24 
central collecting point. This method not only requires a great deal 
of manual labor, but it is inefficient and creates a dust-explosion 
hazard. 
FLOOR-SWEEP SYSTEM 
The floor-sweep system, the most common mechanical method of 
removing dust deposits and accumulations from a grain elevator, 
consists of air trunk lines which lead from fans, preferably outside the 
elevator, to all sections of the plant. Branch lines run down to the 
floor level to floor-sweep hoods, into which the dust is swept. The 
fans exhaust into dust collectors outside the elevator. Sometimes 
these collectors are mounted on the roof of the dust house, far from 
the plant. In extensive systems the collectors discharge into a separate 
fan system, which conveys the collected material to a central collector 
r-A 
v 
^ 
Floor 
Opening 
b X 8 
^% 
Fig. 21.— Floor sweep 
on the dust house. This conveying system is usually outside the 
plant, for its use within the elevator might result in the propagation 
of a dust explosion from one section of the plant to another. For the 
same reason a small separate fan system is desirable to care for each 
section of the elevator. 
The dust is swept, by either brooms or brushes, to the floor-sweep 
hood, into which air rushes at a high velocity. This air gathers up 
the material as it is swept into the hood opening and carries it through 
the piping system. A floor-sweep system is similar to an air-con- 
veying system of the low-pressure type, with the same principles of 
design. 
In the floor-sweep system (fig. 19) the trunk line has a cross-sec- 
tional area equal to the combined areas of all the branches in a certain 
section of the plant. When the cleaning is completed in one sec- 
tion, the suction in the trunk line leading to this section may be 
