SPRINKLER TALK FORUM - You Got Questions, We've Got Answers

[font='Arial, Helvetica, sans-serif'][size=10]I have a few questions on 2 zones in my design that I wanted to get some opinions on.

Background:
• My house has a 1 inch copper water feed; 52 PSI (measured just before the control valve) and a flow rate of 22 GPM (13.5 sec to fill a 5 Gal bucket measured at the output of the 1 inch control valve)
• I branched out 1 inch PVC just after the water entry to my house for the zone control valves.

1st Zone:
• I had wanted to use 4 Orbit Saturn III gear drive heads on ¾ inch poly pipe on this zone
• If I look at Appendix A, Chart 1, in the Orbit “Sprinkler System Layout & Installation guide” it shows that for a 1” main line SCH 40 PVC @ 50 PSI it should support up to 4 heads; but a ¾” main line SCH 40 PVC @ 50 PSI only supports 3 heads
o QUESTION 1 - When it states “Main line SCH. 40 PVC” do they mean the “line” into your house OR the ¾ inch poly pipe “line” I am running for this zone?
o QUESTION 2 – What do you use for number of heads calculations - PSI or GPM?
• The instructions for the Orbit Saturn III show that @ 50 PSI the head is rated 3.4 GPM. That would imply I need 13.6 GPM (I have 22 GPM)
o QUESTION 3 : Why does it seem that I have an excess of capacity per the GPM calculation – but the Orbit manual table I mentioned above states a max of 3 or 4 heads per zone?
o QUESTION 4 : Would a ¾” ploy line be acceptable for this circuit?

2nd Zone:
• I had wanted to use 3 Voyager II gear drive heads on a 1 inch poly pipe
• If I look at Appendix A, Chart 1, in the Orbit “Sprinkler System Layout & Installation guide” it shows that for a 1” main line SCH 40 PVC @ 50 PSI it should support up to 3 heads; but a ¾” main line SCH 40 PVC @ 50 PSI only supports 2 heads
o QUESTION 5 – (Same as 1 above) When it states “Main line SCH. 40 PVC” do they mean the line into your house OR the “line” you are running for this circuit?
QUESTION 6 - (Same as 3 above) Calculation based on instructions shows 3 heads are 10.2 GPM; why then restricted to 2 or 3 in table I referenced above?
• QUESTION 7 – Is there a disadvantage to running 1 inch poly pipe for this zone? I had read somewhere (which I can’t find now) that you should step down to ¾ poly for each circuit; even if the inputs to the heads are all ¾ inch (I thought there would be additional GPM by staying at 1 inch). Is there an advantage?

Thanks in advance for the info/help!
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Quoted from "Wet_Boots"

You might prefer to use just one model of rotor head for the entire project. Whichever Orbit rotor head is a copy of the Hunter PGP would be your best bet, because they have the best range of nozzles. I expect that's the Voyager, but confirm that, as I don't install Orbit.

Thanks for the tip; but I still need answers to the same questions irrespective of the rotor heads (i.e. Chart questions; GPM calculations vs chart; GPM vs. PSI for number of heads, etc.).