Originally Posted by tadpole
Isn't there a formula that you irrigation gurus use on pipe size reduction to maintain a certain psi. I know on long runs the pipe size must be reduced periodically.
Any good plumbing or irrigation Book will have FRICTION LOSS CHARTS FOR PIPE. Google FRICTION LOSS CHART FOR PIPE OR HOSE ETC. Hose will have more friction loss because it has more twists and turns etc.
As a one time Irrigation contractor I started sizing Pipe from the Farthermost point. As I came closer to my water source the Pipe size increased because I had more sprinklers on the line. The point of reducing pipe size is economic if you don't need 400 GPM at the far end.