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1 UNCLASSIFIEDAD NUMBERADB270510 NEW LIMITATION CHANGETOA pproved for public release, distributionunlimitedFROMD istribution authorized to Gov' only; Proprietary Information ;SEP 2002. Other requests shall be referredto AMPTIAC IIT Research Institute, 201 Mill Street, Rome , New York , per DTIC Form 55, 18 Jun 2009 THIS PAGE IS UNCLASSIFIEDRI bureau of mines 6 1report of investi ons6516,EXPLOSIBILITY OF METAL POWDERSBy Murray Jacobson, Austin R. Cooper, and John Nagy20010917 067 Reproduced From NT or. Best Available CopyUNITED STATES DEPARTMENT OF THE INTERIORBUREAU OF MINES \v,.. >. C. OF METAL POWDERSBy Murray Jacobson, Austin R.

2 Cooper, and John NagySreport of investigations 6516~t4T 0~UNITED STATES DEPARTMENT OF THE INTERIORS tewart L. Udall, SecretaryBUREAU OF MINESM arling J. Ankeny, DirectorThis publication has been cataloged as follows:Jacobson, MurrayExplosibility of metal powders, by Murray Jacobson, AustinR. Cooper, and John Nagy. [Washington] U. S. Dept. of theInterior, bureau of Mines [1964]25 p. illus., tables. (U. S. bureau of Mines. Report of investi-gations 6516)1. Dust explosion. I. Title. II. Title: Metal powders, Explosi-bility of (Series) no. 6516 S. Dept. of the Int. LibraryCONTENTSPageAbstract .. 1 Introduction .. 1 Sample description and reporting procedures.

3 2 Discussion of explosibility data .. 3 Particle diameter .. 7 Ignition temperature of dust layers .. 9 Pyrophoricity .. 9 Prevention of ignition and explosion .. 10 Appendix .. Pressure and rate of pressure rise developed by explosions offlaked and atomized aluminums .. 62. Effect of average particle diameter of atomized aluminum onexplosibility index .. 73. Effect of average particle diameter of atomized aluminum onexplosion parameters .. 8 TABLES1. Ignition and explosibility of metal powders .. 42. Ignition and explosion parameters of aluminum alloys .. 73. Effect of coarse combustible particles on pressure and rates ofpressure rise developed by atomized aluminum (33) dust explosions 94.

4 Ignition and reaction temperatures of metal-powder layers in anair, carbon dioxide, or nitrogen atmosphere .. 10A-1. Description, explosibility index, and particle size of dusts .. 11A-2. Ignition sensitivity, relative flammability, and limiting oxygenconcentration of atmosphere for dusts .. 15A-3. Explosion severity, pressures, and rates of pressure rise of dustexplosions .. 4 .. 20 EXPLOSIBILITY OF METAL POWDERSbyMurray Jacobson,1 Austin R. Cooper,2 and John Nagy3 ABSTRACT IData obtained in the bureau 's study of dust explosions of 313 elementalmetals, alloys, catalysts, and ores comprising 54 types of material are sum-marized. Information is given on ignition temppature, spark energy for igni-tion, minimum explosion concentration, explosion pressure, rate of pressurerise, and in some instances, the admixed inert dust and oxygen concentrationin an atmosphere required to prevent ignition of dust dispersions.

5 The effectsof particle diameter on explosibility and pyrophoricity are also discusseINTRODUCTIONE xplosion hazards of numerous dusts have been evaluated during the past25 years by the bureau of Mines. These data are being grouped according totype of material and are being made available to industry. Publications onagricultural4 and plastics5 dusts have been released. The present reportlists laboratory data on 313 metal, alloy, catalyst, and ore samples comprising54 separate types of material; it supersedes earlier reports in which limited'Supervisory research physicist, Health and Safety Research and Testing Center , bureau of Mines, Pittsburgh, science technician, Dust Explosions Research Section, Branch of DustExplosions, Health and Safety Research and Testing Center , bureau of Mines,Pittsburgh, , Branch of Dust Explosions, Health and Safety Research and TestingCenter, bureau of Mines, Pittsburgh, , Murray, John Nagy Austin R.

6 Cooper, and Frank J. Ball. Explosibil-ity of Agricultural Dusts. BuMines Rept. of Inv. 5753, 1960, 23 , Murray, John Nagy, and Austin R. Cooper. Explosibility of DustsUsed in the Plastics Industry. BuMines Rept. of Inv. 5971, 1962, 30 on manuscript completed March on metals were The equipment and procedures used in dustexplosibility evaluation have been described DESCRIPTION AND REPORTING PROCEDURESA description of the samples tested is contained in the appendix. Theparticle size of a dust is shown as the percentage smaller than a given diam-eter (in microns), 8and when available the average particle diameter deter-mined by the Fisher subsieve analyzer is empirical explosibility index is used in rating the hazard of a index is not derived from theoretical considerations, but is consistentwith observations in research and from experience.

7 The index of explosibilityis related to ignition sensitivity and explosion severity. Ignition sensitiv-ity is assumed to be a function of ignition temperature, minimum ignitionenergy, and minimum explosive concentration. Explosion severity is assumedto be a function of maximum explosion pressure and rate of pressure rise. Theignition sensitivity, explosion severity, and explosibility index are definedas unity for a dust having ignition and explosion characteristics similar tothat of Pittsburgh seam coal and are calculated as follows:Ignition .(Ign. temp. x min. ign. energy x min. conc.) Pgh. coal dustsensitivity (Ign. temp. x min. ign.)

8 Energy x min. conc.) sample dustExplosion .(Max. explosion press. x max. rate of press. rise) sample dustseverity (Max. explosion press. x max. rate of press. rise) Pgh. coal dustIndex of explosibility = Ignition sensitivity x explosion , Irving. The Explosion Hazard of Metal Powders and PreventiveMeasures. Metals Handbook. Am. Soc. Metals, 1948, pp. , Irving, and Harold P. Greenwald. The Explosibility of Metal PowderDust Clouds. Min. and Met., v. 26, July 1945, pp. , Irving, John Nagy, and Hylton R. Brown. Inflammability and Explo-sibility of Metal Powders. BuMines Rept. of Inv. 3722, 1943, 44 , Irving, John Nagy, and Murray Jacobson.

9 Explosive Characteristicsof Titanium, Zirconium, Thorium, Uranium, and Their Hydrides. BuMinesRept. of Inv. 4835, 1951, 16 , Henry G., Jr., Murray Jacobson, John Nagy, and Roger P. Equipment and Test Procedures for Evaluating Explosibility ofDusts. BuMines Rept. of Inv. 5624, 1960, 21 No. Size, microns Sieve No. Size, microns20 .. 840 270 .. 53100 ..149 325 .. 105 400 .. 37200 .. 749 Reference to specific brands is made to facilitate understanding and doesnot imply endorsement of such items by the bureau of relative hazard of a dust is also given by adjective ratings of none,fire, weak, moderate, strong, and severe. These ratings are correlated withthe index of explosibility as follows:Relative explosion hazard index Index 0 Weak.

10 <.1 Moderate .. >10 Materials that are not ignited by electric spark or in the furnace areconsidered to present no explosion hazard. A notation of << designatesmaterials that ignite in the furnace but not by the spark or flame calculating explosion severity, the explosion pressure and maximumrate of pressure rise developed at a dust concentration of oz/cu ft areused except for the aluminum-iron alloy, cadmium, and gold bronze; the dustconcentrations of these materials were , , and oz/cu ft, respec-tively. Two techniques were used in obtaining explosion pressure and rateof pressure rise in the studies on metal dusts. Before 1950, dust was dis-persed by an airblast from an 80-cubic-inch reservoir charged to 14-psigpressure (technique A).