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

I gotcha. I guess I didn't realize the valves in question had flow control. I was assuming that he was replacing all of the valves with flow control valves. I understand now, thanks for the clarification.

Adding a pressure regulating valve would be wasteful because the zone valves in this particular system already have flow controls that haven't been adjusted yet. With a static pressure of less than 80 psi, with a RPZ backflow besides, there is no high pressure the system needs protection against. Your standard brass pressure regulating valve has a very high pressure loss, in comparison to a pressure regulating solenoid valve. And even those are intended for a pressure drop of at least 10 to 15 psi. Maybe this system can afford the pressure drop. Maybe not. But to ignore the flow controls already there on the zone valves would be wasteful.

Ok, suppose you don't have pressure regulated valves. Why would it be wasteful to install a pressure reducing valve on the mainline? Seems to me that it would be more cost effective than replacing the valves. As for the well over 100 PSI, I find that quite frequently irrigation installers will use a pressure regulating valve on the mainline over regulated valves almost every time. Which one is more likely to fail first? If a plastic valve gives way, or the pressure regulator is not set right, bam, there goes all of your heads and pipe about 200 feet into the air. A preset pressure regulator right off of the mainline near your point of connection is far more reliable. Most of them come preset anywhere from 50-70 PSI. Im sorry but I don't agree with you on that one, unless you can show me how it is more effective another way.

Depends on the layout. If I was looking for coverages only between 15 and 27 feet, I'd use the old Toro 300 Stream Rotor heads, which, by the way, have no distance adjustment whatsoever. But they are reliable.

Again, what's your thoughts on using I-20 for short radius from 14 to 27 feet?

Irrigation subject is very new to me and only knowledge I have about them are from reading books and web. I really appreciate comments from you all. The only reason I am here is because you pros are there. I do not want to make mistakes by doing the way I like it. Please provide me reasons for not doing something and I will get it. Like, when you said 100PSI is the range to use Pressure regulator, I understand that. I will try the flow control ajustments on the valves to see if I can get it down to reduce the PSI.

Thanks.

The only time a pro uses pressure regulation is when the supply pressure exceeds 100 psi by more than just a few psi. You can do anything you wish, whether or not it makes any economic sense, but adding pressure regulation in your situation is wasteful. If you want less distance from the existing heads, throttle down the flow controls on the zone valves. That's one reason why they're there. Don't ask questions about it, just go out and try the adjustments.

I might consider installing a pressure regulator (or ICV valve with accuset) on main line. This also will function as a master valve. ICV being a regular valve, if I am loosing too much pressure, I could take Accuset off the line and use it just as a master valve.

Regarding the I-20 radius, I went by the specifications provided by Hunter. They say I-20 is the one for all rotor. There are short radius nozzles available for I-20 which can go down to 17 feet. I am using the breakup screws on them to get down to 14 feet.

Unless the nozzles are blowing fog, just use the breakup screw on the rotors, or perhaps you need to install larger nozzles, to get a higher flow and lower pressure, with reduced spray distance as a result. If you were expecting the rotors to be spraying at radii of 14 to 27 feet, you have misread the performance charts. You normally are calling for a I-20 to spray 35 feet or even more.

You could just put a pressure regulator on your mainline right after your point of connection, and simply use the set screw on that to regulate your PSI. That would be cheaper than replacing all of your valves.