Pneumatic Dust Control in Grain Elevators Guidelines for Design Operation and Maintenance (1982) / Chapter Skim
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Appendix D: Steady State Velocities
Appendix D: Steady State Velocities
Pages 109-116
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From page 109... ...
Test methods are described and results are given in the following pages. The MAC tests calculated air velocities from velocity pressures obtained with an inclined manometer, while the National Agra tests employed a "hot-wire" direct reading velocity meter.
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From page 110... ...
Method I A 4-foot clear-plastic tube, open at both ends with an inside diameter of 2.75 inches, is mounted vertically in a wood box as an air plenum. A variable speed fan is arranged to discharge air in the box, which is forced up the tube.
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From page 111... ...
2,000 1,400 1,700 1,300 1,400 Method II A 4-foot clear-plastic tube, open at both ends with an inside diameter of 2.75 inches, is mounted vertically in a wood box used as an air plenum. A wire mesh cup is placed over the top of the tube.
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From page 112... ...
Oats (heavy) Departure Velocity of Large, Light Foreign Material 700 650 450 450 450 Nonstable Velocity of Whole Grain 1,250 700 650 650 700 Departure Velocity of Whole Grain 1,900 1,600 1,625 1,250 1,300 Method III - Inlet Velocity A 4-foot clear plastic tube, open at both ends with an inside diameter of 2.75 inches, is placed vertically and 3/8 inch from the floor.
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From page 113... ...
Terminal velocity can be described as that laminar air flow which will suspend the material in a vertical air stream. The material will not rise nor fall at its terminal velocity, which is also referred to as float or suspension velocity.
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From page 114... ...
STUDY OF AIR VELOCITIES REQUIRED TO MAINTAIN VARIOUS GRAINS IN SUSPENSION.* ABSTRACT Efforts to develop standards for pneumatic dust control systems in grain elevators have revealed basic data deficiencies.
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From page 115... ...
Transparent Tube Plenum Chamber Variable Speed Fan 12" JL 48' * Courtesy of Duane W
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From page 116... ...
CONCLUSIONS Even though the results are subject to some variations because of differing test weights, kernel shapes, etc., they provide a range of maximums, which are safely above the velocities needed at dust pick-up points for control of dust. It will be noted that oats have the lowest pick-up velocity (900 fpm)
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