Screw Feeders are similar to Screw Conveyors because they both move product from one process to the next, but differ in a very specific way. Screw Feeders have a flood loaded inlet and are specifically designed to meter the product at a fixed or variable rate where a Screw Conveyor is control fed and is designed to maintain a constant rate of discharge based on the control device feeding it. A flood loaded condition is usually identified by the bulk materials being stored initially in a hopper, silo or bin and then transported from these devices by the screw feeder. Normally the feeder screw will have a variable pitch under the inlet and then the balance of the flights will be full pitch.