What device can change the direction of flow in a piping system?

The device that can change the direction of flow in a piping system is a fitting known as an elbow. An elbow is specifically designed to redirect the flow of fluid through a piping system by creating a bend. This gives it the distinctive ability to alter the direction of pipeline routes, which is essential in various applications where space constraints or system design require a fluid to flow at an angle instead of straight.

In contrast, a pump is primarily used to move fluids from one place to another and can increase pressure but does not change the flow direction by itself. A valve regulates flow and can stop or allow passage but does not inherently redirect it. Similarly, a reducer is used to change the diameter of a pipe, thereby modifying flow rates rather than changing the flow direction. Thus, the elbow stands out as the correct choice for altering the flow direction in a piping system.