10 
BULLETIN 1373, U. S. DEPARTMENT OF AGRICULTURE 
from the boot pit. Hoods connected to large suction pipes have not 
proved entirely satisfactory. In most cases a fixed hood can not be 
used. A hood similar to a window awning is sometimes attached to 
the elevator leg. To be effective, these awning hoods must be close 
to the grating and attached to a large suction pipe. If properly 
designed, there seems to be no reason why they can not control the 
dust at this point. 
One elevator has successfully used a hood over the grating to combat 
the dust conditions at that point. This hood is placed over a section 
of the grating, and canvas or other heavy cloth is used to cover the 
rest. This provides a suction on the grain entering the boot pit at 
any point through the grating, from either spouts or tripper (fig. 8). 
Blast Gate 
Slide 
Door 
K Steel Gratm? oyer Boot P/t- 
Fig. 8. — Hood for application of suction to boot pits 
When grain enters the pit through the grating on the other side of the 
leg, the opening for the tripper discharge is closed and the dust is 
drawn up through the section of the grating covered by the hood. 
Sliding doors are provided on each side of the hood, and a gate valve is 
placed in the suction line, where it connects with the hood to regulate 
the suction applied. 
In one grain elevator natural vents are used where the belt dis- 
charges into the boots. The rectangular vents, more than 12 inches 
wide, extend over the full width of the belt. Such an installation can 
seldom be used, but in this particular elevator it was possible to run 
a vent pipe from a point directly over the belt discharge, vertically 
through the cement track-shed floor overhead. The duct runs close 
