About James Grote Expertise Questions concerning irrigation, sprinkler systems, water pressure,backflow preventers, and drainage would be best. Questions about individual plants or shrubs are best left to others.
Experience
Past/Present clients Edward Jones Dome, Christian Hospitals, Barnes-Jewish Hosptials,St. Anthony's Hospital, St.Lukes Hospital Bellerive Country Club, Normandy Golf Course, Emerson Electric, and residential.
Question My water meter is 3/4 and my supply line is 1 1/2".
I have three large pastures (140' x 90' and the other 2 are varied in size-much larger). All pastures slope downward and are below my water meter.
I need to know if the following information that I have been told about my design is true?
I have been told to use 1 1/4" PVC sch. 40. I have, believe it or not, PSI of 190, so I will be installing a pressure regulator and droping that down to about 80-85 psi. I also will install a Reduced Pressure Backflow Preventer, so that I can use 1" globe valves (or should I use 1 1/4" or 2" globe valves?) throughout the system.
I would like to know what brand of valves to use for the Presure regulator (200 PSI), the RPBP, the globe valves and the sprinkler heads. I was told to use Toro Sprinkler heads 2001 series used for golf courses, being that my pastures are deep and they can spray up to 75'. I am placing them at about 50'intervals.
I am only placing two sprinkler heads on one valve? I hope this is correct?
Can I run the 1 1/4" pipe right up to the sprinkler heads (that will be attached to my fence posts) then use a bushing to accomodate a 1" female opening on the sprinkler itself? Or should I run a 1" pipe off the supply line through the globe valve then up to the sprinkler?
Any suggestions and help would be greatly appreciated. I hope I have made sense of my questions?
Answer Deb,
Lot of questions here. I'm earning my money on this one. First of all, lets look at the water pressure. If it is in fact 190 PSI, (and that is the highest I've ever heard of), then you will need to put pressure regulator BEFORE the Backflow preventer because as far as I know the maximum operating pressure of most RP's is 175 PSI. There may be a particular make and model that goes above that, but I don't think so and there wear and tear on the springs and rubber seats in the backflow at 190 PSI would cause a lot of problems immediately.
Now, to get teh distance of 75 feet you are going to be putting nozzles in the heads that put out 35-45 gallons per minute. With 2 heads on a zone you are looking at 70-90 gallons per minute. sounds like a lot of water and it is. The gallons per minute (and pressure) determine pipe sizing.
The one problem I see here is that it doesn't look like you can get that many Gallons per Minute through your 3/4" meter. OK, I looked up the 2001 head and the longer radius is 71 Feet. So you're a little short of the 75 feet, but no big deal. To get the farthest radius you put a 30 Gallon nozzles, you have 60 gallons per minute there. According to my cacilations, there is now way you will get more than 30 gallons per minute, maybe 40 gallons a minute through a 3/4" meter. Even a 1" meter is stretching it, but may work with the extra pressure. So the high pressure will increase the flow and maybe get a 1" meter to flow that much water. The other thing with pipe sizing is you have to look at the Feet Per Second of the water. The guys who make PVC pipe have charts and they like to keep the speed of the water under 5 feet per second. The gallonage is so high that you get 18 feet per second.
So you could take less distance , like 50 ft. radius , and thats will knock down the gallons per minute to as low as 9.4 gpm with the #6 nozzle in the 2001 head to about to under 20 gallons per minute with the #12 nozzle. Which would mean you could keep the meter and space the heads closer.
I also suggest 1 1/2" pipe to the head are at least 1 1/2" pipe out of an 1 1/2" valve and then telescope down to the smaller pipe at a tee or something.
I don't know if I answered all your questions sufficiently. Watts make most of the pressure regulators and they make a good one.
Let me know if you need more info. Jim
