In plumbing design, which type of elbow is typically preferred for drainage lines?

The long sweep elbow is typically preferred for drainage lines due to its design, which allows for a smoother transition in the flow of wastewater. This type of elbow has a larger radius than other elbow types, which minimizes resistance and turbulence as the water flows through the pipe. The smooth trajectory helps prevent clogs and promotes efficient drainage, reducing the likelihood of backflow or blockages.

In contrast, other types of elbows, like the 90-degree elbow or short elbow, create sharper angles in the piping system. These sharper bends can increase the friction experienced by the wastewater, making it more susceptible to slowing down or getting stuck, which can lead to more frequent clogs. While combination elbows may serve specific design needs, they do not generally offer the same advantages for drainage lines as the long sweep elbow. Thus, the preference for long sweep elbows in drainage systems stems from their ability to facilitate better flow and reduce maintenance issues.