DUST EXPLOSIONS IN GRAIN SEPARATORS. 13 



suggested itself at the beginning of the study. The department, 

 early in 1915, took this matter up with various representative manu- 

 facturers with a view to observing the efficiency of such an installa- 

 tion on threshing machines during operating conditions. The in- 

 A'estigators collected information pertaining to the efficiency of such 

 installations of this nature as were working in the field. 



In one case a machine equipped with a blower system of this kind 

 threshed 27 days in 1914 and 20 days in 1915. During this time only 

 one flash occurred in the dust pipe, but this did not cause a fire. 



The blower system consisted of two 15-inch fans mounted on the 

 frame of the separator below the cylinder and a 20-inch suction fan 

 mounted on the top of the separator. These fans were so arranged 

 that the draft passed up and around the cylinder in the direction of 

 the travel of the grain and straw. The opening to the suction fan 

 was 4 inches in width and extended across the separator. In addi- 

 tion to preventing the formation of an explosive mixture of dust and 

 air, this arrangement had an additional value, according to the 

 owner, in that it cleaned the grain during the threshing to such an 

 extent that he was enabled to get a better price for it. The dust 

 collected by this system was blown through a special 10-inch pipe to 

 the straw stack. 



In another case a single suction fan was located beyond the cylin- 

 der on the opposite side from the main drive belt. In two cases 

 where fire occurred the fan drew the fire out of the machine before 

 any damage was done. The discharge was so located that the fire 

 did not reach the straw pile or the standing grain. 



One of the machines operating in a section of the territorj^ where 

 explosions were very frequent had two fans drawing dust from the 

 ends and above the cylinder. In this machine, however, the arrange- 

 ment was such that there was in the system a large square corner 

 where smut, chaff, and dirt collected, thus defeating the true purpose 

 of the fans. 



SPRINKLER SYSTEMS. 



In addition to developing an efficient grounding system to remove 

 the static electricity generated during the operation of the machines, 

 and in addition to conducting experiments wiih blower systems, the 

 investigators endeavored to determine the relative efficiency of types 

 of sprinkler systems and fire extingiiishers in use. It was found 

 that there were many different types and patterns of sprinkler sys- 

 tems in general use throughout the territory, but they were all 

 included practically in three different classes : 



1. The chemical fire extinguisher. 



2. Water with (a) air pressure, (h) steam pump compression. 



3. Hose from boiler to separator. 



