464 



APPLIED SCIENCE 



FIG. 207. Trap. 



553. Traps. In large communities where houses are 

 quite close together, the sewerage and waste water is dis- 

 posed of by being allowed to flow into an outlet pipe, called 



a drain pipe. The drain pipe flows into 

 a larger one and thence, by the force of 

 gravity, to the sea, river, or to a specially 

 prepared place called a filter bed. To 

 prevent the escape of odors from the drain 

 pipe, each pipe must be equipped with 

 a trap an S-shaped form partially 

 filled with water (Fig. 207). The water 

 in the trap acts as a seal and prevents 

 the gas from escaping into the house. 

 The trap connects with a pipe, called a 



vent pipe, that runs to the roof. The object of a vent pipe is 



to prevent the water from being forced out. 



554. Work of the Plumber. A plumber's work consists 

 of the installation of fixtures for gas, water, sewerage, and 

 drainage purposes; the setting up in buildings and resi- 

 dences of plumbing fixtures and their appurtenances, such 

 as water filters, water meters, hot-water tanks, suction tanks, 

 cold-water tanks, bathtubs, showers, washbasins, sinks, 

 water-closets, and urinals; the installation of water, gas, and 

 waste piping for laundry machines; and of all compressed- 

 air work. The plumber also puts in all toilet and bathroom 

 auxiliaries, such as paper holders, glass shelves, medicine 

 closets, towel racks, and soap and sponge holders. His 

 work also includes the installation of waste-water leaders, 

 soil and vent lines, and the sewerage drains within and beyond 

 the house line to the street main. He plans pipes for hot 

 and cold domestic water supplies, and puts in cooling jackets 



