Description of the Process of Manufacturing Coal Gas, for the Lighting of Streets Houses, and Public Buildings / With Elevations, Sections, and Plans of the Most Improved Sorts of Apparatus Now Employed at the Gas Works in London and the Principal Provincial Towns of Great Britain; Accompanied With Comparative Estimates, Exhibiting the Most Economical Mode of Procuring This Species of Light

by Friedrich Christian Accum

All branch pipes before they are fixed for conveying gas, must be proved by condensing air into them by means of a condensing hand pump. The pipe should be placed in a trough of water, the leak will then be easily observed by the air bubbles which rise through the water whilst the air is condensed in the pipes.

All branch pipes should have a rectilinear course; pipes that are twisted have an unsightly appearance.

All pipes should have a descent of no less than a quarter of an inch in four feet.

The seams or brazed part of the pipes must always be out most and not towards the wall; because if a leak should happen to take place in the brazed part of the pipe, it may then be easily discovered and more readily repaired.

When all the pipes have been furnished to a house or place intended to be lighted, the whole system of the pipes should be examined with the utmost rigour, to ascertain whether all the junctures are air tight. This should be done by condensing air into the pipes by means of a condensing syringe, and if the piston of the syringe lowers after condensation, it is a sure indication that the pipes are faulty, and consequently totally unfit for receiving the gas. The leak may be detected by passing a lighted taper carefully along the whole extent of the pipe filled with condensed air, when the flame of the taper will be affected as it passes over the faulty place of the pipe.

The aperture from which the gas can escape may however, be so small, as to render it a matter of difficulty to discover it in the manner just stated; but when the pipes are filled with coal gas, the escape of it, when all the stop-cocks of the lamps and burners are shut, will soon become obvious, by the peculiar odour of the gas, if the apartment, or place, where the pipes are placed, is suffered to be closed for about twenty-four hours. The gas should not be introduced into pipes in which any defect of this kind is found, until it be completely removed. The most severe trial to ascertain the air tightness of any system of pipes is, the trial by exhaustion, by means of an air pump, for the guage of the pump will discover the minutest leak, which the preceding method of proving pipes can not discover.

All pipes after being proved should be painted of the same colour as the surface to which they are affixed.

The whole system of pipes should incline to one or more places, so that any moisture that may happen to accumulate in the pipes, may collect at such places, whence it may be readily removed by opening a screw plug adapted for that purpose.

All the different junctures of mains and branch pipes, should be effected by means of connecting pieces, so that any part of the system of the pipes, or any separate branch pipe may readily be detached, and put up again if occasion should require it; fig. 19, [plate V.], exhibits this mode of connecting gas pipes by means of union joints. A, B, C, D, E, shows a gas pipe with its union or connecting joint, divided into its separate parts. D, is a collar of leather, which passes over the part C, of the union joint, close up to the shoulder of the joint; the opposite extremity of the pipe may be inserted into the socket B, so that the shoulder C, comes in contact with the fillet or rim in B, to prevent it passing over the shoulder C, when B and E are screwed together. The latter part of the pipe is furnished with a male screw to correspond with the thread in the collar B. The shoulder piece C, is of rather a larger diameter than the bore of the tube A, with which it is to be connected. The short piece E, furnished with a male screw, is of the same diameter as the part C. The pieces C, and E, of the pipe are soft soldered, one to the tube A, and the other to the tube E, but previous to soldering on C, it is necessary that the socket should be inserted into the tube A, it will then be ready for connecting, as will become obvious by inspecting fig. 20, which shows the various parts of the union joint fitted for use. It is evident that if the extremity D, in the pipe B, be brought close to the pipe E, and if the socket C, be moved along the pipe A, and screwed upon the male screw at D, as far as it will go, the face of the part D, must press close against the leather collar which is placed on E, and render the joint gas tight. These kind of joints are very convenient for circular bends, fig. 22, and T, pieces, fig. 21. The T pieces, fig. 21, are very useful for collateral branch pipes, either for the same or of a less diameter as the pipe, from which they proceed, so as to branch off at right angles.

Fig. 22, is a quarter circular bend; it is convenient for adapting tubes along the angular parts of rooms, and to all such situations where the tube is to have a sudden circular course. Small copper tubes may be readily bent to the required angle without breaking, but if a tube should terminate in any angular part of a room, in that case a circular bend furnished with a male and female screw, is convenient for connecting the pipes together.