Topic summary
U-bend
Extracted from the Wikipedia article Trap (plumbing).
General description
In domestic applications, traps are typically U, S, Q, or J-shaped pipe located below or within a plumbing fixture. An S-shaped trap is also known as an S-bend. It was invented by Alexander Cumming in 1775 but became known as the U-bend following the introduction of the U-shaped trap by Thomas Crapper in 1880. The U-bend could not jam, so, unlike the S-bend, it did not need an overflow. In the United States, traps are commonly referred to as P-traps, as an elbow and horizontal run of pipe on the outlet side of a U-bend creates a (horizontal) P-like shape. It is also referred to as a sink trap because it is installed under most sinks.