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

I have a ten year-old Hunter lawn sprinkler system and it worked fine for about two years. Since then its been a steady repair schedule ( every spring clean or replace dirty diaphragms, flush the valve, reassemble ). The contractor put in low-end Hunter parts --- 1" SRV valves and PGP heads. I've been systematically replacing the PGP's with Orbit Voyager II's and have yet to have a problem with any of the Orbits which I can pick up at any big box store. I'm very much a DIY'er and understand the mechanics of the sprinkler system and have done all of the controller programming myself.

Other details --- I have a well that delivers 3 gpm at good pressure up to 50 psi and the system normally shows ~ 25 to 30 psi when a zone is running. I have 15 zones with approx. 4 heads per zone. Yes, 3 gpm is very low for a well but I am lucky to get that where I live ( central Kansas ). Well is reasonably clean with no sediment and only a slight hint of shale.

The SRV valves have been nothing but trouble and I want to upgrade from these. A common problem is that several zones will not have the valves fully close and I end up with up to half of the zones dribbling out water at the same time. This makes for a few very green and lush 3 foot circles in my yard around the heads and everything else burns up. The SRV's are glued in place so if I go with a completely different valve I'll have to cut them out which I am willing to do but if I go that route I want to install a valve that will be relatively maintenance free. I'm okay with cleaning and replacing diaphragms as needed.

What would be some suggestions for replacement valves? I don't mind spending up to $30 per valve ( 15 total ) or a couple of bucks more if I get some bang for the buck. The easy route would be to buy Hunter PGV's and just replace the new tops / diaphragms and leave the old SRV valve bodies in place. I would only do this if I could be convinced that this would give the dependability I'm looking for. Has anyone had good results doing this? Also my well needs time to recharge between zones so I have a 20 delay programmed before the next zone starts. I mention this because I wonder if it would be good to have flow control on the valve, be it Hunter PGV or another brand. Other than the PGV's, what would any of you recommend for a replacement valve? Please let me know your opinions.

The "slight hint of shale" I referred to is a very slight "slimy" film, not bits and pieces of shale. I have pulled the pump a couple of times and each time the inlet screen on the pump has been very clean. You think the "film" is clogging the holes in the diaphragm not allowing the valve to close? Would flow control take care of the non-closing valve? If I try the strainer route do you have a particular compact model in mind? Thanks.

Quoted from "Central Irrigation"

You should save your money, and instead, install a 100 mesh inline filter to your sprinkler supply line. That shale you referred to is the sole reason your valves are failing.

Edit: It is possible that your systems dynamic pressure is too low to operate the valves effectively. I wpuld say, based on your numbers, you should check for any and all leaks. PGP heads are notorious for leaking while operating, and can rob a system of critical pressure. Personally, since you state this is a recurring issue, i am more apt to believe that this is a water quality and design issue, more so than a component issue. Although, leaky heads and the like would exaserbate the problem.

Anybody else care to comment?

It is true that I have noticed the PGP heads leaking around the valve body seal but the ones that have been replaced by Orbits do not leak nearly as much. I have a few heads left to replace with Orbits this spring. That being said, the system works fine after I go through all of the valves and replace the diaphragms, but I shouldn't have to be doing this as often as I do. The main problem that happens is that several zones are not shutting off properly ( even with a 20 minute delay between zones ) and this leads to wet spots in the yard around the heads with not enough pressure to operate the one zone that should be sprinkling. I have good pressure when the valves operate properly but it just doesn't happen for very long after going through the valves. What is your opinion on replacing the SRV tops with PGV tops with flow control ( easiest to do without cutting out and going with a different brand ) and also installing the 100 mesh filter as you mentioned above? Thanks

Quoted from "Wet_Boots"

Flow-control valves are wanted here. Also, filtration should always be employed on well water. It isn't that every well gives damaging amounts of particles and sediment, it's that the hassles and expense of cleaning things up, after the fact, are far beyond what it costs to filter the water in the first place.

Is there a pressure tank in the well-water supply?

Will flow control adjustment help the diaphragms to close ( by putting a little more pressure on the diaphragm spring ) when the zone turns off at the controller? Also, there is no pressure tank on the well water supply. The well is for irrigation only, and my house is connected with city water.

Quoted from "Central Irrigation"

No, it does not add pressure to the spring. In fact it actually does the opposite. The flow control actually makes contact directly to the diaphragm, not through the spring. A flow control only limits how far a diaphragm can open, thus controlling how much water can can flow through the valve. There is a case that could be made that if using a flow control, the diaphragm would have less distance to travel in order to close. However, the diaphragm will only open as much as the flow dictates. So i guess i fail to see how a flow control would help.

Okay that makes sense to me if the flow control plunger isn't operating through the spring but on the diaphragm itself. That's why I'm asking these questions, just trying to learn and draw from others' experience. I have a lot of experience with industrial bypass and pressure regulating valves that do operate by loading / unloading a spring. The springs in these control valves are pretty flimsy compared to most springs, and it doesn't look like manufacturers offer any stronger spring for operating. They diaphragms appear to engineered to close (make contact with the valve seat) with the spring & gravity before being held closed by the larger surface area of water from above the diaphragm.

Are most manufacturers diaphragms about the same as far as quality or forgiveness when it comes to closing?