Which type of fitting would be used to change the direction of a pipe?

The correct choice is the elbow fitting, which is specifically designed to change the direction of a pipe. Elbows are available in various angles, commonly 90 and 45 degrees, allowing for sharp bends or less acute changes in the flow of piping systems. This flexibility makes them essential in situations where space constraints or the layout of the piping require redirection.

In contrast, couplings are used to connect two straight sections of pipe without changing the direction, while a wye fitting is intended to split the flow into two directions, maintaining a more gradual angle. A reducer, on the other hand, is designed to change the diameter of the pipe from a larger to a smaller size and does not facilitate directional changes. Each of these fittings serves valuable functions in plumbing and piping systems, but when it comes to altering the path of flow, an elbow fitting is the most appropriate choice.