8 
BULLETIN 1373, U. S. DEPARTMENT OF AGRICULTURE 
leg, on the side of the boot, on the top of the boot, or on the spout 
feeding the leg. Not all of these methods, however, are satisfactory. 
When a belt discharges directly into a boot, the common practice 
is to place a dust-collecting hood in a vertical position at the boot 
opening (fig. 3). In some cases the hood is placed in a horizontal 
position (fig. 4). Both of these installations have advantages and 
disadvantages. For equally effective results the vertical hood must 
be larger and handle more air than the horizontal hood. The hori- 
zontal hood, however, is more likely to draw in grain that is thrown 
into the mouth of the hood. In some cases an elbow at the opening 
of the vertical hood (fig. 5) gives the good points of both hoods. A 
vertical hood, having the proportions of the United States Depart- 
ment of Agriculture hood, with the elbow having a radius one and 
one-half times the width of the hood, is satisfactory. 
In the case of a spout feeding into the boot it is sometimes possible 
to place the hood above the point where the spout enters the boot. 
If the grain is far enough from the induced air currents, it may be 
possible to make a direct connection at this point (fig. 6). The 
application of suction to the front leg or the back leg or on the side of 
the boot is not satisfactory. When connections are made in the 
front and back leg, the dust conditions in the boot are not very well 
controlled. The installation of hoods in the front leg and the side of 
U.S.D.A 
Hood 
Fig. .5. — Hood equipped with elbow intake for elevator boot 
