BULLETIN 1373, U. S. DEPARTMENT OE AGRICULTURE 
Face Dray " — — r 
Section of Unloading Pjt 
Fig. 1. — Application of suction system to unloading pits 
deals with the methods of removing static dust, that is, dust which has 
settled and accumulated on the floors, walls, equipment, etc, Ven- 
tilation has been divided into natural ventilation and mechanical 
ventilation. 
DUST COLLECTION 
Dust clouds rise at all points in the grain-handling system where 
grain is thrown, agitated, or brought in contact with air currents. 
If no provisions are made for collecting these dust clouds, dust 
deposits are formed on the floors and equipment. The proper use of 
dust-collecting devices and equipment at dust-producing points, 
therefore, not only eliminates the floating dust but also prevents the 
formation of dust deposits. As the removal of dust deposits requires 
labor, the advantage of using well-designed dust-collecting equipment, 
which automatically removes the dust cloud at its inception, is 
apparent. 
Dust is collected by means of suction produced by a fan. Hoods 
or suction connections are placed over all the points where dust 
clouds are created. All these hoods are served by a piping system 
leading to the eye oi a fan, preferably outside the elevator, which 
exhausts into a cyclone dust collector on the roof of a dust house, 75 
to 200 feet from the elevator. In many cases a grain catcher is 
placed directly ahead of the fan to separate the good grain from the 
dust. 
AT EECEIVIXG PITS 
The dustiest points in an elevator are usually about the discharges 
of the receiving or unloading pits. As a rule the discharges of these 
pits are under the track shed, in small inaccessible tunnels, through 
which the receiving belts run to the workhouse. In many cases no 
natural ventilation exists, nor can it be provided in this are away, 
making dust-collecting equipment necessary to remove the dust 
which escapes from the grain as it flows out of the pits upon th e belts. 
