Anyone Familiar With Irrigation Indexing Valves?

npalen · Oct 21, 2021

https://www.fimcomfg.com/product/1004-4-outlet-indexing-valve-irrigation/

Installed this valve recently to separate a sprinkler zone with 8 heads into two seperate zones but its not working. The manufacturer suggested changing the stem and disk assembly to the low flow version for under 10 GPM pump output. We did this but still can't get the valve to index from one zone to the other.

The system uses a 1/3 HP submersible pump with pressure tank and the zone valves are the conventional solenoid type with a rainbird controller. I don't know the pump output in GPM and PSI but assume that it is over 10 GPM as it runs the eight gear drive heads.

The reason for installing the index valve was to replace a pair of ball valves that "split" the zone manually.

Wondering if anyone might have some suggestions on further troubleshooting.

Roadworthy · Oct 21, 2021

I suggest measuring the actual pump output. A five gallon bucket and a garden hose should serve the purpose. The indexing valve appears to work by flow volume rather than by pressure. Your flow and pressure will be a function of the pump and how far it has to push the column of water to get it to the surface. Is there a chance the valve is defective in some way?

npalen · Oct 21, 2021

Thanks for your feedback I would really like to know the volume of the pump output and at what pressure that volume is produced. I've done the bucket method a few times in the path for measuring flow but it is difficult to measure the the output of eight sprinkler heads running at one time. I'm know it can be done and also need to install a pressure gauge.

Always a chance that the new valve might be defective and would try a different one but its all "hard plumbed" with 1" PVC.

3Ts · Oct 22, 2021

What is the purpose of the pressure tank in your sprinkler circuit?
Are you aware that the indexing valve has to have the pressure and flow of the incoming water go to zero (0) before it will switch to the next circuit? Pressure tanks are normally in the system to supply water (flow & pressure) when the pump is off. In normal usage, this means your pressure tank will have to fully drain below the pump cut-in limit switch in order for the valve to switch. Normally there is no pressure tank put in sprinkler circuits.

3Ts · Oct 22, 2021

Also, what is the reason to have both solenoid valves and an indexing valve? How about putting up a diagram of your sprinkler system from the pump out to your first sprinkler head, that would help us understand what you're doing a lot better.

npalen · Oct 23, 2021

3Ts said:
What is the purpose of the pressure tank in your sprinkler circuit?
Are you aware that the indexing valve has to have the pressure and flow of the incoming water go to zero (0) before it will switch to the next circuit? Pressure tanks are normally in the system to supply water (flow & pressure) when the pump is off. In normal usage, this means your pressure tank will have to fully drain below the pump cut-in limit switch in order for the valve to switch. Normally there is no pressure tank put in sprinkler circuits.

The system used to be manual and the underground pipes and sprinkler zones added later. The pressure tank remains for the occasional use of a connected hydrant but should probably be taken out of the system.

The zone in question has 8 or 9 heads which is too much for the pump output so the index valve is in place to divide the zone into two. The solenoid valve feeding this zone drops the pressure to zero even though the pressure tank is holding pressure to the valve. There is a check/drain valve installed in each of the two zones that the divider feeds to eliminate any back pressure that might keep the divider valve from working.

npalen · Oct 23, 2021

3Ts said:
Also, what is the reason to have both solenoid valves and an indexing valve? How about putting up a diagram of your sprinkler system from the pump out to your first sprinkler head, that would help us understand what you're doing a lot better.

Yes, I need to sketch a diagram but a little short on time right now. (Fall grain harvest)

It's just a submersible pump feeding the pressure tank which feeds the eight zone valves. Just the one zone solenoid valve has the divider valve installed.

It seems like there is just not enough flow pressure to seat the divider valve so that it flows to only half of the zone instead of all the heads at once. The divider valve is supposed to be functioning as a "switchable tee".
The stem and disc in the divider is rated at 5 to 10 GPM which seems well within the pump output.

https://www.fimcomfg.com/indexing-valve-parts/stem-disk-assemblies/