DUST EXPLOSIONS IN GRAIN SEPARATORS. 9 
eral hundred acres of grain were destroyed. The grain loss in the 
fires investigated reached about $50,000. 
MACHINES WITH FIRE-FIGHTING EQUIPMENT. 
A large number of the machines in which fires occurred were 
provided with some fire-fighting equipment, as is shown in the fol- 
lowing summary : 
No. cases. Percent. No. cases. Per cent. 
No fire-fighting equip- Chemical extinguish- 
Ment 2S xe es 28 24.8 CYS: a0ee eau s athe 29 25.6 
Water, steam, etc_____ 43 Son bel Waiter  tankse. 3 saa as, Lie aber) 
From this summary it ‘will be seen that less than 25 per cent of the 
machines were not equipped with fire-fighting apparatus. Since 
the percentage of machines that suffered a total loss (27.4 per cent) 
is in about the same proportion, it is reasonable to conclude that the 
fire-fighting equipment was effective, especially so since in the ma- 
jority of cases where the machines were totally destroyed no pre- 
ventive means had been installed to check the progress of the fire and 
explosion. 
STATIC ELECTRICITY AS A CAUSE OF EXPLOSIONS. 
THRESHING-MACHINE EXPLOSIONS. 
Tt was evident from the beginning of the investigation that a 
large quantity of static electricity was generated during the opera- 
tion of the separator. Workmen admitted that on certain days static 
electricity was noticeably present around the machines. 
One case in which the owner thought the presence of static elec- 
tricity was responsible occurred in Latah County, Idaho. This 
machine was new, having been operated but part of a day. It was 
completely destroyed as a result of the explosion. As the outfit was 
located 15 miles from a railroad and 4 miles from the county road 
there was no reason to suspect incendiarism. The crew was com- 
posed of neighbors, or men known to be reliable. There was 19 
per cent smut (estimated by counting the smutted heads) in the 
crop. The weather was very hot and dry. After summarizing the 
evidence, the investigator concluded that it was clearly a case of | 
smut explosion by electrostatic ignition. 
A similar case occurred in Whitman County, Wash. The owner 
had experienced two fires, one in the evening and the other the 
following morning, neither of them causing much damage to the 
separator but destroying the surrounding grain in the field and the 
threshed grain in sacks. At the time of the occurrence the machine 
was threshing wheat with 31 per cent smut and was located 21 
miles from the railroad and several miles from the county road. 
43454°—Bull. 379 —16——_2 
