What type of pipe fitting would most likely allow for a change in direction of flow?

An elbow fitting is specifically designed to change the direction of flow in a piping system. It allows pipes to be connected at specific angles, typically 90 degrees or 45 degrees, facilitating smooth transitions between sections of pipe. This ability to redirect flow is essential in many plumbing and piping applications where space constraints or the layout of the system requires adjustments in direction.

While unions, caps, and reducers serve important functions in piping, they do not change the direction of flow. A union is used to connect two pipes so they can be easily disconnected, a cap is meant to seal the end of a pipe, and a reducer is designed to connect pipes of different diameters, effectively changing the size of the flow rather than its direction.