DUST CONTROL IN GRAIN ELEVATORS 
17 
18 inches) to permit the escape of the air without creating an exces- 
sive pressure or velocity. On a tightly-covered garner such an instal- 
lation is very effective in controlling dust clouds. A compact arrange- 
ment of vents for both scale and garner, with a canvas curtain in- 
closing the space between the garner and scale hopper (fig. 12), is 
an economical way to control the dust. 
AT BELT LOADERS 
When grain is discharged from a bin hopper or spout onto a moving 
conveyor belt a cloud of dust is produced by the impact of the grain 
upon the belt and by the air currents following the belt. Belts are 
often loaded in a tunnel or basement, places where dust control is 
particularly important. In most elevators the shipping belts run 
through tunnels or areaways under the bins and are loaded by fixed 
spouts. The receiving and transfer belts are usually loaded bj T fixed 
spouts, leading from distributing heads or from transfer spouts. 
Some elevators use movable belt loaders which commonly consist of 
Fig. 13.— Suction hood on belt-loading spout 
a covered sheet-iron hopper with a short spout at the bottom ex- 
tending close to the moving belt. The opening in this spout is con- 
trolled by a gate or valve. In operation, the belt loader is placed 
over the belt in the desired position and grain is fed into the hopper 
from one or more movable spouts, from other belts, or by hand. 
Suction for fixed belt loaders {fig. 13). — A hood at the end of the 
spout and a pipe connecting it to an overhead trunk line have proved 
satisfactory. The hood should be flared to the full width of the 
loading spout and should have the proportions recommended for the 
United States Department of Agriculture hood (fig. 32) . It should 
be installed so that a choke or spill will not force grain or material 
into the suction hood. Suction is applied at the belt loaders in only 
a few elevators, and the installations have not been in use long enougn 
to show all the good and bad features. 
Suction Jor movable belt loaders. — Pipe connections, with a sleeve 
coupling, can be provided at points where the loader is spotted regu- 
larly. The only known method of applying suction at other points 
83278°— 28 3 
