20 
BULLETIN 1373, U. S. DEPARTMENT OF AGRICULTURE 
although it may be better to inclose both the end of the belt and the 
spout opening with a hood. Often the discharge end of the belt is just 
above the floor level, and the hopper or spout into which the grain 
falls is directly below the floor. In such cases a suction hood (fig. 15) 
is satisfactory. A similar hood can be used when the belt discharges 
into a bin, provided the bin opening is small enough to be covered 
by the hood. If open-top bins are used, such a hood is impractical. 
A hood installed above and a little ahead of the discharge point of 
the belt will be valuable in controlling the dust at this point. A 
feeder is generally used where a belt discharges onto another belt. 
When this transfer point is fixed, a suction hood can be attached 
to or installed directly over the hopper. 
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Fig. 15.— Horizontal hood at belt discharge into spout 
Natural drafts can be used to control the dust at belt discharges 
or transfers in only a very few cases. Where a transfer is installed 
in a tunnel, a vent pipe extending from the hood over the transfer 
hopper through the roof of the tunnel to the outside air can be 
used; but it is generally more satisfactory to have the hood at such 
a point connected to a line in which suction is maintained by a fan. 
AT TAILS OF CONVEYOR BELTS 
Some chaff and dust always cling to a conveyor belt handling 
grain after the grain has been discharged. They are deposited at 
the end of the belt where it passes over the end pulley and some 
of the light dust is thrown into suspension, unless steps are taken 
to control it. Some operators consider that the quantity of dust 
discharged at the end of the belts does not warrant the installation of 
dust-control apparatus. Others, however, feel that it is more 
economical to use some mechanical means for removing this material, 
at the same time collecting the light floating dust, than to have an 
employee clean it up at intervals. Operators who have taken this 
view of the matter have developed several hoods for the purpose. 
One type (fig. 16) consists of a trough-shaped hood at the end of 
