Not a homework problem, personal project. High all, this is my first post. I am seeking information on how to calculate the pressure needed in a single pipe, closed at its end. The pipe will be used in a misting system for aeroponics [veggies, not cannabis! :-) ]. I am assuming a fixed radius for the main pipe, and misting nozzles with a radius of about half that (however, the total flow will be restricted heavily by the porous exits of each valve). Currently, my misting pipe will have two valves, evenly separated from the open and closed ends of the pipe and from each other. The pipe will run parallel with the ground. Valves are attached to the top of the pipe, facing upward. My question is how to go about roughly calculating the total pressure required for causing the valves to mist, and the pressure drop across each valve. I am assuming laminar flow, and that friction and gravity effects are mostly negligible (I will be multiplying the required pressure by some factor and selecting a pump based on this).