In what type of application are 90° elbows typically used?

90° elbows are primarily utilized in applications requiring a change in the direction of piping in vertical orientations. This type of fitting is essential when a pipe run needs to ascend or descend without interrupting the flow of the material being transported. The design of the 90° elbow allows for a smooth transition, which helps prevent flow obstruction and minimizes turbulence.

In a vertical application, using a 90° elbow enables a rapid shift from horizontal to vertical placement or vice versa, facilitating efficient routing of piping systems in various installations such as plumbing, HVAC, and industrial processes. The fitting's geometry is specifically tailored to maintain the integrity of the flow path during these changes in direction, making it a fundamental component in achieving proper system functionality and efficiency.

The other options refer to applications where the nature or angle of the pipe connection does not involve a straightforward vertical shift, highlighting the specific role that 90° elbows play in vertical changes in piping.