Air impinging devices encompass a group of seed cleaners that use very high-speed air to strip appendages from the seed kernel (caryopsis or grain). These devices were developed by Aaron Beisel and the late Chet Dewald in Woodward, Oklahoma. Between the two men there are six U.S. Patents. First was the Woodward Laboratory Air-Seed Shucker. The unit recycled seed material through a venturi until the impelling air blast and the acceleration force strips the appendages free from the grain. The dense clean grain drops from the recycling system. An air compressor powers the system, and sample size is about 10 grams. To obtain percentage grain, use the grain mass extracted divided by the total mass of the material sampled and multiply by 100. The shucker is very quick and effective at determining cleaning quality at any phase in the seed cleaning process.
Second was the Woodward Chaffy Seed Conditioning System. Unprocessed seed is metered from a variable-speed, rotating basket onto a high-intensity, oscillating scalper to remove stems, leaves, and light debris. Rotation of the wire basket loosens the entangled unprocessed seed, provides rough cleaning, and controls the flow of material to the scalper and the aerodynamic conditioning system. Following scalping, the aerodynamic conditioning system uses an air blast and resulting acceleration force caused by a venturi to detach a selected amount of the subtending appendages from the grain. The amount of detachment can be controlled by the amount of air blast and acceleration force. A cross-air-flow device removes trash and sends the air-entrained seed to a momentum discriminator that separates seed according to density. The system has effectively processed bluestem species (Bothriochloa spp.) and similar chaffy seed.
Third was the Woodward Chaffy Seed Conditioner 2000. This unit was developed to clean Texas bluegrass (Poa arachnifera Torr.) seed, an extremely fuzzy seed that clings together to form cotton-like rolls or balls. The conditioner 2000 is a single unit with three phases: uniform metering, preconditioning, and quality classification of chaffy seeds. Two variable-speed, horizontal feed augers supply seed to a variable-speed, seed-delivery auger. The rubbing action between the seed masses and the augers separates the seed masses into smaller portions that are then fed into a preconditioning chamber. In the chamber, rotating paddles force seed through a scalping screen. Compressed air aids movement of the seed to the classification unit and assists in expelling debris from the chamber. The classifier sends the air-entrained seed through a venturi for further cleaning. A change in the direction of the air stream carries extraneous material from the system and classifies the seed by propelling the heavier seed further in the momentum discrimination collector.
References / Additional Information
Dewald, C.L.; Beisel, V.A.; Sims, P.L. 1987. Concepts and principles of the Woodward chaffy seed conditioning system. In: Frasier, G.W.; Evans, R.A., eds. Seed and seedbed ecology of rangeland plants. Washington, DC: U.S. Department of Agriculture: 278-282.
Dewald, C.L.; Springer, T.L.; Beisel, V.A. 2003. The Woodward chaffy seed conditioner 2000. Applied Engineering in Agriculture. 19(2): 219-223.