This seal prevents gases from the sewage system entering the building.įrom the trap sewage travels through drainage pipes in branch lines to a vertical stack. The trap catches and holds a small quantity of water to provide a seal. Some traps are part of the design of the fixture and are not visible, as in a toilet or double sink. A trap is the u-shaped pipe found below a sink. The first component connected to a fixture is a trap. Plumbing drawings are usually numbered beginning with “P,” as in P-1, P-2, etc. A plumbing floor plan will typically show the location and type of plumbing fixtures, as well as the route pipes will be run (overhead or through walls) for potable water, drainage, waste, and vents. Drainage works by gravity: Drain pipes must slope downward. Water is supplied under pressure through pipes to plumbing fixtures. Plumbing systems involve two major components, water supply and drainage.
Plumbing drawings provide all pertinent information on the design of the plumbing system for a project, including line sizes and location, fixture location, isolation valves, storage-tank capacities, hot- water-heater capacities and locations, and drain locations and routing.
