1. Basics of Seed Conditioning
Dr. Steven Beckham

3. Physical Differences Dimensional Differences A. Length B. Width
C. Thickness
Shape
Density
Surface Texture
Color
Affinity for Liquids
Electrical Conductivity

4. Basic Seed Conditioning
Basic Machines
Air screen machine
Setting the fans
Setting the screens
Bucket elevators
Spiral separator
Precision sizers
Length graders
Aspirators
Gravity tables
Seed treaters

7. Width and Thickness Sizing Techniques (Diagrams Show Cross-Section Views of Cylinders)

10. Basic Seed Conditioning
Air Flow Measurements and Adjustments
Terminal Velocity
Dust conveys at 2,500 fpm; whole soybeans and corn convey at 5,500-6,000 fpm
Fans are rated in CFM (cubic feet of air per minute)
To find velocity – divide CFM / area of pipe or duct
Example – Fan has CFM = 3,000;
If the duct is 10” x 12” = 120 square inches = (120/144) or
0.833 square feet; the velocity = 3,000 / = 3,601 feet per minute
If the same fan had a duct 14” x 14” = 196 square inches = 1.36 square
feet the velocity would be 3,000 / 1.36 = 2,205 feet per minute

11. Basic Seed Conditioning (cont.)
Static Pressure
Any time we decrease the duct size or put a bend in a duct the static pressure
will increase. When static pressure increases, velocity will decrease.
Never increase or decrease the area of the ducts coming out of a cleaner fan
or aspirator fan.
Keep bends to a minimum. If there is a bend make sure the radius of the bend
is a minimum of twice the diameter of the duct.
Keep the total run of ducting to a minimum.

16. Basic Seed Conditioning
Cyclones and Dust Filters
Cyclones work by decreasing the velocity of the air, which falls below the terminal
velocity of the dust or other particles. That causes the dust to settle out. If the cyclone is
too small the velocity will not decrease enough to settle the dust.
Cyclones need to be tuned or balanced. This is done by adjusting the vent cap so that
pressure differential between the vent cap and the bottom discharge is almost equally
balanced. If done correctly a piece of heavy paper will “just fall away” when placed over
the bottom discharge. If the vent cap is open too much dust will plume out the top. If it is
closed too much dust laden air will blast out the bottom.
Dust filters work by actually filtering dust from the air as it passes through. The critical
calculation for sizing dust filters is the – air / cloth ratio. On dirty air from the air screen
machine there should never be more than 10 cfm per square foot of filter cloth. Dust
hoods can get by with up to 30 cfm per square foot of filter cloth.
Filters must be kept clean to work. Pulse jet filters have automatic cleaners built in. Dust
bags need to be shut down periodically and shaken to keep clean.

17. DAMAGE CONTROL Force = Mass * velocity If velocity doubles2
Force = Mass * velocity
If velocity doubles
Force increases 4 times
After 1 second 32 ft. / minute
After 2 seconds 1024 ft. / minute