The size of floor and yard drains should never be less than 3 in. in diameter, and very often, where there is much service required of them, and where there is any danger of solids of any description entering them, 4 in. is preferable.
Plate 16. Floor Drains & Cellar Drains
The drainage of yards and areas in congested business districts, and in densely populated districts, is a matter of importance to the public health. Under such conditions, all areas, yards, paved courts, and courtyards should be properly drained.
This applies especially to tenement-house districts. The common form of floor and yard drains is of the style to be seen in Fig. A of Plate 40, provided with a removable perforated cover. There are several special forms of drains, such as those shown in Figs. A and B of Plate 16, some of them being provided with a vent connection. Ordinarily, however, drains of this description do not require venting, but may safely be installed without it, as in Fig. C.
Floor and yard drains should always be provided with deep-sealed traps. The deep seal is a special feature of the trap in Fig. A.
An excellent form of trap which will fill this requirement is one made of quarter bends. This trap is generally of the half-S form and may be easily constructed of three quarter bends. The use of a very deep seal on this class of work is not to be feared, as it would be in the case of polluted drainage, for all drainage passing through such drains is composed practically of clear water. In the case of other drainage a very deep seal would allow too large a body of sewage to stand in the trap to putrefy and make the system more impure than there is need of. The drain of Fig. B, with its flushing device, is an excellent one for many purposes, particularly for use in hospitals and on other work where general conditions must be as perfect as possible.
The flushing rim and jet with which the drain is provided allow the entire surface to be thoroughly cleansed, and the cleansing is accomplished without wetting the floor. By means of properly no arranged supply connections, the trap may be flushed with hot or cold water, or with both.
The seal of this trap is of much greater depth than that of the ordinary floor drain. The connection of the water supply with drains of this description is an excellent idea, as a very small drip may be provided which will insure a permanent seal in the trap. Yard drains, for instance, in times of drought, and especially when not provided with deep-seal traps, may become a source of danger from loss of the trap seal. This source of danger, by the way, is an argument in favor of the use of a main trap.
Many plumbing ordinances demand that floor and cellar drains shall be water supplied, and this is certainly a needed precaution.
Floor and yard drains need not be separately trapped when one trap can be made to serve two or more drains, or where such drains are so connected as to be controlled by the trap of a rain leader. In fact, the use of a single trap, especially a rain-leader trap, to control one or more floor or yard drains is an excellent means of protection, as the permanence of the seal of such trap is more positive than the seals of separate traps would be.
In many cities a separate system of sewers is used for the disposal of surface and subsoil waters, no house drainage being allowed to enter it. In this case all floor and yard drains, roof leaders, subsoil drains, etc., should enter the surface water system. When these drains enter the house drainage system, however, no drainage which is not of clear water should be allowed to enter them.
Vitrified earthen pipe may be used for stable drains and for yard drains which are not connected with any house drain. Such drains must always be trapped and connected to the house sewer outside of the connection of the house drain to the house sewer.
When drains are of vitrified earthen pipe they should not be less than 5 in. in diameter.
The practice is sometimes followed of using any convenient cleanout opening as a cellar-floor drain, but it is a poor practice, and should not be followed.
The construction of the cellar drain is shown in Fig. C. This drain is naturally located at the end of the cellar at which the house drain passes out, as the house drain pitches in this direction. The cement bottom should be graded from the several sides of the cellar toward the entrance to the cellar drain.
A catch basin or well is generally formed in the cement, and at the bottom of it the cellar drain trap is located. Even though the system is provided with a main trap, a trap should be used on the cellar drain.
Without it, odors from the house drain would pass through the cellar drain and out into the cellar.
The practice of double trapping on this part of the work will not be followed by the troubles that generally follow double trapping, for the passage of water from the cellar drain is seldom of large volume.
It is a good plan to form in the cement bottom a small gutter, following around the entire cellar wall and close to it, this gutter being led into the catch basin of the cellar drain. By means of the gutter, and the grading of the cellar bottom, any water entering the cellar through the upper part of the foundation, or discharging onto the floor through leaks in the water piping, may find its way into the cellar drain.