PURPOSE OF INVESTIGATION 
The Bureau of Chemistry learned that many of the dust-collecting 
systems installed in grain^ elevators throughout the country could 
not be used or were dismantled because of the objection of the officials 
having jurisdiction over the weighing of the grain. The weighing 
departments stated that grain weights are greatly affected by the 
action of suction used in the collection of the dust. Reports of 
tests conducted by a number of elevator operators, however, indi- 
cated that the weight of the dust removed is almost negligible. 
Some men experienced in handling grain have stated that less dust is 
removed by suction than is lost in handling grain by means of poor 
machinery, with no dust-collecting equipment. 
Confronted with these conflicting statements, the Bureau of 
Chemistry made a preliminary study of the effect of dust collection 
on the weight of grain. The results showed that much depended 
upon the design and installation of the dust-collecting equipment. 
In many cases the equipment seemed to have been installed with no 
knowledge of the fundamentals of good design. In some cases the 
claims of weighing departments that grain had been drawn out by 
improper application of suction to remove the dust at certain points 
between the car which was being unloaded and the scales, were prob- 
ably correct. No information concerning a generally accepted method 
of applying suction or the proper equipment to use could be obtained. 
Every elevator seemed to have its own system of dust control and 
no standards existed. None of the systems were so installed as to 
permit inspection, nor were they so designed that it would be im- 
possible to lift grain by increasing the speed of the fan, with a corre- 
sponding increase of suction. 
The results of these preliminary investigations showed the necessity 
for a detailed study of the problems of controlling the dust conditions 
in grain elevators. 
PROCEDURE 
Office studies, field investigations, and laboratory experiments have 
been conducted. 
Office studies. — The reports and recommendations of various 
regulatory bodies concerning the maintenance of grain weights be- 
tween the different terminal markets were compiled. Engineering 
data on fans, air-velocity measurement, ventilation, and grain-ele- 
vator equipment were obtained. Patents on dust-collecting equip- 
ment and technical articles recommending various dust-control 
appliances were examined. 
Field work. — A survev was made of the dust-control equipment in 
a number of representative terminal elevators along the Great Lakes, 
the Atlantic coast, and the Gulf coast, including plants having the 
greatest variation in type of building and dust-collecting and removal 
equipment and in grain-handling methods. As a rule, the most 
modern and largest elevators at each point were visited. A few of 
the older elevators, where dust-collecting systems had been recently 
installed according to ideas based on practical experience of the oper- 
ating officials, were also visited. 
