Which term is NOT associated with check valves in water distribution systems?

The term that is not associated with check valves in water distribution systems is "pivot." Check valves are designed to allow fluid to flow in one direction and prevent backflow. Commonly associated components of check valves include the disc, spring, and flapper.

The "disc" is often used in disc check valves, which can pivot to allow water flow and close to prevent backflow. The "spring" is an important component in some types of check valves, such as spring-loaded check valves, which help keep the valve closed when there is no flow. The "flapper," commonly seen in flapper-style check valves, swings open to let water pass and then closes when the flow reverses.

In contrast, the term "pivot" does not specifically describe a component or mechanism found in typical check valve designs. While a pivoting action may occur in certain mechanisms, it is not a standard term used to describe the function or components of check valves in water distribution systems. Therefore, "pivot" is the term that does not align with the established terminology for check valves.