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OK so I have been planning on instaling my own sprinkler system, and I'm just about to rent the trencher. I had rainbird design the system, and they did an OK job. I have to redesign a few things over. One question is - they would not design my system for a 1" line, they said with my flow and PSI that they had to size it for 1.25", but that I could reduce it after they designed it with no problem. I've got 50 psi and 30 gpm on right from the 1" main line. They have designed a zone to have 10 heads or the 5000 series per zone. They said it was not safe to design a residential system with 30 gpm on a 1" line. I don't understand why it is unsafe. Anyone see an issue with me putting 10 rotor heads on all 1" lines with my pressure and flow?
I can send the design if you want to see it.
In general, you do not want pressure losses in a system's main line, so you don't skimp on that point. Also, the flow of 30 gpm is beyond the usual operating range of one-inch zone valves, so for the sake of maximum economy, system flows would be kept to 20 gpm or less.