Fig. 313   Joints in Cast  iron Drain pipes

Fig. 313 - Joints in Cast -iron Drain pipes.

6. Shape of drain-pipes. We have already laid it down that pipes must be perfectly cylindrical, but it must not be forgotten that the era-shaped pipe, in condemnation of which we have already given sound reasons, still appears in the catalogues of some makers, but with sockets. Although this shape of pipe is theoretically perfect, in practice it does not answer for such small drains a generally used for houses

At the Sanitary Institute Cougress held in Newcastle in 1896,a new form of pipe was introduced by Mr Plummer, F.K.I.15 A., and as it is now upon the market, it will be well to call attention to it. Mr. Plummer was induced to bring out this design by reason of the results of certain experiments which he made upon 6-inch and 4-inch drains, connected with a w.c having a 2-gallon flush; and owing to the amount of deposit left in the drain, he came to the conclusion that a pipe having a more contracted invert would be more eth-cient for the purpose.1 The form of pipe adopted by Mr. IMummer is shown in Fig. 314, the radius of the invert being 1 1/2 inches. This shape follows the design of a sewer thai is very common in large towns, especially in Paris, the invert being the channel for the dry-weather flow. While it has undoubted merits for exceptionally-large sewers, it remains to be seen whether in practice it will satisfactorily keep itself clean in house-drains, owing to the numerous bulky articles which find their way into them. It is claimed by the proprietors that solid mattet in the drains is in continual contact with a stronger and deeper force of water than is the case with a circular pipe of similar diameter. The large upper diameter of these pipes provides for a sudden flood of water in the drain. The pipes roll into and remain in their correct position, and are not top-heavy or inclined to fall to one side, as in the case of the egg-shaped form. The advantages of strength are maintained by the circular form of socket, and the pipes can be connected with existing circular pipes and sockets of fire-clay or iron,Owing to the shape of the pipes, only those which are well formed can be truly fitted together, hence a misformed pipe must be discarded

Fig. 314   Elevation and View of Socket end of Plummer's Drain pipe

Fig. 314 - Elevation and View of Socket-end of Plummer's Drain pipe.

1The results of these experimets will be found in Volume XVII . Part IV., of the Journal of the Smnitmry Institute, and it will he well to compare these with the testa made by a committee of the Sanitary Institute on the flushing of water-closets, and published on the 1st November. 1893. It must be borne in mind, however, that, at Newcastle, the water-supply is in the hands of a company, who limit the flush to water-closets to two gallons. While the question as to whether two gallons are sufficient for the purpose is still a matter of opinion, it most not be forgotten that, in towns where the water-supply is in the bands of the sanitary authorities. the tendency in to increase the flush to three gallons.

7. The jointing of drain-pipes. - For years subsequent to the introduction of earthenware pipe>, the necessity for sound jointing was not sufficiently recognized, in many instances joints being purposely left open in order that the subsoil water might be drained away. It must not be forgotten that drains are of necessity laid quite close to the house, and at a shallow depth, so that in case of leakage the soil around and about the house gradually becomes impregnated with filth, and the vitiated air is drawn into the house by the heat therein. For this and other reasons which have already been pointed out, it is a sanitary necessity of the first importance that the drain must be absolutely water-tight and air-tight.

The material for jointing the pipes should in the first instance be in a soft or plastic condition, so as to be easily worked and made to completely fill the space between the spigot of one pipe and the socket of the other. The cheapest material for jointing pipes is clay, and this is unfortunately still largely used for the purpose in spite of continued protests by sanitary engineers. So long ago as 1878, Mr. Baldwin Latham drew attention to the danger of using this material, as being one of the worst that could be found for the purpose. In his well-known work on Sanitary Engineering, he says: - "We seek the most impervious materials wherewith to construct our sewers, and often spoil their effect by the indifferent manner in which we put the materials together. A soft yielding substance like clay is about the worst possible material that can be used for jointing pipes, as it must be clear that clay is liable to get washed out of the joints, both from the action of the water escaping from the pipe or the water flowing from the subsoil into the pipe. Apart from this, a soft yielding material when used for jointing, notwithstanding however perfectly the work may be performed, will lead to failure, as the weight of the earth covering the pipe causes the clay to be squeezed out of the lower part of the socket of the pipe. leaving an aperture in the upper part through which sewer air and sewage may escape, or water and sand be carried from the subsoil into the sewer. These serious defects in jointing not unfrequently lead to the disturbance of the line of pipes and destroy the regularity of their bed." Mr. De Courcy Meade, the City Surveyor of Manchester, in 1893, when he was the Surveyor of the Hornsey Local Board, in a report upon "Intercepting Traps and Water-tight Drains", likewise called attention to the dangers arising from the use of this material, especially as "cracks will almost invariably appear in the clay filling, as it becomes dry and shrinks".