Check valves are primarily used to what?

Check valves are specifically designed to limit the flow of water to one direction. This is a crucial function in various plumbing and fire protection systems, as it helps prevent backflow, which can lead to contamination of potable water supplies or disrupt the proper functioning of the system.

When installed, a check valve opens to allow water to flow in the intended direction and then closes automatically when the flow reverses, preventing any backward movement of water. This one-directional flow is essential, particularly in fire protection systems, to ensure that water is delivered effectively to the fire suppression mechanisms without risking the return flow that could compromise system integrity or safety.

Other options do not align with the primary function of check valves: increasing water flow is not a purpose of check valves, nor do they allow backflow or measure water pressure. Thus, the role of check valves in maintaining unidirectional flow is a fundamental operational principle in many systems requiring fluid control.