DUST CONTROL IX GRAIX ELEVATORS 
11 
to the workhouse wall, to a height of approximately 15 feet, and 
exhausts above the track shed. This surprisingly effective method 
is operated by the pressure created by the surplus air in the boot. 
The duct, however, must offer little friction to the air movement and 
must be so large that the resistance offered to the upward flow does 
not exceed the pressure of the air entering the boot with the grain. 
IX ELEVATOR HEADS AND LEGS 
The most satisfactory and usual method for controlling dust in 
elevator heads and legs is to run a vent pipe from the elevator head 
to the outside of the building (fig. 9). Some operators have applied 
suction to the heads, but most of them have replaced these suction 
connections by vents. Instead of a connection on the elevator head, 
I 
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Fig. 
-Elevator head vent 
some installations have a vent pipeleading from the garner to care 
for the head as well as the garner. In one grain elevator the dust in 
both the garner and the elevator head is controlled by a vent from the 
discharge spout near the elevator head (fig. 10). 
These many methods of controlling the dust conditions in elevator 
heads are the result of the difference in opinion concerning the dust 
and air conditions in an elevator head when grain is being thrown from 
the elevator buckets into the discharge spout leading into the garner. 
The prevailing opinion is that a pressure exists within the head and 
that a vent pipe over the front leg is necessary to relieve this pressure, 
which is supposed to be produced by the fanning action of the buckets. 
