(5) Ventilation of the whole system by the fresh-air inlet, vent pipes, and the extension of all vertical pipes.
Definitions.—The House Drain is the horizontal main pipe receiving all waste water and sewage from the vertical pipes, and conducting them outside of the foundation walls, where it joins the house sewer.
The Soil Pipe is the vertical pipe or pipes receiving sewage matter from the water-closets in the house.
The Main Waste Pipe is the pipe receiving waste water from any fixtures except the water-closets.
Branch Soil and Waste Pipes are the short pipes between the fixtures in the house and the main soil and waste pipes.
Traps are bends in pipes, so constructed as to hold a certain volume of water, called the water seal; this water seal serves as a barrier to prevent air and gases from the sewer from entering the house.
Vent Pipes are the special pipes to which the traps or fixtures are connected by short-branch vent pipes, and serve to ventilate the air in the pipes, and prevent siphonage.
The Rain Leader is the pipe receiving rain and storm water from the roof of the house.
Materials Used for Plumbing Pipes.—The materials from which the different pipes used in house plumbing are made differ according to the use of each pipe, its position, size, etc. The following materials are used: cement, vitrified pipe, lead; cast, wrought, and galvanized iron; brass, steel, nickel, sheet metal, etc.
Cement and Vitrified Pipes are used for the manufacture of street and house sewers. In some places vitrified pipe is used for house drains, but in most cities this is strongly objected to; and in New York City no earthenware pipes are permitted within the house. The objection to earthenware pipes is that they are not strong enough for the purpose, break easily, and cannot be made gas-tight.