DUST EXPLOSIONS IN GEAIN SEPARATORS. 7 



by the investigators as indicating incendiary origin was very small 

 as compared with that advanced by local men. 



PERCENTAGE OF SMUTTED HEADS. 



The percentage of smut present in the wheat crop was determined 

 in each case by taking a sample of a known number of heads and 

 separating it into two parts, one part consisting of those heads 

 which were not affected by smut, the other part of those heads which 

 were affected. The proportion of smutted heads to the whole number 

 of heads in the sample gave the percentage of smutted heads present 

 in the crop. 



Of 112 explosions nearly all occurred during the threshing of 

 grain which contained from 1 to 35 per cent of smutted heads; the 

 average percentage in 108 explosions was 15. There were only three 

 explosions in fields reported to contain no smut. 



Percentage of No. of ex- 



smutted heads. plosions. 



No smut 3 



Less than 1 per cent 1 



1 to 5 per cent 19 



5 to 10 per cent 27 



10 to 15 per cent 1-5 



Percentage of No. of ex- 



smutted heads. plosions. 



15 to 20 per cent '_ 20 



22 to 25 per cent 8 



25 to 30 per cent 7 



30 to 85 per cent 5 



Not known 4 



SIZE OP MACHINE. 



The results of the investigation in relation to the size of machines 

 affected indicate that explosions occurred in all kinds and types of 

 machines, irrespective of size. 



SPEED OP CYLINDER. 



The fact that many explosions occurred while the separator was 

 being operated at the cylinder speed recommended by the manufac- 

 turers indicates that operation of the machine at excessive speed is 

 not essential to produce an explosion. 



POWER USED. 



The kind of power used in operating the machine was of special 

 importance, since one of the early suggestions as to cause was that 

 engine sparks were responsible. It was found that explosions and 

 fires took place in gasoline-driven as well as in steam-driven outfits, 

 and that the cause of ignition was within the machine itself and not 

 external. In 113 machines investigated the power used was as 

 follows : 



Gasoline IS [ Electric motor 1 



Steam 93 [ Horses 1 



As the largest number of machines in the territory were operated 

 by steam power the figures just given do not indicate that steam- 

 driven outfits are more subject to explosions than are other types. 

 They do, however, discount the theory that explosions occurred only 

 in machines operated by steam power. 



