Below are the first 10 and last 10 pages of uncorrected machine-read text (when available) of this chapter, followed by the top 30 algorithmically extracted key phrases from the chapter as a whole.
Intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text on the opening pages of each chapter.
Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.
Do not use for reproduction, copying, pasting, or reading; exclusively for search engines.
OCR for page R1
To
CLAS SI FICATION OF DUSTS
RELATIVE TO ELECTRICAL EQUIPMENT IN CLASS II HAZARDOUS LOCATIONS
Report of the
Committee on Evaluation of Industria 1 Hazard s
NATIONAL MATERIALS ADVISORY BOARD
Commission on Engineering and Technical Systems
National Re search Counc il
National Academy of Sciences
Publication NMAB 353-4
NAT IONAL ACADEMY PRESS
Washi ngto n, D . C .
1982
OCR for page R2
NOTICE: The project that is the subject of this report was approved by the
Governing Board of the National Research Council, whose members are drawn
from the Councils of the National Academy of Sciences, the National Academy
of Engineering, and the Institute of Medicine. The members of the panel
responsible for the report were chosen for their special competences and
with regard for appropriate balance.
_
The report has been reviewed by a group other than the authors according to
procedures approved by a Report Review Committee consisting of members of
the National Academy of Sciences, the National Academy of Engineering, and
the Institute of Medicine.
The National Research Council was established by the National Academy of
Sciences in 1916 to associate the broad community of science and technology
with the Academy's purposes of furthering knowledge and of advising the
federal government. The Council operates in accordance with general
policies determined by the Academy under the authority of its congressional
charter of 1863, which established the Academy as a private, nonprofit,
self-governing membership corporation. The Council has become the principal
operating agency of both the National Academy of Sciences and the National
Academy of Engineering in the conduct of their services to the government,
the public, and the scientific and engineering communities. It is
administered jointly by both Academies and the Institute of Medicine. The
National Academy of Engineering and the Institute of Medicine were
established in 1964 and 1970, respectively, under the charter of the
National Academy of Sciences.
This study by the National Materials Advisory Board was conducted under
Contract No. J-9-F-5-0070 with the Occupational Safety and Health
Administration and continued under Contract No. 210-78-0120 with the
National Institute of Occupational Safety and Health.
This report is for sale by the National Technical Information Service,
Springfield, Virginia 22151.
Printed in the United States of America.
ii
OCR for page R3
ABSTRACT
Thi s document combines material presented in earlier National Materials
Advisory Board reports and revises it to account for changes in the National
Electrical Code that were made in 1981 and that reflect some of the
recommendations of the Committee on Evaluation of Industrial Hazards.
111
l
OCR for page R4
OCR for page R5
PREFACE
The Occupationa 1 Saf ety and Health Administration ~ OSHA ~ of the U. S .
Department of Labor requested that the Committee on Evaluation of Industrial
Hazards of the National Research Council' s (NRC ) National Materials Advisory
Board ~ NMAB )* classify several hundred gases, vapors, and dusts in
accordance with the groupings i n Article 50 0 of the Nationa 1 Electrica 1
Code. ** The committee's expertise is comprised of chemistry; combustion
phenomena; knowledge of codes, - standards, and regulations; electrical
eng ineeri ng; a nd industri al practices .
The committee established two panels to deal with combustible dusts--one
to classify the dusts and one to recommend the test methods needed to
determine dust classification parameters. The conclusions of the Panel on
Dust Test Equipment, amended and approved by the co~runittee, were presented
in 1979 in Te st Equipment for Use in Determining Classifications of
Combustible Dusts ( Report NMAB 3 53-2 ) .
one classy ~ ~ cat' on of dusts by the
Panel on Classif ication of Combustible Dusts, amended and approved by the
committee, was published in 1980 in C1 assif ication of Combustible Dust in
Accordance with the National Electrica 1 Code ~ Report NMAB 353 -3 ~ . This
document combine s the material presented in these earlier reports and revises
it to account f or changes in the NEC that were made in 1981 and that reflect
some of the recommendations of the committee . Thus, this report supersedes
Reports NMAB 3 53-2 and NMAB 3 53-3 .
The work of the committee relative to gases and vapors resulted in two
reports: Matrix of Combustion-Relevant Properties and Classif ications of
Gases, Vapors, and Selected Solids ~ Report NMAB 353-1) was published in 1979
and classif fed certain chemicals based on physical and f lamrnability data.
Classif ication of Ga ses, Liquids, and Vo labile Solids Relative to
Explosion-Proof Electrical Equipment ( Report NMAB 3 53-5 ) was published in
1982 and classifies additional chemical compounds. In addition, the
committee is preparing another report, Rationale for Classification of
Combustible Gases, Vapors, and DuStS with Reference to the National
Electrical Code, ~ Report NMAB 353-6 ) which reviews the classification
procedure s f or gases and vapors and f or dusts and recommends changes to
improve the procedure s.
v
OCR for page R6
The chairman of the committee expresses his sincere thanks to all those
participating in the study as well as to Stanley M. Barkin of the National
Materials Advisory Board who provided staff support. Special thanks are
given to Ernest C. Magison who prepared the first draft of this report and
to Leland J. Hall and Peter J. Schram, respective chairmen of the Panel on
Classification of Combustible Dust and the Panel on Dust Test Equipment.
Homer W. Carhart, Chairman
* The National Materials Advisory Board is a unit of the Commission on
Engineering and Technical Systems of the National Research Council. Its
general purpose is the advancement of materials science and engineering in
the national interest. It fulfills that purpose by providing advice and
assistance to government agencies and private organizations on matters of
J ~
materials science and technology affecting the national interest, by
focusing attention on the materials aspects of problems and opportunities,
and by making appropriate recommendations for the solution of such problems
, . . . . .
J
and tne exploitation of the opportunities.
**The chemicals and materials to be classified originally included those
subject to an earlier N~C study for the U.S. Coast Guard and those listed by
OSHA in the Federal Register on June 27, 1974 (pp. 23541-31. The list
subsequently was expanded (with additional support from the National
Institute for Occupational Safety and Health) to include the gases and
vapors listed in Fire Hazard Properties of Flammable Liquids, Gases,
Volatile Solids,
Manual 325M issued by the National Fire Protection
Association (NFPA) in 1977. The dusts to be classified were those listed in
1976 in the NFPA'S Fire Protection Handbook (pp. 3-107 to 3-114~.
vi
OCR for page R7
COMMITTEE ON EVALUATION OF INDUSTRIAL HAZARDS
Chairman
HOMER W. CARHART, Naval Research Laboratory, Washington, D.C.
Members
FREDERICK R. EIRICH, Polytechnic Institute of New York, New York
LELAND J. HALL, (retired, formerly with The Mill Mutuals, Chicago, Illinois)
ERNEST C. MAGISON, Honeywell Inc., Fort Washington, Pennsylvania
J. ARTHUR NICHOLLS, University of Michigan, Ann Arbor
PETER J. SCHRAM, National Fire Protection Association, Quincy, Massachusetts
ROGER A. STREHLOW, University of Illinois, Urbana-Champaign
Li al son Repre sentative s
PETER BOCHNAK, National Institute for Occupational Safety and Health,
Morgantown, West Virginia
CHIA CHEN, Occupational Safety and Health Administration, Washington, D.C.
ANDREW M. COWAN, Department of Agriculture, Beltsville, Maryland
JOHN A. GERARD, National Institute for Occupational Safety and Health,
Morgantown, West Virginia
RICHARD W. McQUAID, David W. Taylor Naval Ship Research and Development
Center, Annapoli s, Maryland
JOSEPH E. PIPKIN, Occupational Safety and Health Administration,
Washi ngton, D . C.
THOMAS H. SEYMOUR, Occupational Safety and Health Administration
Washington, D.C.
· ~
V11
i
OCR for page R8
Technica 1 Advisors
ERMINE HARTON, (retired, formerly with the U.S. Department of Transportation
Washington, D.C.)
MlJRRAY JACOBSON, Mine Safety and Health Administration,
Arlington, Virginia
N=B Staf f
STANLEY M . BAR=N, Staf f Scientist
-
viii
1
OCR for page R9
Chai -an
PANEL ON CLAS SIFICATION OF COMBUSTIBLE DUSTS
LELAND J. HALL ~ retired, formerly with The Mill Mutuals, Chicago,
Illinoi s
Member s
CHIA CHEN, Occupational Safety and Health Administration,
U.S. Department of Labor, Washington, D.C.
ANDREW M. COWAN, U.S. Department of Agriculture, Beltsville, Maryland
FREDERICK R. EIRICH, Polytechnic Institute of New York, Brooklyn
MURRAY JACOBSON, Mine Safety and Health Administration,
U.S. Department of Labor, Arlington, Virginia
PANEL ON DUST TEST EQUIPMENT
Chai Oman
PETER J. SCHRAM, National Fire Protection Association, Quincy,
Massachusetts
Member s
LELAND J. HALL ~ retired, formerly with The Mill Mutuals, Chicago,
Illinois)
MU PRAY JACOBSON, Mine Saf ety and He alth Administration, Department of
Labor, Arlington, Virginia
ELTON LITCHFIELD ~ deceased, formerly with the Bureau of Mines, U. S.
Department of the Interior, Pittsburgh, Pennsylvania)
ERNEST C. MADISON, Honeywell Inc., Fort Washington, Pennsylvania
ROGER A. STRE:HLOW, University of Illinoi s, Urbana-Champaign
ix
OCR for page R10
OCR for page R11
CONTENTS
Chapte r 1 SUMMARY OF RECOMMENDATIONS
Chapter 2 RATIONALE FOR CLASSIFICATION OF COMBUSTIBLE DUSTS
Page
1
3
3
Introduction
Premises for Classifying Dusts into Groups E, F. and G 4
Conseque nce s of These Premises
Chapter 3 DUST CLASSIFICATION METHODS
4
9
Classifying using the 1981 NEC Resistivity Guidelines 9
Proposed New Classification of Dusts
Te st Apparatu s
Te sting and Re search
Chapte r 4 CLAS SIFICAT ION OF VARIOUS DUSTS
Appendixe s
ma.
A. Ignition and Explosion Ha zard of Dusts
B.
Layer Ignition Temperature
C. E1 ectrical Re sistivity
D. Dusts with Cloud Ignition Temperatures Lower Than
Their Layer Ignition Temperature s
Curricula Vitae of Committee Members
11
14
14
15
23
29
43
48
50
OCR for page R12
