What type of movement does a basic ball valve require to go from fully open to fully closed?

A basic ball valve operates using a simple mechanism where the ball inside the valve has a hole through its center. In the fully open position, the hole aligns with the flow of fluid, allowing it to pass freely. To close the valve, the ball needs to be rotated 90 degrees, or one quarter turn, which aligns the solid part of the ball with the flow path, effectively blocking it and stopping the flow.

This quarter-turn action is what allows ball valves to provide quick and reliable shutoff capabilities. The design is particularly advantageous in applications requiring tight sealing and straightforward operation, as the position of the ball (either aligned with the flow or perpendicular to it) clearly indicates whether the valve is open or closed. This straightforward rotational movement is part of what makes ball valves widely preferred in various industries for on-off control of liquid and gas flow.