UNITED STATES DEPARTMENT OF AGRICULTURE 



BULLETIN No. 379 



Contribution from the Bureau of Chemistry 



CARL L. ALSBERG, Chief, and the 



Office of Public Roads and Rural Engineering 



LOGAN WALLER PAGE, Director 



Washington, D. C. T August 4, 1916 



DUST EXPLOSIONS AND FIRES IN GRAIN SEPA- 

 RATORS IN THE PACIFIC NORTHWEST. 



By David J. Price, Engineer in Charge of Grain Dust Explosion Investigations, 

 Bureau of Chemistry, and PI B. McCormick, Chief, Division of Rural Engi- 

 neering, Office of Public Roads and Rural Engineering. 



Page. 



Introduction 1 



Plan of investigation 2 



Classification of explosions 3 



Results of Held investigation 6 



Static electricity as a cause of ex- 

 plosions 9 



CONTENTS. 



Page. 



Experimental field and laboratory 



work 11 



Nature of dust explosions 17 



Methods developed for preventing ex- 

 plosions or extinguishing fires 19 



Special acknowledgments 22 



INTRODUCTION. 



The large number of fires and explosions in grain separators 

 during the threshing process has awakened unusual interest in the 

 Pacific Northwest during the last two seasons. These fires and ex- 

 plosions were most frequent in the wheat-growing territory in east- 

 ern Washington and northern Idaho, although occasional occurrences 

 were reported in adjoining territory in northeastern Oregon. From 

 reports received from various sources it is apparent that similar 

 explosions and fires have occurred in scattered localities throughout 

 the territory west of the Mississippi River. 



The Department of Agriculture had for some time been conducting 

 studies relative to the causes and prevention of dust explosions in 

 grain mills, elevators, and similar plants. The close relation of 

 thresher explosions to the general study of grain-dust explosions led 

 to the inauguration of a special study of this allied problem in the 

 northwestern field during the 1915 season. As a result of this study 

 166 occurrences were investigated and reported. It is probable that 

 many other explosions and fires took place which were not brought 

 to the attention of the department. 



43454°— Bull. 379—16 1 



