Plumbing fixture
A plumbing fixture is a device which is part of a system to deliver and drain away water, but which is also configured to enable a particular use.
The most common plumbing fixtures are (listed by American plumbing term):
- water closets (aka toilets in America, loos in England)
- urinals
- lavatories (aka bathroom sinks)
- kitchen sinks
- utility sinks
- bathtubs
- showers
- bidets
Each of these plumbing fixtures has one or more water inlets and a drain. In some cases, the drain has a device that can be manipulated block the drain to fill the basin of the fixture. Each fixture also has a flood rim, or level at which water will begin to overflow. Most fixtures also have an overflow, which is a conduit for water to drain away, when the regular drain is plugged, before the water actually overflows at the flood rim level. However, water closets and showers (that are not in bathtubs) usually lack this feature because their drains normally cannot be stopped.
Each fixture usually has a characteristic means of connection. Normal plumbing practice is to install a valve on each water supply line before the fixture, and this is most commonly termed a stop. The water supply to some fixtures is cold water only (such as water closets and urinals). Most fixtures also have a hot water supply. In some occasional cases, a sink may have both a potable and a non-potable water supply.
Lavatories and water closets normally connect to the water supply by means of a supply, which is a tube, usually of nominal 3/8" diameter, which connects the water supply to the fixture. For water closets, this tube usually ends in a flat neoprene washer that tightens against the connection, while for lavatories, the supply usually ends in a conical neoprene washer. Kitchen sinks, tubs and showers usually have supply tubes built onto their valves which then solder directly onto the water supply pipes.
All fixtures have traps in their drains. Traps are sumps, or pipes which curve back down then back up again so that they retain water and create an air seal between the ambient air space and the inside of the drain system. This prevents odors from fouling interior air and also prevents explosive sewer gas buildup. Each fixture drain must be vented so that negative air pressure in the drain cannot suck the trap dry, and so that positive air pressure in the drain cannot force gases past the water seal.
The actual initial drain part in a lavatory or sink is termed a strainer. If there is a removable strainer device that fits into the fixed strainer, it is termed a strainer basket. The initial pipe that leads from the strainer to the trap is termed the tailpiece.
Water closets have the trap built into the fixture itself. The closet is then supposed to seal to the flange of the drain pipe by means of a wax ring. These are traditionally made out of beeswax. However, their proper sealing depends on proper seating of the water closet, on a firm and secure base (floor), and on proper installation of the closet bolts which secure the closet to the flange, which is in turn supposed to be securely fastened to the floor.