26 BULLETIN 1373, U. S. DEPARTMENT OF AGRICULTURE 
COMPRESSED AIR 
Compressed air is necessary for cleaning certain equipment around 
an elevator, especially motors, from which it is difficult to remove 
the dust in any other way. A few operators have adapted the 
compressed-air system for general cleaning. A long pipe, with an 
elbow at the upper end, or a compressed-air hose line attached to a 
pole is used to blow the dust from overhead structures which can not 
be easily reached with a broom or brush. This method of cleaning, 
however, creates a dust-explosion hazard and is inefficient. The dust 
blown from overhead forms in clouds, making it necessary constantly 
to guard against the ignition of these clouds as the dust settles to the 
floor. Moreover, the dust must be brushed from the machines or 
the floor, where it settles after being blown from overhead. Overhead 
lodging places for dust should be reduced to a minimum and com- 
pressed ail' should be used only for cleaning the motors or other similar 
surfaces which can not be satisfactorily cleaned in any other way. 
The elimination of overhead ledges reduces cleaning to a minimum. 
Compressed air should be handled carefully when it is used for 
cleaning in plants where the dust-explosion hazard exists. Theclean- 
ing should be done while the plant is not operating and care should 
be taken to see that the windows and doors are open so that the 
building is well ventilated. Special care should be taken to eliminate 
all possible sources of ignition while the cleaning is in progress or while 
the dust remains in suspension. 
The use of steam instead of compressed air, which has been employed 
in some industries with varying degrees of success, may be adapted 
to some parts of grain elevators. 
VACUUM-CLEANING STSTEM 
The adaptation of the vacuum-cleaning system to grain elevators 
for dust removal may still be considered in the experimental stage. 
The general arrangement of such systems, however, is sufficiently 
well standardized to warrant a general description. 
The system must be capable of handling heavier material than the 
ordinary vacuum-cleaning system can handle, because grain and 
foreign material must be rapidly picked up with the dust. More 
rugged fittings are needed in a modern concrete and steel elevator 
to withstand the extra wear and the rougher treatment. Theoret- 
ically, the vacuum-cleaning system is the best for a grain elevator or 
any other plant where the dust-explosion hazard exists, because it 
removes the dust without the formation of dust clouds in the build- 
ing and the dust can be drawn out of cracks and crevices, where it 
would not otherwise be reached. 
In general arrangement a vacuum-cleaning system for a grain 
elevator resembles the ordinary vacuum system used in hotels and 
public buildings. The essential parts are a vacuum producer, a net- 
work of piping leading to all parts of the building, with suitable inlets 
or hose connections, hose, nozzles, and a collector or dust separator, 
installed in the main line to catch the dust before it enters the vacuum 
producer. All of these parts must be well designed and carefully 
installed. 
