The subject of floor drains pertains more especially to large work of a public nature, such as public toilet rooms of hotels, schools, factories, etc., apparatus rooms and hose towers of engine houses, washrooms of stables, etc., and in general seldom appears in residence or other similar work. In general, the remarks on the cellar drain, made in a previous chapter, apply also to floor and yard drains.

Whenever a double system of sewers is provided, one for house drainage and the other for surface water, these drains should be connected to the surface house drain, but in the absence of the double system they may be connected to the house drainage system. Floor drains should be at least 3 inches in diameter and be provided with deep seal traps, with cleanouts of the same size.

An example of floor-drain connections may be seen in Fig. 114. The floor should be graded so that all water falling on it may run into the drain. It is very customary to use the drain having a bell trap as shown in detail in Fig. 114. This trap is a very shallow one, whose seal is easily lost from evaporation. It is preferable to use a plain drain without the bell attachment and use a deep seal cast-iron trap, as shown. All yards, areas, or other similar surface should be provided with a drain similar to that of Fig. 114. Whenever connected to the house drain direct, each should be separately trapped. Two or more drains of this character may often be connected into one main, in which case each separate drain does not require a separate trap, but a trap placed on the main may be used instead to protect the several drains. It is often convenient also to connect floor and yard drains into rain leader pipes, under which conditions the trap on the rain leader offers sufficient protection without the trapping of each drain. In fact, connections of this kind have an advantage over separate trap connections in the fact that when dependence is made on the one trap the several drains may be depended upon to renew and maintain its seal with much more certainty than a single drain could be depended upon to maintain the seal of its own trap. Stable wash racks or other wash racks from which waste, carrying sediment or solid matter, issues, should not be connected to any part of the drainage system unless a catch basin with trap is provided to prevent such matter from passing into the drainage system.

Fig. 114.   Floor Drain.

Fig. 114. - Floor Drain.

All rain leaders should be trapped on plumbing systems which are not provided with a main trap, but on the trapped system the trapping of rain leaders is not necessary, as the main trap affords protection to the roof leaders. In general, the least number of traps possible to afford ample protection is preferable to the use of a greater number, as double trapping is attended with greater danger of stoppage and with a much slower outflow of sewage, owing to air lock between the traps. Whenever rain leaders are run to the roof inside the building they should be constructed of soil pipe, but when run outside they may be of galvanized sheet iron to a point not less than five feet from the ground, at which point they should enter a soil-pipe branch. In Fig. 115 are shown the customary rain-leader connections. When the rain leader is run inside the building, of cast iron, the connection with the roof gutter should be made by means of a brass ferrule, calked into the soil pipe, to which is wiped the lead or copper pipe connecting with the gutter. The opening of the gutter connection should be funnel-shaped and provided with a wire basket as a protection against the entrance of leaves, twigs, etc., into the conductor pipe and drainage system.

Fig. 115.   Rain Leader Connections.

Fig. 115. - Rain Leader Connections.

When two or more rain leaders enter the same branch, and no soil or waste pipe enters between or back of them into the same branch, a single trap on the branch may take the place of a separate trap on each leader, this trap, of course, being placed on the sewer side of the leader entering nearest to the house drain. The size of rain leaders should depend on the amount of roof drainage each one is required to take care of, but should never be less than 3 inches in diameter. As already stated concerning cellar drainage, traps of floor and yard drains, rain leaders, etc., should have as deep a seal as practicable. The depth of seal is limited in the ordinary cast-iron trap, but a trap can be made, such as shown in Fig. 115, which will provide any depth of seal desired. The trap is constructed of quarter bends, and may be made of any additional depth by using a straight piece of pipe on the outlet leg of the trap between the two bends. A seal of great depth would be an unsanitary device if applied to the house-drainage system, as it would provide a lodging place for a large quantity of waste, which would soon putrefy and render the system more impure than there is any necessity for. The water passing through floor and yard drains and roof leaders is clear, however, and depth of seal need, therefore, not be limited. Drainage from fixtures should never be allowed to enter any of these drains.

In connection with the cellar work of the plumbing system, the use of the cellar drainer is a very important feature under certain conditions. It often happens that the street sewer is at such a high level that the house drain, in order to gain sufficient pitch, must be carried above the cellar bottom. In this event, it is clear that the cellar drainage into a catch basin supplied with a trap, such as described in a previous chapter, will not answer the purpose, as it is located so low that it cannot deliver into the house drain by gravity, in the ordinary manner.

The cellar drainer, of which there are several makes, is made use of extensively under these conditions. This device is generally operated by the pressure of water in the house supply system. In Fig. 116 is shown the connections for the cellar drainer and the manner in which its work is performed. Cellar drainers are made to act automatically. When the water accumulates in the catch basin in which the drainer is located it gradually raises a float,

When it has risen to a certain point it opens a valve, which admits the water supply, which discharges the water collected in the catch basin. This water is discharged into a sink installed for the purpose, or, if it so happens, into any similar cellar fixture which may be convenient. This sink should be trapped and vented just as any other house fixture. The action of the cellar drainer depends upon the creation of a partial vacuum by passing water or steam under pressure through a jet, thereby producing a suction which draws the water out of the catch basin or other receptacle into the discharge pipe, the pressure forcing it up to the point of delivery. It will be observed that both surface water and the water used in operating the drainer are discharged. When the float falls it closes the valve and the device is ready for its next operation.

Fig. 116.   Connections for Cellar Drainer.

Fig. 116. - Connections for Cellar Drainer.

Some manufacturers claim that the cellar drainer will lift water through 12 feet, but it would appear that 8 to 10 feet is about the limit. Even so, however, the drainer covers a wide range of work. It is made in various sizes, capable of caring for 50 gallons to 1,200 or more gallons per hour. The minimum pressure required is generally about 15 lbs. The greater the distance through which the water is to be lifted the greater will be the amount of water necessary to operate the drainer. In addition to its use in connection with the drainage of cellars, it is often used in draining cesspools, wheel pits, catch basins, into which refrigerator lines discharge, and for many other purposes.

The subject of the disposal of sewage and surface water collecting at points below the sewer level has become a very important matter, and as it relates to large work, will be taken up at a later point, in a chapter devoted to that subject. It will readily be seen that in handling large volumes of drainage from public toilet rooms located underground, the use of any such device as the cellar drainer would be out of the question entirely, such work needing powerful apparatus working on a different principle, and often required to discharge many thousands of gallons per hour.