C O M M I T T E E P E R S O N N E L

155 DEH-1

Report of Committee on Dust Explosion Hazards

Correlating Committee

W. L. Sands, Chairman, Insurance Services Office, Midwestern Region, 230 W. Monroe Street,

Room 1545, Chicago, Illinois 60606

R. W. Andrews, Jr . , American Society of Mechanical Engineers

J o h n Nagy, Mining Enforcement & Safety Administration, and NFPA Committee on Explosion Protection Systems

*Retired prior to the ballot on Part IV.

G. D. Perkins , Mill Mutual Fire Prevention Bureau

*James B. Walker, Jr . , American Boiler Mfrs. Assn.

G. E. Weldon, Factory Mutual Research Corp.

S e c t i o n a l C o m m i t t e e o n G r a i n a n d F o o d P r o c e s s i n g D u s t s

G. D. Perkins, Chairman, Mill Mutual Fire Prevention Bureau

F. D. Alroth , Underwriters' Laboratories, Inc.

F rank Ber theau , Kellogg Co. L. H. Gre tzer , United Sprinkler Douglas L. Hall, Millers' National Federa-

tion J o h n M. Jensen , CPC International, Inc. F r ank J u n , Quaker Oats Co. Gera ld A. Kars tens , American Feed Manu-

facturers Assn. Louis Klnfl, American Institute of Baking Tony Matt inG. Cargill Inc. J. R. MeCann, National Safety Council G. A. Nafzil!er, The Proctor and Gamble

Company J o h n Nag.y, Mining Enforcement & Safety

Administration, and NFPA Committee on Explosion Protection Systems

Char les e r r , General Foods Parker Peterson, Fire Equipment Manu-

facturers Assn. F rank E. R a d e m a c h e r , Factory Insurance

Association W. L. Sands, Insurance Services Office - -

Midwestern Region Max Spencer, Grain Elevator & Processing

Society Wi l l iam L. Struve, Corn Refiners Assn., Inc. Rober t Vandenber~0 The Terminal Elevator

Grain Merchants Assn. George E. Weldon, Factory Mutual Re-

search Corp. R. F. Well , National Electrical Manufac-

turers Assn. George M. Woods, Jr . , Kemper Insurance

Co.

Al t e rna tes

H. R. Bratvold, Underwriters' Laboratories J. P. Glllls, Fenwal, Inc. (Alternate to' (Alternate to F. D. Alroth) Parker Peterson)

N o r m a n K. Larson, ADM Grain Co. Richard gd l ng t on , Insurance Services (Alternate to 5~ax Spencer)

Office - - Midwestern Region (Alternate to W. L. Sands) Rober t W. Nelson, Factory Insurance Assn.

(Alternate to Frank E. Rademacher) Alfred Finch, National Safety Council Wil l iam T. Tr lnker , Mill Mutual Fire Pre-

(Alternate to J. R. McCann) vention Bureau (Alternate to G. D. Perkins)

156 DEH-2 R E P O R T O F C O M M I T T E E O N D U S T E X P L O S I O N H A Z A R D S

S e c t i o n a l C o m m i t t e e o n M i s c e l l a n e o u s D u s t s

George E. Weldon , Chairman, Factory Mutual Research Corp.

R o b e r t W. Nelson, Secretaril, Factory Insurance Assn.

J o h n A. Beverly, Manufacturing Chemists Association

David W. Bixby, The Sulphur Insti tute A. Bogot , Combustion Engineering, Inc. M u r r a y J a c o b s o n , American Industrial

Hygiene Assn. F r a n k J u n , Quaker Oats Co. J o h n Nagy , Mining Enforcement & Safety

Administration, and NFPA Committee on Explosion Protection Systems

R. H. P e c h s t e i n , American Electric Power Corp.

G. D. Pe rk ins , Mill Mutual Fire Prevention Bureau

P a r k e r Pe t e r son , Fire Equipment Mann- facturers Assn.

J. M. Robinson, American Insurance Assn. W. L. Sands, Insurance Services Office --

Midweetern Region R. F. Schwab, Society of the Plastics In-

dustry Max Spencer, Grain Elevator & Processing

Superintendents R. F. Woll, National Electrical Manufac-

turere Assn.

Alternates

D. P. C o n g d o n , Factory Insurance Assn. J . P . GilIIa, Fenwal, Inc. (Alternate to (Alternate to Robert W. Nelson) Parker Peterson)

R i c h a r d E d i n ~ t o n , Insurance Service~ Office H a r r y Verakis , Mining Enforcement & - - Midwestern Region (Alternate to W . L . Safety Administration (Alternate to John Sands) Nagy)

Thin liet reln'eeente the membership at the time the Comm~2tee was balloted on the text of this edition. Eince that time, chanoes in the memberehip mail have occurred.

The report of the Committee on Dust Explosion Hazards is in four parts.

Par t I proposes withdrawal of NFPA No. 62, Pulverized Sugar and Cocoa.

Par t I has been submitted to letter ballot of the Sectional Committee on Grain and Food Processing Dusts, which consists of 22 voting members of whom 15 voted in favor o/ withdrawal, three voted for reconfirmation, Mr. Jensen asked to be recorded as not voting, and Messrs. Bertheau, Gretzer, and King have not returned ballots.

Par t I has also been submitted to letter ballot of the Correlating Com- mittee, which consists of six voting members, all of whom voted in favor of withdrawal.

Par t I I proposes withdrawal of NEPA No. 657, Confectionery Manufacturing Plants.

Par t I I has been submitted to letter ballot of the Sectional Committee on Grain and Food Processing Dusts, which consists oJ 22 voting members of whom 14 voted in favor of withdrawal, .four voted for reconfirmation, Mr. Jensen asked to be recorded as not voting, and Messrs. Bertheau, Gretzer, and King have not returned ballots.

157 VOTE STATEMENT D E H - 3

Part II has also been submitted to letter ballot of the Correlating Com- mittee, which consists of six voting members, all of whom voted in favor of withdrawal.

Part I I I proposes reconfirmation of NFPA No. 654, Plastics Industry.

Par t I I I has been submitted to letter ballot of the Sectional Committee on Miscellaneous Dusts, which consists of 16 voting members of whom 73 voted in favor of reconfirmation, one voted for withdrawal, and Messrs. Jun and Spencer have not returned ballots.

Part I I I has also been submitted to letter ballot of the Correlating Com- mittee, which consists of six voting members, of whom five voted in favor of reconfirmation, and Mr. Andrews voted for withdrawal.

Part IV proposes a complete revision of NFPA No. 63, Industrial Plants.

Par t IV has been submitted to letter ballot of the Sectional Committe on Miscellaneous Dusts, which consists of 76 voting members of whom 14 have voted affrmatively, Mr. Jacobson voted negatively, and Mr. Pechstein has not returned a ballot.

Part IV has also been submitted to letter ballot of the Correlating Com- mittee, which consists of five voting members, four of whom have voted affrm- atively, and Mr. Andrews voted negatively.

158 INTRODUCTION 63-5

Part IV

Standard for the "

'Prevention. of Dust Explosions in Industr ia l Plants

N F P A No. 63 - - 1 9 7 5

NOTICE An asterisk (*) preceding the number designating a paragraph or

section in the text indicates recommendations in regard to that para- graph or section in Appendix A.

Chapter 1 Introduction 1-1 Purpose.

1-1.1 This standard supplies information for industries that have no specific NFPA standards. I t will enable the plant manager, operator, safety director, fire marshal or others to apprec ia tesome of the more important factors contributing to dust explosion haz- ards in order- to reduce the possibilities of such explosions and minimize the consequences.

1-2 Scope. 1-2.1 This standard is intended to supplement but not replace

other standards listed under the 60 Series of the NFPA standards on dust explosion and the Z12 Series of the ANSI standards on the prevention of dust explosions. Those standards should be fol- lowed for specific applications.

1-2.1.1 Codes covering dust explosion hazards have been formulated by the U.S. Bureau of Mines/Mining Enforcement and Safety Administration in cooperation with other agencies and should be followed where applicable.

1-2.1.2 Experience and laboratory tests show finely-divided particles of virtually all combustible materials and many that are' considered noncombustible but are readily oxidized can produce violent explosions if the particles are suspended in air in the proper concentration and ignited. An examination of a record of explo- sions reported Shows that such dust ignitions have occurred in plants handling grain, flour, feed,~ starch, sugar, powdered milk, insecticides, fertilizers, wood dust, paper dust, cocoa, spices, plastics, synthetic resins, hard rubber dust, cork, coal dust, leather dust, sulfur, metal powders, and many other products.

63-6 DUST EXPLOSIONS IN INDUSTRIAL PLANTS

159

1-2.1.3 For detailed information concerning concentra- tions and other factors entering into the explosibility of dusts and the listing of the dust tested, many of which have been grouped according to their explosibility based both on the maximum pres- sure produced and the rate of pressure rise, see the references in Appendix B.

1-2.1.4 If no published information is available on a dust, tests should be run to determine the explosibility and correlation should be made to other tests.

1-3 Retroactivity.

1-3.1 This standard shall apply to facilities erected subse- quent to the date of this standard and is presented as an advisory guide to owners and operators who may wish to avail themselves of the information herein contained in major replacement or renova- tion of existing facilities.

1-3.1.1 Safety to life, housekeeping, operational procedures, and fire extinguishing requirements shall apply in all cases.

160 GENERAL PRECAUTIONS 63-7

Chapter 2 General Precautions

2-1 Building Construction.

2-1.1 Materials of construction shall be either noncombustible or fire resistive. Exterior walls, roofs, roof houses, intermediate floors, and interior walls shall' be designed in conformity with all applicable local, state, or national building codes.

2-1.1.1 Interior walls specifically erected as fire walls between areas shall be designed for a minimum of three hours fire resistance.

2-1.1.2 All doorways in a fire wall shall be protected by installation of automatic closing Class A fire doors.

2-1.1.3 Interior stairs, manlifts, and elevators between floors shall be enclosed by fire resistive or noncombustible shafts having a fire resistive rating of at least one hour.

2-1.1.4 Stairs, manlifts, and elevator shafts shall be pro- tected by installation of approved automatic closing Class B fire doors on all interior openings.

2-1.1.5 The use of architectural panels shall be limited to those materials having a flame spread classification of 25 or less according to NFPA No. 255-1972, or equivalent.

2-1.1.6 Horizontal surfaces inaccessible for cleaning shall be kept to a minimum to reduce the accumulation of static dust. Where practical, such surfaces shall be built up to an angle of 60 degrees from horizontal.

*2-2 Explosion Relief.

2-2.1 Where a dust explosion hazard exists within a building or structure, such a building or structure shall be designed to relieve the pressures generated in an explosion through relief panels, win- dows, closures, or vents to minimize structural damage to the build- ing and injury to occupants, as recommended in NFPA No. 68- 1974 and NFPA No. 69-1973.

*2-3 Equipment.

2-3.1 Mechanical equipment shall be constructed of metal and be as nearly dust-tight as is practical. Explosion vents on equipment shall be designed in accordance with NFPA No. 68- 1974 or the equipment shall be protected as outlined in NFPA No. 69-1973 to relieve internal explosion pressures.

161 63-8 DUST E X P L O S I O N S IN INDUSTRIAL PLANTS

2-3.1.1 Friction clutches shall be constructed of noncom- bustible material. Torque limiting couplings or fluid drive couplings shall be designed to readily dissipate heat.

2-3.1.2 When drive assemblies must rely on the use of " V " belts or flat belts, such belts shall be of approved static-conduction type and shall be designed with sufficient load service factor to stall the driving forces without slippage.

2-4 Housekeeping. 2-4.1 Good housekeeping is essential and means removal of

old and prevention of new dust accumulations, solid and liquid combustibles , and other materials not necessary for safe and ef- ficient plant operation.

2-4.1.1 Dusts shall be removed either by air suction or other methods which do not produce dust dispersal.

2-4.1.2 Continuous suction shall be installed at open op- erations such as grinding, buffing, dumping of bags, transfer points, and at similar locations. The dust shall be conveyed to safely- located dust collectors. Where possible, the equipment shall be operated at a negative pressure.

162 SOURCES OF IGNITION 63-9

Chapter 3 Sources of Ignition

3-1 General Precautions.

3-1.1 Elimination of all sources of ignition is critical because many combustible dusts (grain and other food products, metallic and wood products, coal and coke, fiber flyings, plastics, etc.) can be ignited by very low energy sparks.

3-1.2 Open flames and smoking shall be prohibited. The use of any welding or flame-cutting equipment for construction or re- pair work shall be prohibited unless the work vicinity is dust-free and otherwise conforms to the recommendations of NFPA No. 51B-1971.

3-1.3 Gun-type tools using powder or cartridges shall not be used where combustible dusts are present.

3-1.4 Use of internal combustion engines shall be avoided unless approved for use in such locations.

*3-2 Electrical Requirements.

3-2.1 All electric wiring and equipment shall conform to the National Electrical Code, NFPA No. 70-1975.

3-3 Static Electricity.

3-3.1 Precautions shall be taken as outlined in NFPA No. 77-1972 to minimize the possible ignition of combustible dusts by static electrical sparks.

*3-4 Spontaneous Heating.

3-5 Blowers and Exhaust Fans.

3-5.1 Blowers and exhaust fans shall comply with NFPA No. 91-1973.

63-10 DUST EXPLOSIONS IN INDUSTRIAL PLANTS

163

Chapter 4 Equipment

4-1 Grinders and Pulverizers.

4-1.1 Location. Where practical, grinding and pulverizing equipment shall be located at or above grade level and segregated from other processes or storage areas.

4-1.2 Stage Size Reduct ion. When more than one stage is util- ized in grinding or pulverizing, material separators shall be used after each stage in size reduction.

4-1.3 Separators. Each grinder or pulverizer shall be equipped with separators to remove t ramp metal and other extraneous ma- terials which could act as an ignition source.

4-2 Conveyor and Material Handling Equipment.

4-2.1 Screw Conveyors. Screw conveyors shall be fully en- closed in noncombustible housings, with free-lifting covers at dis- charge ends. An overload trip shall be installed on the motor driving the. screw.

*4-2.2 Elevator Legs. Elevator leg belts shall be enclosed in separate casings for both up and down legs, except when running through an enclosed beltway between bins. Leg casings, head and boot sections, and connecting spouts shall be dust-tight and con- structed of noncombustible material.

4-2.2.1 Inspection doors of adequate size shall be located in the head section to allow full inspection of head pulley lagging and the pulley side of the leg belt, preferably on the down leg side.

4-2.2.2 Head sections shall be hoppered to the down leg at an angle of not less than 45 ° .

4-2.2.3 Legs shall be driven by individual motors and drives and shall be large enough to handle the full-rated elevating ca- pacity without being subjected to overload, but which shall not be lar.ger than the smallest standard motor rating meeting these re- qmrements.

4-2.2.4 Boot sections shall be at or above the floor level rather than in pits and shall be provided with adequate doors to inspect the boot pulley and leg belt and clean the entire boot. Such doors shall be equipped with dust-tight covers which can be removed without tools.

164 EQUIPMENT -" 63-11

4-2.2.5 Elevator boot sections and spouts feeding them shall be constructed to minimize the possibility of choking. They shall be provided with covered hopper-type inlets to which spills and cleanup can be shoveled back into the leg.

4-2.3 Pneumat ic Conveying. Where materials are to be handled with pneumatic handling, installation of pneumatic equip- ment shall be in accordance with NFPA No. 66-1973.

4-3 Bins and Tanks.

4-3.1 Construction. Bins and tanks, Whether located inside or outside buildings, shall be constructed of noncombustible ma- terial.

4-3.2 Covers. Bins and tanks shall be provided with dust- tight and water-tight covers off the decks.

4-3.3 Openings . There shall be no vent openings between bins or tanks allowing inter-tank passage of air or dust.

4-4 Dust Collectors.

4-4.1 Dust collectors shall be located out of doors or in de- tached rooms unless specifically engineered for indoor installation and the installation is approved by the authority having jurisdiction.

4-4.2 Dust collectors shall not serve several separate processes.

4-4.3 Where bag-type collectors are used they shall be enclosed in a metal housing.

4-5 Dryers.

4-5.1 Requirements for the construction, installation, opera- tion, and maintenance of dryers shall be in accordance with NFPA No. 86A-1973.

63-12 D U S T E X P L O S I O N S I N I N D U S T R I A L P L A N T S ,

165

Chapter 5 Fire Extinguishing

5-1 Portable Fire Protection Equipment.

5-1.1 Portable fire protection equipment suitable for fires in the combustible dusts being handled shall be provided in ac- cordance with the requirements of NFPA No. 10-1974.

5-1.2 Small hose with adjustable.spray nozzles is a suitable alternative to 5-1.1. Solid streams from hose or extinguishers should. be used with great caution where combustible dusts are involved. Dusts may be thrown into suspension by their use, with a consequent explosion. Spray or fog nozzles may be used with much less danger . of disturbing dust deposits and, spray nozzles shall be available for use with all hose provided for fire protection where combustible. dust is present.

"5-1.3 Combustible metal dusts present a special case and where they are present, extinguishing materials suitable for the metal shall be used. These will include agents approved by nationally recognized testing laboratories and nonproprietary materials such as graphite powder, dry sand, iron turnings, sodium chloride, and others.

5-2 Fixed Fire Protection Equipment.

5-2.1 An approved system of automatic sprinklers shall be provided for the protection of all areas containing combustible - materials (other than grain). For grain risks located in areas with inadequate water supplies for a standard system of automatic sprinklers, sprinklers in elevator cupolas and other areas containing combustible material shall be installed and connected to a dry standpipe having outside fire protection department connections.

5-3 Plant Employee Training.

5-3.1 Plant employees shall be instructed as to the hazards inherent in combustible dust handling, storage, or producing oper- ations, and trained in the proper use of extinguishers and small hose for dusts involved.

5-3.2 Plant management shall periodically inform the local fire department of the dangers inherent in using large hose streams and the advantages of spray nozzles.

166 : S A F E T Y TO L I F E 6 3 - 1 3

.. Chap te r 6 Safety to Life

6-1 Plant management shall instruct all employees as to t hepo- tential fire and explosion hazard inherent where combustible dust is present and the particular fire and explosion hazards of dust to which they may be exposed.

6-2 Exit facilities for buildings or rooms where combustible dusts are handled or produced, or liable to be dispersed shall comply with the provisions of NFPA No. 101-1973, Life Safety Code.

63-14 DUST EXPLOSIONS IN INDUSTRIAL PLANTS

167

Appendix A

A-2-2 Venting. An effective means for reducing damage from dust explo- sions is provision for properly designed, proportioned, and maintained explosion- relief vents suitably pl/~ced in the equipment or structure in which an explosion might occur. A vent is an opening designed or developed for the release of. pressure through which the heated explosion gases escape, thus preventing the development of destructive pressure. A vent does not prevent the explosion but, in part, may reduce the rate of pressure development. The most effective vents are free or unrestricted openings. However, in practice, some type of closure that will tear or" blow out under low pressure is required. Typical closures are diaphragms, hinged or blow-out panels, louvers, scored glass panes, hinged windows, or weakly constructed wall or roof surfaces. The placement of the vent should be chosen to minimize injury or damage from the shattering or operation of the vent closure. Where the equipment to be vented is contained within a struc- ture, a duet of sufficient strength should be used to convey flames, hot gases, and burning dusts to a safe location.

The required area of the vent depends on the expected pressure and rate of pressure rise from the dust explosion, the volume and strength of the enclosure, and the type of vent closure.

A-2-3 Inert Gas Systems. Ignition and explosion of dusts can be prevented by inerting or the reducing of the oxygen in the atmosphere below a specific limit. Equipment such as grinders, pulverizers, mixers, driers, conveying sys- terns, dust collectors, sacking machines, and the like can be protected in this manner. In application of dust explosion control by inerting, consideration should be given to protection of personnel, the hazard to be protected, the re- quired reduction in oxygen concentration, inert gas supply, control equipment as well as periodic maintenance, inspection, and testing.

The required safe concentration of oxygen in the dusty atmosphere depends on the reactivity or type of dust, particle size, dust concentration, turbulence, type of diluent gas, and the intensity of the igniting source. A reduction in oxy- gen by carbon dioxide diluent to 11 percent or by nitrogen diluent to 8 percent is recommended to prevent ignition of carbonaceous dusts by spark; where stronger sources of ignition may be present, reduction to 4 percent by carbon dioxide, or 3 percent by nitrogen diluent is recommended. With some types of carbonaceous dusts, slightly higher limiting inerting values might be tolerated.

Explosion Suppression Systems. Explosion suppression is a technique by which burning in a confined space is detected and arrested during incipient stages, preventing development of pressure which could result in an explosion. Equipment such as enclosed reactors, mixers, blenders, pulverizers, mills, driers, ovens, dust collectors, storage vessels, pneumatic transport systems as well as hoods, glove boxes, and other pilot plant equipment are adaptable to explosion control by explosion suppression.

In the design of an explosion suppression system consideration should be given to personnel safety, the deflagrating characteristics of the dust, type of hazard to be protected, detecting methods, suppression technique, and the procedures of installation, operation, and maintenance. Control by explosion suppression involves complex and interrelated technical features. Application is limited by the nature, size, and geometry of the equipment to be protected as well as the physical and chemical properties of the reactants. The design, installation, and maintenance of such systems should be entrusted to trained and competent personnel.

168 kPPENDIX A 63-15

A-3-2 In sections of a plant where combustible dust accumulates or is present in suspension in the air (Class II hazardous locations as defined in Article 500 of NFPA No. 70-1975), electrical installation should be in accordance with Article 502 of the Code, and electrical equipment should be dust-ignition proof. Use of dust collectors, provisions for adequate ventilation, and positive assur- ance of good housekeeping, all described in other chapters of this standard, may qualify sections of a p lant to be classified as Division 2 locations rather than Division 1, thus affording the possibility of using s tandard electrical equipment instead of dust-ignition proof and providing overall increased safety (see Articles 500 and 502 of NFPA No. 70-1975).

A-3--4 In addition to t h e normal precautions on spontaneous ignition, at- tention is called to the hazard of spontaneous heating in many powdered products, particularly after grinding when numerous fresh surfaces are exposed to oxidation. Some products, such as hard rubber,~should be cooled after grind- ing to prevent subsequent heating and ignition.

A-4-2.2 All elevator legs should be provided with automatic mechanical or electro-mechanical devices to shut off all driving power and sound an alarm in the event of belt slow-down or a separation of the leg belt. Tr ibutary con- veyors (all types) which feed the elevator leg should be equipped with an inter- locking device to automatically shut off power simultaneously when power to the elevator leg is interrupted.

A-5-1.3 Practice drills should be held with any of these agents.on the particu- lar combustible metals being handled. Prior knowledge of the cai~abilities - and limitations of agents and associated equipment will aid i n emergency situations.

63-16 DUST EXPLOSIONS IN INDUSTRIAL PLANTS

169

Appendix B

Bibliographical References. For additional explanatory and informative ma- terial, the following publications are recommended reading:

Baumeister, T., and Mark, L., Mechanical Engineers Handbook, 7th edition, New York: McGraw-Hill, 1967, pp. 7 - 3 8 - 7-45

Coffee, R. D., "Dust Explosions: An Approach to Protection Design," Fire Technology, vol. 4, no. 2, May 1968, pp. 81-87

Dorsctt, H. G., Jacobson, M., Nagy, J., and Williams, R. P., "Laboratory Equipment and Test Procedures for Evaluating Explosibility of Dusts," Report of Investigation 5624, Pittsburgh, PA: U.S. Bureau of Mines, 1960

Dorsett, H. G., and Nagy, J., "Dust Explosibility of Chemicals, Drugs, Dyes, and Pesticides," Report of Investigation 7132, Pittsburgh, PA: U.S. Bureau of Mines, 1968

"Dust Explosions in Factories," New Series No. 22, London, England: Ministry of Labor, 1963

Factory Mutual Engineering Corporation, Handbook of Industrial Loss Prevention - - Chapter 66, "Combustible Dusts," 2nd Edition, New York: McGraw-HiU, 1967

Hartman, Irving, "Explosion and Fire Hazards of Combustible Dusts," In- dustrial Hygiene and Toxicology (Patty), rev. 2nd edition, New York: Inter- science Publishers Inc., 1958, pp. 549-578

Hartman, Irving, Cooper, A. R., and Jacobson, M., "Recent Studies on the Explosibility of Cornstarch," Report of Investigation 4725, Pittsburgh, PA: U.S. Bureau of Mines, 1950

Hartman, Irving, Jacobson, M., and Williams, R. P., "Laboratory Explosibility Study of American Coals," Report of Investigation 5052, Pittsburgh, PA: U.S. Bureau of Mines, 1954

Hartman, Irving, Nagy, J., and Jacobson, M., "Explosion Characteristics of Titanium, Zirconium, Thor ium, Uranium and their Hydrides," Report of Investigation 4835, Pittsburgh, PA: U.S. Bureau of Mines, 1951

Jacobson, M., Cooper, A. R., and Nagy, J., "Explosibility of Metal Powders," Report of Investigation 6576, Pittsburgh, PA: U.S Bureau of Mines, 1964

Jacobson, M., Nagy, J., Cooper, A. R., and Ball, F. J., "Explosibility of Agri- cultural Dusts," Report of Investigation 5753, Pittsburgh, PA: U.S. Bureau of Mines, 1961

Jacobson, M., Nagy, J., and Cooper, A. R., "Explosibility of Dusts Used in the Plastics Industry," Report of Investigation 5971, Pittsburgh, PA: U.S. Bureau of Mines, 1962

Nagy, J., Cooper, A. R., and Dorsett, H. G., "Explosibility of Miscellaneous Dusts," Report of Investigation 7208, Pittsburgh, PA : U.S. Bureau of Mines, 1968

Nagy, J., Dorsett, H. G., and Cooper, A. R., "Explosibility of Carbonaceous Dusts," Report of Investigation 6597, Pittsburgh, PA: U.S. Bureau of Mines, 1965

Navy, J.., and Postman, W. M., "Explosibility of Coal Dust in an Atmosphere L:ontmmng a Low Percentage of Methane," Report of Investigation 5815, Pittsburgh, PA: U.S. Bureau of Mines, 1961

170 APPENDIX B 63-17

Nagy, J., Seiler, E. C., Conn, J. W., and Verakis, H. C., "Explosion Develop- ment in Closed Vessels, Report oflnvestigation 7507, Pittsburgh, PA: U.S. Bu- reau of Mines, 1971

'National Fire Protection Association, Fire Protection Handbook, 13th Edition, Section 5, Chapter V, "Fire Hazard Properties of Dusts," National Fire Pro- tection Assn., 1969, pp. 5--49 - - 5-75

Palmer, K~ N., Dust Explosions and Fires, Halstead Press (Division of John Wiley and Co., Inc.), 1973

Raftery, M. M., "Explosibility Tests for Industrial Plants," Fire Research Tech- nical Paper No. 21, Ministry of Technical and Fire Offices Committee, 1968

Rasbash, D. J., and Rogowski, Z. W., "Relief of Explosions in Dust S~tems," Symposium on Chemical .Process Hazards with Special Reference "to Plant Design, London, England: Institution of Chemical Engineers, 1961, pp. 58-69

Schwab, R. F., and Othmer, D. R., "Dust Explosions," Chemical and Process Engineering, April 1964

Schwab, R. F., "Dust Explosions - - Analysis and Control," Hartford, GT: Factory Insurance Assoc.mtion, 1966

Singer, J. M., "Ignition of Coal Dust, Methane-Air Mxitures by Hot Turbulent- Gas Jets," Report of Investigation 6369, Pittsburgh, PA: U.S. Bureau of Mines, 1964

Singer, J. M., Cook, E. B., and Grumer, ~., "Equivalences and Lower Ignition Limits of Coal Dust and Methane Mixtures," Report of Investigation 6931, Pittsburgh, PA: U.S. Bureau of Mines, 1967