Which type of valve is used to control water flow in plumbing systems?

Ball valves are widely used in plumbing systems to control water flow due to their design and functionality. They consist of a spherical disc, known as the ball, which has a hole through the center. When the valve is turned to allow the hole to align with the pipeline, water flows freely through the valve. Conversely, rotating the valve to a closed position causes the ball to rotate, blocking the flow of water.

The advantages of using ball valves include their ability to provide a tight seal, which prevents leaks. They also offer quick operation since only a quarter of a turn is needed to open or close the valve completely. This makes them ideal for applications where swift action is beneficial, such as emergency shut-offs.

The other types of valves mentioned have specific roles that do not align with the primary purpose of controlling water flow like the ball valve does. Sliding valves are not as common in plumbing applications, while pressure relief valves are designed to release excess pressure, and check valves function to prevent backflow rather than control flow. Thus, the ball valve stands out as the most appropriate choice for water flow control in plumbing systems.