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Where possible, the number of bar screens in operation is controlled to maintain the velocity through each screen. This is typically accomplished by calculating velocity based on total flow and the channel level. The gates of the appropriate bar screens are opened or closed as needed to accomplish this task. This is often done in a lead–lag series so that it is known which screen to start or stop next.

Before opening the channel of a bar screen, the rake of that bar screen is typically operated for one cycle to ensure that the screen is clear. Similarly, the rake is operated after closing the channel to ensure that it will be ready for the next cycle.