What is defined as a device that regulates, directs, or controls the flow of fluids in piping systems?

A valve is essential in piping systems as it performs the critical function of regulating, directing, or controlling the flow of fluids. Valves can open, close, or partially obstruct passageways for liquids and gases, allowing for precise control over fluid dynamics. They come in various types, such as gate, ball, globe, and check valves, each designed for specific applications. For instance, a gate valve completely opens or closes a flow path, while a globe valve allows for variable flow control.

In contrast, options such as elbows, reducers, and couplings serve different functions in piping systems. An elbow is primarily used to change the direction of the pipe, typically at a 90 or 45-degree angle. A reducer serves to change the diameter of a pipe, facilitating connections between different pipe sizes. A coupling connects two pieces of pipe or allows for a pipe to be joined with a fitting. While these components are all crucial to the overall assembly and operation of a piping system, they do not perform the regulatory function of controlling fluid flow that a valve provides.