Hi, everyone. This is my first post so I figured I'd introduce myself very quickly before I get to the problem. My name is Matt and I'm a first year engineering student at Oregon State University. I've read quite a few topics here, but this is the first time I've really joined in on anything. I'm hoping to make that a more regular occurance as my knowledge grows. 1. The problem statement, all variables and given/known data With a given flow rate of 26 CFM of air and a pressure differential of 1.5 inches of Mercury between the start and end of the pipe, what is the inside diameter of pipe is necessary to maintain a flow velocity of 300 feet per second, assuming there are no losses along the length of the pipe. 2. Relevant equations This is the part I need help with. I'm not sure where to start. 3. The attempt at a solution I will attempt it as soon as I know which equation(s) to use.