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 hour 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.

Service pipes should never be less than 3/4 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 3/4 in., and for larger stoves, 1 to 1 1/2 in.

Having ascertained the probable maximum quantity required in cubic feet per hour, the diameter of the pipe can be found from the following table. 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.

## Capacity Of Gas Pipes

 Diameter of Pipe.In. MaximumLength.Ft. Capacity per Hour. Coal Gas. Cu. Ft. Gasoline Gas.Cu. Ft. 1/4 6 10 3/8 20 15 10 1/2 30 30 20 3/4 50 100 75 1 70 175 125 1 1/4 100 300 200 1 1/2 150 500 350 2 200 1,000 700 2 1/2 300 1,500 1,100 3 450 2,250 1,500 4 600 3,750 2,500

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 fell of pressure.