# Too many sprinkers on one zone?



## TenaciousM (Sep 25, 2019)

I have these orbit metal head pop up sprinklers in my yard. My backyard is fairly small and I have 6 on one zone and 8 on the other. The 6 zone seems to have good pressure. The other zone with 8, struggles to get the heads fully extended and the spray is kind of poor.

These are the types of heads I have.
https://www.amazon.com/Orbit-54118-Pop-Up-Sprinkler-Pack/dp/B000BQUTTU/ref=sr_1_4?crid=2FHCHVJ9Z2CW&keywords=orbit+metal+sprinkler+head&qid=1569429913&s=gateway&sprefix=ORBIT+METAL+HEAD+%2Caps%2C197&sr=8-4

Is 8 too many for one zone? I removed two of them and put caps on those lines to see what would happen and the other 6 work fine now. Could it be that these sprinklers don't perform well and a different head would allow me to use all 8?


----------



## Dkrem (Mar 16, 2019)

Do those have replaceable nozzles that can be taken one size smaller ?


----------



## TenaciousM (Sep 25, 2019)

I'm not sure. Would that increase the pressure?


----------



## Dkrem (Mar 16, 2019)

Short answer, yes. It would reduce the flow demand of the zone, similar to what you did by capping two of them.


----------



## TenaciousM (Sep 25, 2019)

Thank you for reaching out. Do nozzles look to be replaceable to you?


----------



## TenaciousM (Sep 25, 2019)

What size nozzle would I be looking to replace these with?


----------



## Dkrem (Mar 16, 2019)

Don't know, the model you linked doesn't have GPM listed. Time for you to do some research.


----------



## TenaciousM (Sep 25, 2019)

OK, so I just need to find a lower GPM nozzle if they have one. Gotcha. Thank you for your help, I sincerely appreciate it.


----------



## Dkrem (Mar 16, 2019)

Yep, that's it, sorry if it didn't make sense. Ideally if you can find out the rated GPM of those then you know 6* that gpm is about the total usable flow you have available. Say they are 2gpm units, that means 12gpm works and 16gpm (current) starves you of pressure. Then ideally with 8 heads in that zone if they all sprayed the same pattern you'd need 12/8 = 1.5gpm nozzles in each.


----------



## TenaciousM (Sep 25, 2019)

OK, I found out what the different heads run for GPM. When I get home tonight I'll take a look and see which color I have, I think I have the black ones currently.


----------



## hsvtoolfool (Jul 23, 2018)

To gain some perspective on the Orbit nozzle flow rates...

* Orbit Black 360° 16 ft at 30 PSI = 3.12 GPM (8 x 3.12 = ~25 GPM on 1 zone)
* Rainbird HE-VAN 360° 15 ft at 30 PSI = 3.7 GPM (8 x 3.7 = ~30 GPM on 1 zone)
* Hunter MP2000 360° 15 ft at 30 PSI = 1.2 GPM (8 x 1.2 GPM = ~10 GPM on 1 zone)

Mind you, using eight 360° nozzles is the worst-case value. A 180° nozzle flows exactly half of the 360°, a 90° flows one-quarter, and so forth. I just chose the 360° nozzle for an apples-to-apples comparison across brands. To calculate each zone's total flow in GPM, you need to sum the spray patterns you actually used for each head. You may use nothing but 180° nozzles, so the total GPM would be half the values my above examples.

Hopefully, you can run the standard "5-gal Bucket Test" directly from the main irrigation supply pipe (not a hose bib!). If you can fill a 5-gal bucket in 12 seconds or less, then you can flow 25 GPM. Likewise, a 10 second fill for a 5-gal bucket is about 30 GPM. A 30 second fill for a 5-gal bucket is 10 GPM. No that hard, eh? Granted, I haven't had enough coffee yet, so @g-man or someone else should verify my math. But you get my point. The water supply at the curb determines the maximum flow at the spray heads. Since your system is already in-ground, you must choose nozzles to fit the feasible flow rates.

For more details on GPM, PSI, and water hammer, go to Jess Stryker's awesome (and free) irrigation tutorial web site....

https://web.archive.org/web/20190125104935/https://www.irrigationtutorials.com/

I hope this helps!


----------



## TenaciousM (Sep 25, 2019)

Thank you both for all your advice. You have both helped a ton and because of that I know so much now, I'm looking at different heads to make all this work.


----------



## ShilpaMann (May 12, 2018)

I very much suggest doing the bucket test a suggested above. I have an irrigation system that was not functioning well when I bought the house. I was trying to resolve a bunch of issues with coverage, then I came here and heard about the bucket test; eye opening. Turns out, my main shutoff to my home (3/4") wasn't the best, but the winter shutoff flowed VERY poorly.

With my old 2 valves: 5gal bucket filled in ~38s. Changed the winter shutoff valve to a ball-valve, ~18s to fill the bucket. Changed the main shutoff: ~14s. Resolved 100% of my flow issues at a cost of 2x 3/4" sharkbite valves.


----------



## TenaciousM (Sep 25, 2019)

Wow, that's an eye-opener. I will check my flow to see. Where do you locate your valves to do this type of upgrade?


----------



## ShilpaMann (May 12, 2018)

You should be able to find these valves pretty easily.

The main shutoff for your home would be very close to your water meter. I'd personally not suggest changing this one because, normally, you have to call the city to turn off / turn on your water (for a fee), and your existing one is probably pretty good. I changed mine because it was leaking, but I didn't want to pay the city, so I just cut off the old valve, and with water blasting out of the pipe, sanded the edges and deburred the inside ... and pressed a sharkbite on. I should have videotaped it.

As for the irrigation valve, depending on how stuff is setup, it is probably the last valve before the pipe goes outside. Again, no need to worry much about it if you have adequate flow. I'd expect the valve to be labelled as the irrigation shutoff.

Regardless, you will want to do a flow-test with whatever you currently have. If your house is new-ish, there's a decent chance you already have good quality valves. My house was built in 1970, and the irrigation system was probably installed by the homeowners (based on the shoddiness of the install); the irrigation shutoff was basically the cheapest valve they could find.

Edit: For the 5gal bucket test, measure time to fill. 300/<that time> = GPM. As the above example, 300/12s = 25. 300/30s = 10GPM

Another edit: That URL linked above goes to the web archive. To go to the actual page itself: http://www.irrigationtutorials.com


----------

