This is generally used as a reference for the pipe, although the interior size of the pipe is less. at the generator is needed? Section 1, supplying outlets A and B, or 115 cubic feet per hour … For example let's use if using an electrical appliance on a very long extension cord. If you’re going to be working with natural gas it’s important to be familiar with the sizes of natural gas pipes and the amount of gas that can pass along them for different lengths. What has to be done is to reverse engineer the // -->