In which areas of a drainage system is a quarter bend allowed?

A quarter bend is a type of fitting used to change the direction of drainage pipes. It is designed for use when transferring flow from horizontal to vertical or vice versa.

In drainage systems, a quarter bend allows for a change in direction without causing excessive resistance to flow, which can lead to clogs or slow drainage. The key consideration for their use primarily revolves around the orientation of the pipes being connected.

The option indicating that quarter bends are allowed when changing direction from horizontal to vertical without restrictions aligns with plumbing codes that prioritize efficiency in drainage. When there are no restrictions, it emphasizes the importance of maintaining flow characteristics and minimizing potential obstructions within the pipe system.

In comparison, the other options suggest limitations or specify conditions where quarter bends may not be appropriately used, which does not conform to the broader guidelines provided by plumbing codes regarding horizontal to vertical transitions.