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The number of gaslights required to properly illuminate a room depends on its size, condition of wall surfaces, etc. The reflection from the walls in small rooms is proportionately greater than in large ones, and hence a smaller number of burners is required in proportion to the floor space. A 5' (cu. ft. per hr.) batswing burner is assumed to give a light of 16 c. p. under a pressure of .5 in. of water.
For large rooms, such as a church, etc., the proper illumination will be furnished by using one burner to each 40 sq. ft. of floor. If there are balconies, etc., extra lights must be provided according to the same rule. For smaller rooms,
Gas Pressure. Inches of Water Column.
CANDLEPOWER OF 4-FT. UNION JET BURNER AT DIFFERENT PRESSURES.
NOTE.-The best pressure for ordinary illuminating gas is 5 in. of water.
such as are found in ordinary dwellings, the proportion may be one light to about 80 sq. ft. of floor. The amount of light required is, therefore, from .4 to .2 c. p. per sq. ft., according to the size of the room.
If incandescent gaslights, such as the Wellsbach, are used, the number of lights may be much less, as these lights furnish from 50 to 60 c. p. on a consumption of about 3 cu. ft. of gas per hr., at a pressure of .5 in.
The amount of illuminating gas consumed in an ordinary burner depends on the pressure of the gas. An increased consumption of gas does not correspondingly increase the supply of light, as will be seen by the preceding table.
Diameter of Pipe. Inches.
SIZE OF PIPES.
Each pipe must have enough capacity to supply all its burners when they are in full operation. Allowance must also be made for all heating and cooking apparatus likely to be required. The quantity required for lighting may be reckoned as 5 cu. ft. per hr. for each burner, unless otherwise given. The actual quantity required by improved burners, however, differs so much that it is impracticable to compute the volume required by merely noting the number of burners and multiplying this number by 5.
CAPACITY OF GAS PIPES.
Service pipes should never be less than in. because of liability to chokage, and, if of iron, it is advisable to make the diameter at least 1 in. For small cook stoves, the supply pipe should be at least 4 in., and for larger stoves, 1 to 1 in.
Having ascertained the probable maximum quantity required in cubic feet per hour, the diameter of the pipe can
be found from the table "Capacity of Gas Pipes." If the length of the proposed pipe exceeds the maximum length given, the next larger size pipe should be chosen. If the pressure exceeds 2 in., the principal pipes may be reduced one size. If the pressure is less than 1 in., all pipes must be increased one size, and with very long pipes, the diameter will require to be increased still more. When gasoline gas is used, no distributing pipe should be less than in.
In this table, the pressure is assumed to be about 2 in. of water. The quantities stated are those which the pipes will deliver at the burners without objectionable fall of pressure.
INSTALLATION AND TESTING.
The pipes used for the distribution of gas in buildings are standard plain wrought-iron or steel pipe.
If the location of the pipes is not shown by the architect, then the gas-fitter must use his own judgment in determining their position. He should be governed by the following considerations:
1. The pipes should run to the fixtures in the most direct manner practicable.
2. The pipes must be graded to secure proper drainage without excessive cutting of floorbeams, or otherwise damaging the building.
3. Pipes that run crosswise of floorbeams should be laid not more than 1 ft. from the wall, to avoid serious injury. to
4. Fixtures should be supplied by risers rather than by drop pipes, as far as practicable.
5. All pipes should be located where they can be got at for repairs, with the least possible damage to the floors or walls.
6. The fittings should be malleable-iron galvanized, beaded fittings being preferable to plain ones. Plain blackiron fittings should never be used on important work.
The fittings commonly used in gas-fitting are shown in the accompanying illustration.
Their names are: a, quarter elbow; b, tee; c, street elbow; d, cross; e, elbow with side outlet; f, right-and-left coupling; g, reducing coupling; h, cap; i, male and female extension piece; j, plug; k, waste nut; l, drop elbow with female thread; m, drop elbow with male thread; n, drop tee with female thread; o, drop tee with male thread; p, drop elbow with male thread, left flange; q, male chandelier loop; r, drop elbow with long outlet piece; s, chandelier hook, female;
t, pipe strap; u, locknut; v, long screw. The flanged fittings can be had either right or left, and also with male or female threads.
The threads on a " gas pipe will sustain a weight of about 5,000 lb.; on a " pipe, about 7,000 lb.; and on a " pipe about 9,000 lb. Hence, gas pipes securely anchored will easily support any reasonable weight of chandeliers attached to them.
PIPING GAS RANGES.
The size of single lines of pipe run from or near a gas meter to a gas stove or gas range should be in accordance with the following table:
SIZE OF PIPE FOR GAS STOVES AND RANGES.
As soon as all the pipes are in place and are properly secured, the system should be tested to find if it is gas-tight. Air should be forced in the system until the gauge indicates 15 or 20 in. of mercury, or 7 to 10 lb. per sq. in., the pressure being continued for about 1 hr.; if the gauge shows a falling off in pressure of more than in. of mercury, or lb. per sq. in., the system cannot be passed as perfect. The mercury-column differential proving gauge is well adapted for testing gas pipes, etc. that are to be made air-tight; common spring gauges are unreliable.
The extent of a leak may be judged by the rapidity of the fall in pressure, but its location must be found by the sense of smell. For this purpose a small quantity of ether should be introduced into the pipes. The vapor of the ether will diffuse throughout the system and escape from the leak, where it will be detected by its odor. The gauge should be provided with an ether cup especially for testing purposes.
In the case of large buildings, it is advisable to test the