Hello, I’ve seen a few posts regarding this topic but I can’t seem to grasp the concept of it. I have a main steel pipe x diameter providing 100psi of air to 6 smaller lines attached to it. At the end of these lines are valves. Is there a way to calculate the drop in pressure if I opened up 1 valve ranging from 0-60% if I know the orifice diameter? Moreover, could I find the drop in pressure if I open up multiple valves? Much help is appreciated.