CHAPTER VII

Plumbing Pipes

The House Drain.—All waste and soil matter in the house is carried from the receptacles into the waste and soil pipes, and from these into the house drain, the main pipe of the house, which carries all waste and soil into the street sewer. The house drain extends from the junction of the soil and waste pipes of the house through the house to outside of the foundations two to five feet, whence it is called "house sewer." The house drain is a very important part of the house-plumbing system, and great care must be taken to make its construction perfect.

Material.—The material of which house drains are manufactured is extra heavy cast iron. Lighter pipes should never be used, and the use of vitrified pipes for this purpose should not be allowed.

Size.—The size of the house drain must be proportional to the work to be performed. Too large a pipe will not be self-cleansing, and the bottom of it will fill with sediment and slime. Were it not for the need of carrying off large volumes of storm water, the house drain could be a great deal smaller than it usually is. A three-inch pipe is sufficient for a small house, though a four-inch pipe is made obligatory in most cities. In New York City no house drains are allowed of smaller diameter than six inches.

Fig. 22.

SYSTEM OF HOUSE DRAINAGE, SHOWING THE PLUMBING OF A HOUSE. (H. Bramley.)

Fall.—The fall or inclination of the house drain depends on its size. Every house drain must be laid so that it should have a certain inclination toward the house sewer, so as to increase the velocity of flow in it and make it self-flushing and self-cleansing. The rate of fall should be as follows:

For 4-inch pipe1 in 40 feet
" 5 " "1 " 50 "
" 6 " "1 " 60 "

Position.—The house drain lies in a horizontal position in the cellar, and should, if possible, be exposed to view. It should be hung on the cellar wall or ceiling, unless this is impracticable, as when fixtures in the cellar discharge into it; in this case, it must be laid in a trench cut in a uniform grade, walled upon the sides with bricks laid in cement, and provided with movable covers and with a hydraulic-cement base four inches thick, on which the pipe is to rest. The house drain must be laid in straight lines, if possible; all changes in direction must be made with curved pipes, the curves to be of a large radius.

Connections.—The house drain must properly connect with the house sewer at a point about two feet outside of the outer front vault or area wall of the building. An arched or other proper opening in the wall must be provided for the drain to prevent damage by settling.

All joints of the pipe must be gas-tight, lead-calked joints, as stated before. The junction of the vertical soil, waste, and rain-leader pipes must not be made by right-angle joints, but by a curved elbow fitting of a large radius, or by "Y" branches and 45° bends.

When the house drain does not rest on the floor, but is hung on the wall or ceiling of the cellar, the connection of the vertical soil and waste pipes must have suitable supports, the best support being a brick pier laid nine inches in cement and securely fastened to the wall.

Near all bends, traps, and connections of other pipes with the house drain suitable hand-holes should be provided, these hand-holes to be tightly covered by brass screw ferrules, screwed in, and fitted with red lead.

"No steam exhaust, boiler blow-off, or drip pipe shall be connected with the house drain or sewer. Such pipes must first discharge into a proper condensing tank, and from this a proper outlet to the house sewer outside of the building must be provided."

Main Traps.—The disconnection of the house pipes from the street sewer is accomplished by a trap on the house drain near the front wall, inside the house, or just outside the foundation wall but usually inside of the house. The best trap for this purpose is the siphon or running trap. This trap must be constructed with a cleaning hand-hole on the inside or house side of the trap, or on both sides, and the hand-holes are to be covered gas-tight by brass screw ferrules.

Extension of Vertical Pipes.—By the main trap the house-plumbing system is disconnected from the sewer, and by the traps on each fixture from the air in the rooms; still, as the soil, waste, and drain pipes usually contain offensive solids and liquids which contaminate the air in the pipes, it is a good method to ventilate these pipes. This ventilation of the soil, waste, and house drain pipes prevents the bad effects on health from the odors, etc., given off by the slime and excreta adhering in the pipes, and it is accomplished by two means: (1) by extension of the vertical pipes to the fresh air above the roof, and (2) by the fresh-air inlet on the house drain.

By these means a current of air is established through the vertical and horizontal pipes.

Every vertical pipe must be extended above the roof at least two feet above the highest coping of the roof or chimney. The extension must be far from the air shafts, windows, ventilators, and mouths of chimneys, so as to prevent air from the pipes being drawn into them. The extension must be not less than the full size of each pipe, so as to avoid friction from the circulation of air. The use of covers, cowls, return bends, etc., is reprehensible, as they interfere with the free circulation of air. A wire basket may be inserted to prevent foreign substances from falling into pipes.

Fresh-air Inlet.—The fresh-air inlet is a pipe of about four inches in diameter; it enters the house drain on the house side of the main trap, and extends to the external air at or near the curb, or at any convenient place, at least fifteen feet from the nearest window. The fresh-air inlet pipe usually terminates in a receptacle covered by an iron grating, and should be far from the cold-air box of any hot-air furnace. When clean, properly cared for, and extended above the ground, the fresh-air inlet, in conjunction with the open extended vertical pipe, is an efficient means of ventilating the air in the house pipes; unfortunately most fresh-air inlets are constantly obstructed, and do not serve the purpose for which they are made.

The Soil and Waste Pipes.—The soil pipe receives liquid and solid sewage from the water-closets and urinals; the waste pipe receives all waste water from sinks, washbasins, bath tubs, etc.

The material of which the vertical soil and waste pipes are made is cast iron.

The size of main waste pipes is from three to four inches; of main soil pipes, from four to five inches. In tenement houses with five water-closets or more, not less than five inches.

The joints of the waste and soil pipe should be lead calked. The connections of the lead branch pipes or traps with the vertical lines must be by Y joints, and by means of brass ferrules, as explained above.

The location of the vertical pipes must never be within the wall, built in, nor outside the house, but preferably in a special three-foot square shaft adjacent to the fixtures, extending from the cellar to the roof, where the air shaft should be covered by a louvered skylight; that is, with a skylight with slats outwardly inclined, so as to favor ventilation.

The vertical pipes must be accessible, exposed to view in all their lengths, and, when covered with boards, so fitted that the boards may be readily removed.

Vertical pipes must be extended above the roof in full diameter, as previously stated. When less than four inches in diameter, they must be enlarged to four inches at a point not less than one foot below the roof surface by an "increaser," of not less than nine inches long.

All soil and waste pipes must, whenever necessary, be securely fastened with wrought-iron hooks or straps.

Vertical soil and waste pipes must not be trapped at their base, as the trap would not serve any purpose, and would prevent a perfect flow of the contents.

Branch Soil and Waste Pipes.—The fixtures must be near the vertical soil and waste pipes in order that the branch waste and soil pipes should be as short as possible. The trap of the branch soil and waste pipes must not be far from the fixture, not more than two feet from it, otherwise the accumulated foul air and slime in the waste and soil branch will emit bad odors.

The minimum sizes for branch pipes should be as follows:

Kitchen sinks2 inches
Bath tubs11/2 to 2 "
Laundry tubs11/2 to 2 "
Water-closetsnot less than 4 "

Branch soil and waste pipes must have a fall of at least one-quarter inch to one foot.

The branch waste and soil pipes and traps must be exposed, accessible, and provided with screw caps, etc., for inspection and cleaning purposes.

Each fixture should be separately trapped as close to the fixture as possible, as two traps on the same line of branch waste or soil pipes will cause the air between the traps to be closed in, forming a so-called "cushion," that will prevent the ready flow of contents.

"All traps must be well supported and rest true with respect to their water level."

Vent Pipes and Their Branches.—The purpose of vent pipes, we have seen, is to prevent siphoning of traps and to ventilate the air in the traps and pipes. The material of which vent pipes are made is cast iron.

The size of vent pipes depends on the number of traps with which they are connected; it is usually two or three inches. The connection of the branch vent to the trap must be at the crown of the trap, and the connection of the branch vent to the main vent pipe must be above the trap, so as to prevent friction of air. The vent pipes are not perfectly vertical, but with a continuous slope, so as to prevent condensation of air or vapor therein.

The vent pipes should be extended above the roof, several feet above the coping, etc.; and the extension above the roof should not be of less than four inches diameter, so as to avoid obstruction by frost. No return bends or cowls should be tolerated on top of the vent pipes. Sometimes the vent, instead of running above the roof, is connected with the soil pipe several feet above all fixtures.

Fig. 23.

LEADER PIPE.

Rain Leaders.—The rain leader serves to collect the rain water from the roof and eaves gutter. It usually discharges its contents into the house drain, although some leaders are led to the street gutter, while others are connected with school sinks in the yard. The latter practice is objectionable, as it may lead the foul air from the school sink into the rooms, the windows of which are near the rain leader; besides, the stirring up of the contents of the school sink produces bad odors. When the rain leader is placed within the house, it must be made of cast iron with lead-calked joints; when outside, as is the rule, it may be of sheet metal or galvanized-iron pipe with soldered joints. When the rain leader is run near windows, the rules and practice are that it should be trapped at its base, the trap to be a deep one to prevent evaporation, and it should be placed several feet below the ground, so as to prevent freezing.