7

Wastepipes ought not to be connected to soil-pipes or to drain-ventilating pipes, or to the traps of water-closets or slop-hoppers, but ought to be kept entirely distinct.

An exception to this rule may be made in the case of washing-up sinks fixed by the side of slop-hoppers; the waste from such a sink may be connected to an inlet arm provided in the side of the hopper above the standing water of the trap.

8

All waste-pipes ought to be adequately supported.

If this is not done, the seal of the traps may be destroyed by the traps being pulled out of shape by the weight of the waste-pipes. In the case of pipes nearly horizontal, the lack of proper support may cause the pipes to sag and thus lead to deposits and ultimate fracture. A continuous bearer of wood ought therefore to be fixed under every part of a waste-pipe which approaches the horizontal.

9

Joints within the thickness of walls or floors ought to be avoided wherever possible; they ought to be in positions where they can be seen and repaired without difficulty.

The waste-pipes from baths are often laid under the floors. This can only be avoided in the case of ordinary cast-iron independent baths by placing supports of wood or other material under the cast-iron feet. If these raise the bath too high for children's use, it is an easy matter to provide a movable step. This raising of the bath not only allows the waste-pipe to be laid above the floor, but affords facilities for dusting and washing the floor under the bath.

10

Overflow pipes from storage or flushing cisterns must not be connected with waste-pipes, but must be carried through the nearest external walls in conspicuous positions to serve as warning pipes.

These pipes need not be trapped, as the traps would probably be unsealed by evaporation; but hinged flaps may with advantage be fitted on the ends to prevent the inlet of air and dust.

Materials

Lead is the material most generally used for waste-pipes. Pipes less than 1 1/4 in. in bore are now seldom fitted even to small lavatory basins, unless these are of an old-fashioned type with a waste-plug 1 in. or less in diameter. The following table gives the weights of ordinary lead pipes per yard, but special weights are made by some manufacturers:-

Weights of Lead Waste-pipes

The weights in column 1 are the least which can be allowed, but it is always better to use stronger pipes, such as those in columns 3 to 5, especially where large volumes of hot water will pass through the pipes. Some plumbers use 2-in. lead pipes, 36 lbs. per yard, for bath-wastes, but this is a waste of material, and the extra weight does not prevent cracking if the pipe is very long and insufficiently supported throughout its length. The main wastes for ranges of fittings are sometimes 3 in. or more in diameter, and may be of drawn lead similar to soil-pipes.

Other materials used for waste-pipes are brass, white-metal, cast-iron (painted, galvanised, glass-enamelled, or otherwise protected), and glazed-ware, but these materials are not adaptable like lead and will never entirely supersede this material. Cast-iron is, however, largely used for the main external waste-pipes of lofty buildings, and, if properly protected inside, is admirably adapted for the purpose, but the branches are generally of lead. The new "Drainage Bylaws" of the London County Council require all waste-pipes from lavatories and sinks (other than slop-sinks), and all traps connected therewith, to be of "lead, iron, or stone-ware."

Cast-iron waste-pipes are now made from 1 1/2 in. in diameter upwards. The intrinsic value of the metal is so small that it is quite unnecessary to use iron less than 3/16 in. thick, although this is often done. The sockets ought to be large enough to give an annular space at least 1/4 in. wide for caulking, and ought to be about 2 in. deep. The following table gives the approximate weights of socketed cast-iron pipes, 6 ft. long, exclusive of the sockets:-

Weights of Cast-iron Pipes

Glass-enamelled cast-iron pipes are made by one firm in 6-ft. lengths of the following weights:-2-in., 24 lbs.; 2 1/2-in., 26 and 28 lbs; and 3-in., 34 and 36 lbs.

Weights of Brass and Copper Pipes per Lineal Foot

Fixing

All joints in lead waste-pipes ought to be plumbers' wiped joints. The pipes may be fixed by means of lead tacks soldered to the backs of the pipes, or by means of clips, which may be of cast-lead, polished or nickel-plated brass, or wrought steel. These are made to fit pipes from 1/2 in. to 2 in. in internal diameter, and for use on the face of a wall or in an angle. When lead pipes are laid nearly horizontal, they ought to be supported on continuous bearers or shelves in order to prevent sagging between the fastenings. This is not necessary in the case of iron, brass, or copper pipes. All internal waste-pipes and anti-siphonage pipes ought to be exposed to view, and may with advantage be fixed on back-boards as shown in fig. 196.

Diameter

The diameter of waste - pipes must be governed to a great extent by the size of the waste-outlets in the fittings from which they lead. It is extravagant to fix a 1 1/2-in. waste-pipe to a lavatory with a 3/4-in. or 1-in. plug. On the other hand, it is a mistake to fix a 1 1/4-in. waste-pipe to a modern quick-waste bath. The rapid emptying of fittings is in many cases imperative, and quick-waste fittings must therefore be used with traps and waste-pipes to correspond.

The traps and waste-pipes of lavatories and of ordinary kitchen and draw-off sinks are generally 1 1/4 in. or 1 1/2 in. in diameter; and those of butlers' and other sinks, and of baths, from 1 1/2 in. to 2 in. in diameter, but traps and waste-pipes up to 3 in. in diameter are sometimes used for modern baths, and have the advantage of discharging the water with great velocity, and of thereby flushing and cleansing the drains. When several fittings are connected to one main waste-pipe, the main need be only a little larger than the branch waste-pipes; a 2-in. main waste-pipe will be sufficient for half a dozen fittings with 1 1/4-in. or 1 1/2-in. branch wastes, as all the fittings will never be used at the same time. When several ranges of fittings on different floors are connected to one main waste-pipe, this should be still larger, but need not, as a rule, exceed 3 in.