UNITED STATES DEPARTMENT OF AGRICULTURE 
BULLETIN No. 681 
Also Bulletin 26 of The Engineering Experiment Station, 
The Pennsylvania State College. 
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Contribution from the Bureau of Chemistry, CARL L. 
ALSBERG, Chief, 
And the Engineering Experiment Station, The Pennsyl- 
vania State College, R. L. SACKETT, Dean. 
JfW^Swi* 
Washington, D. C. 
May 18, 1918 
GRAIN-DUST EXPLOSIONS: 
INVESTIGATION IN THE EXPERIMENTAL ATTRITION MILL 
AT THE PENNSYLVANIA STATE COLLEGE. * 
By B. W. Dedrick, Instructor in Milling Engineering, and R. B. Fehr, Assistant 
Professor of Mechanical Engineering, The Pennsylvania State College, in collaboration 
with David J. Price, Engineer in Charge, Grain-Bust Explosion Investigations, 
Bureau of Chemistry, Department of Agriculture. 
CONTENTS. 
Object and scope of the investigation 
Principles underlying grain-dust explosions. . 
Apparatus used in investigation 
Materials usod in investigation 
Experimental work 
Experiments from April 6, 1916, to October 
3, 1917 
Page. 
1 
4 
6 
10 
10 
12 
Page. 
Discussion of results and conclusions 39 
Summary of conclusions 48 
Appendix : 
Recommendations for future investiga- 
tions 49 
Resume of some past explosions 49 
Bibliography 52 
OBJECT AND SCOPE OF THE INVESTIGATION. 
The great loss of life and property resulting from explosions in coal 
mines, flour and feed mills, grain elevators, thrashing separators, etc., 
emphasizes the fact that carbonaceous dusts are very inflammable 
and that careful laboratory and field investigations should be con- 
ducted in order to devise means for combating this great danger. 
Although Faraday in 1844 suggested that coal dust suspended in air 
would propagate an explosion, it has been recognized only within the 
past 30 years that coal dust is explosive without the presence of 
a combustible gas. And not only coal dust, but many other carbo- 
naceous dusts are now known to be very inflammable and capable 
of propagating flames. Some idea of the large amount of attention 
that has been given to the explosibility of dusts can be gained by 
referring to the bibliography at the eud of this bulletin (p. 52) and 
to that printed in Bureau of Mines Bulletin 20, which deals particu- 
larly with coal-dust explosions. 
1 The erection of the mill and the conduct of the experiments were under the charge of B. W. Dedrick 
and R. B. Fehr, of the Department of Mechanical Engineering, assisted by P. X. Rice, R. E. Campbell, 
and E. F. Grundhoeffer, instructors in experimental engineering, and C. L. Charles, student assistant. 
50220°— 18— Bull. 681 1 1 
