siphons(ABelonogov); traps(In plumbing, a trap is a device which has a shape that uses a bending path to capture water to prevent sewer gases from entering buildings. In refinery applications, traps are used to prevent hydrocarbons and other dangerous gases from escaping outside through drains. In domestic applications, traps are typically U, S, 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 Cummings in 1775 but became known as the U-bend following the introduction of the U-shaped trap by Thomas Crapper in 1880. The new U-bend could not jam, so, unlike the S-bend, it did not need an overflow. The most common of these traps in houses is referred to as a P-trap. It is the addition of a 90 degree fitting on the outlet side of a U-bend, thereby creating a P-like shape. It is also referred to as a sink trap because it is installed under most house sinks. WK Alexander Demidov)
