The Prater Vibratory Screener utilizes a vibrating deck that is attached to one or more screening elements. Each of the screens is used to segregate and capture a specific size fraction of the aggregate particle mixture. Screening efficiency is much greater when a vibratory enhancement is added to the sizing process.
The Prater Vibratory Screener uses a revolving eccentric motion generator that provides a circular motion with a vertical plane. High frequency coupled with a short amplitude (stroke) provides maximum screening efficiency.
We discuss rotation, amplitude, and pitch to explain the theory of operation better:
- Rotation. When operating (turning) in the forward direction (with the flow), all material moves downward gravitationally. With-flow rotation is used for capacity rather than high efficiency such as in scalping operations. When operating counter flow, the vibrator operates (turns) in a direction that is opposed to the particulate material’s normal downward flow. With counterflow, larger particles move down the screen faster, and smaller particles stay in contact with the screen longer, which adds to screening efficiency. As a practical point, the easiest way to change from flow to counter flow is to change the motor’s direction.
- Stroke or Amplitude. Prater Vibrating Screens have a unique way of adjusting the amount of vibration imparted to the screened product. The correct stroke setting allows for stratification of the particle mixture during operation, giving individual particles maximum contact with the screen cloth.
- Pitch or Downward Angle. The correct downward angle, an adjustable parameter on Prater units, ensures that the material flows across the entire screen area at a uniform rate.
The proper combination of flow direction, stroke, pitch, and screen cloth size maximizes efficiency and capacity. These parameters are usually optimized ahead of full operational mode by utilizing testing runs.
