.6.7a Recommended Frequency of Housekeeping (Class- Divisions)
Housekeeping. Housekeeping frequency (see Table A.6.7a and A.6.7 b) and effectiveness are
significant factors in the presence and control of dust accumulations.
A.6.7 Table A.6.7 a and A.6.7 b lists the recommended frequency of housekeeping
for combustible dusts.
Table A.6.7 criteria should be applied as follows: Given the condition in (1), which should then
be correctly paired with the defined hazardous area classification shown in (2), this would yield a
suggested release frequency and housekeeping activity as addressed in (3) and (4).
Table A.6.7b Recommended Frequency of Housekeeping (Zones)
Depth of Dust Accumulation
on Equipment
(1)
Area Classification
(2)
Release Frequency
(3)
Housekeeping Activity
(4)
Negligible, up to <1 mm (1⁄32 in.)
Unclassified
Infrequent Clean as appropriate
Up to 3 mm (1⁄8 in.) Zone 22 Infrequent Clean as necessary to
maintain less than 3 mm (1/8 in.)
Up to 3 mm (1⁄8 in.) or
occasional cloud
formation
Zone 21 or Zone 22 Occasional Clean at frequency
appropriate to
minimize
additional dust
accumulations or
formation of a
cloud
3 mm (1⁄8 in.) to layer test
value, or presence of dust
cloud
Zone 20 or Zone 21 Continuous/
frequently
Clean at frequency
appropriate to
minimize
additional dust
accumulations
Exceeds layer test value, or
presence of extensive dust
cloud
Zone 20 Infrequent Immediately shut
down and clean
equipment