Example

What diameter of pipe should be used to supply three ordinary burners, the length being 00 feet?

Solution

The quantity consumed will be 3 X 5 = 15 cubic feet per hour. The table shows that 3/8-inch pipe can be depended upon to deliver that quantity of gas at a distance of 20 feet only, therefore, it will not serve properly to carry 60 feet. The 3/4-inch pipe is evidently too large, therefore, the intermediate size-1/2 inch in diameter-may be used. Ans.

When carbureted air, or gasoline gas, is used, no distributing pipe should be less than 3/8 inch in diameter.

214. Drainage Of Pipes

Drainage Of Pipes. Illuminating gas nearly always contains a small percentage of watery vapor, and this condenses upon the interior of the pipe. The condensed water will flow to the lowest point in the pipe, and if no provision is made for its removal, it will accumulate to such an extent as to close the passage and stop the flow of gas.

Therefore, all horizontal pipes, unless very short, must be so inclined that they will drain properly. All the branches of a riser must be inclined to drain back into it, or, if the branch be very long, it may be inclined so as to drain into a drip cup at some intermediate point. Usually the whole system of house pipes is arranged to drain back into a drip cup, or siphon, at the meter.

Drip cups must always be located at some point where they can be got at and emptied without difficulty.

Gas pipes composed of lead or other soft metal must be guarded against sagging by running them upon a ledge or shelf. Every sag operates as a pocket to collect water, and if the depression of one of the sags equals the diameter of the pipe, the accumulation of water will eventually choke the pipe and stop the flow of gas.

215. All gas-pipe fittings smaller than 2-inch should be made of galvanized malleable iron reinforced with heavy beads around the screwed sockets. Larger sizes may be made of cast iron.

Elbows, T's, and other fittings should stand clear from the studding and joist, whenever practicable, so that all of the joints may be accessible for the purpose of testing.

Changes in the direction of small pipes should be made by bending the tube, if practicable, instead of using an elbow. Elbows and other fittings, to which side lights or brackets are attached, should be provided with flanges or lugs, and should be firmly secured with screws to solid woodwork, or, in case of brick walls, to wooden plugs driven into holes drilled in the wall, or to wooden blocks embedded in the wall for that purpose, so that the fixture will not wabble.

The nipple for a side light or bracket should project from the wall at a true right angle to a distance of not less than 3/4 inch, and not more than 1 1/4 inches. The nipple should be screwed tightly into the fitting, and a cap should be screwed on the outer end of it. This cap should be screwed up with only a moderate force, so that it can be easily removed at any time without danger of loosening the nipple from the fitting.

Drop nipples, which are to support chandeliers or other hanging fixtures, should hang perfectly plumb, and in case of a flat ceiling should project from 3/4 inch to 1 1/4 inches from the surface.

216. The proper mode of supporting a hanging fixture is shown in Fig. 77. The weight of the fixture is carried by the wooden block a, which must be made strong and be well secured to the joists b, b. The lower block c serves to guide the drop piece d and prevent it from swinging in any direction. Care should be taken to make the drop piece perfectly plumb. When the nipples or drops for the fixtures are all in place, they should be tested to find whether they are square or plumb. This may be done by attaching a straight piece of pipe a foot or so long to which the square and level may be applied, or a plumb-bob may be used.

Fig. 77.

217. The gas pipes should be placed in a new building as soon as the walls are up and the rough timbers of the floors and partitions set, but before the floors are laid or the lathing done. When a gas pipe runs parallel with the floor boards, as shown at e in Fig. 77, the board which covers it should have the lower flange of the groove removed, so that it can be readily taken up when desired. If the pipe runs cross-ways of the floor boards, a loose piece should be provided in the floor over every principal elbow or T, so that they can be got at easily in case of repairs or leakage. The loose boards and covers should be fastened in place with 2 1/4-inch screws. Brass screws are frequentlyused for that purpose, as they will not rust.