When a gas pipe has a hole or a break in it, the pipe leaks gas continuously. The rate of this gas flow depends on two factors. A larger pressure of gas produces a larger force expelling the gas. A larger hole provides a greater area over which that pressure can act. You can determine the gas pressure, if you don't know it, using a pressure gauge. To factor in the area, consider the hole's diameter if it is round or estimate its approximate diameter otherwise.
Add 14.4 to the pipe's pressure, measured in pounds per square inch, to convert it to absolute pressure. If, for instance, the pressure is 27 pounds per square inch: 27 + 14.4 = 41.4 pounds per square inch.
Square the diameter of the hole in the pipe. If, for instance, the pipe has a break that measures 0.75 inches in diameter: 0.75 ^ 2 = 0.5625 square inches.
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Multiply together the answers to Step 1 and Step 2: 41.4 x 0.5625 = 23.29.
Multiply the answer by 1,000, a conversion constant: 23.29 x 1,000 = 23,290 cubic feet of gas per hour.