Fig. 9.—Running-trap. Fig. 10.—Mason’s trap.
Fig. 8 is the bell-trap, so called from its shape. Much used for the drains of paved areas, yards, and cellars; liable to retain dirt, and needs frequent cleaning; not a good trap. Fig. 9 is a running-trap, used in house-drains and other pipes that are nearly horizontal. Fig. 10 represents a mason’s trap. Is built of brick or stone and cement. Used in brick-drains and sewers, in receiving-basins at street corners, etc. Requires frequent cleaning, and should never be used inside a building. Fig. 11 represents the method of trapping a cesspool. The same plan is also used for grease-traps, the outlet-pipe dipping below the surface of the contents so that it is never obstructed by the grease, which floats on top.
Fig. 11.—Trapped cesspool.
A few patent traps are shown as samples:
Fig. 12.—Adee trap. Fig. 13.—Bower trap.
Fig. 12 is the Adee trap, a modification of the D-trap. Fig. 13 is the Bower trap, claimed to be secured against siphonage or back pressure by a rubber ball which floats up against the entering-pipe. Modification of the bottle-trap. Fig. 14 is Bedell’s trap, with a metallic flap or valve, and an opening on the sewer side of the valve, to relieve pressure. Fig. 15 is Stewart’s trap, intelligible from the diagram. Traps are also made of iron or glass, with a mercury seal, which, it is claimed, are proof against siphoning, pressure, or evaporation.
Fig. 14.—Bedell’s trap. Fig. 15.—Stewart’s trap.