water uniformity

Irrigation systems, sprinklers & other watering topics
Post Reply
Topic Author
dbsoccer
Posts: 18
Joined: Tue Aug 03, 2021 7:51 pm
Location: Fort Collins, CO
Grass Type: Blue Grass
Lawn Size: 8000 sqft
Mower: Honda

water uniformity

Post by dbsoccer »

I have been taking further steps this year to "dial in" my sprinklers so to optimize uniformity and, hopefully, be able to reduce water usage and cost. To do so, I've upgraded one lawn area to RB5004, selected the correct nozzle, adjusted angles the radius, etc. RB has a clever tool to assure the head is installed level, etc. So everything was going great and I was into using my Orbit catch cups. And then I started looking at the result and realized, what appears to be, inherent limitations that prevent true uniformity.

To explain my issue/problem I'll use a theoretical lawn area. This area is 30ft x 30ft. It has 4 heads, one at each corner. Each head has the same nozzle and the radius is adjust to assure over the pattern from each head reaches the two corners to the left and right. Angles are dialed in to perfect a 90degree. If one distributes catch cups symmetrically across this area starting with one in front of each head (2ft away per Orbit), and between each head and on the diagonal there will be a cup in the dead center of this area. The center cup receive water from all four corners. Obviously the center of this 30x30 area will receive more water than the sides or the corners. This seems obvious and what is also obvious is there is nothing that can be done to improve the situation unless...

What am I missing? Is there something that can be done to get the amount of water recorded at the cups in the corners to more closely match the center cup?

User avatar
g-man
Moderator
Posts: 14233
Joined: Wed Jun 14, 2017 10:32 pm
Location: Fishers, IN
Grass Type: Front: NoMix Back: Bewitched
Lawn Size: 5678
Mower: John Deere 220E

Re: water uniformity

Post by g-man »

The center will not receive more than the corners in your example. Since it is farther away from the heads and moving, it get less from each head, but in total, that area covered by the 4 heads should get even amount of water. Check the design guide for the RainBird or Hunter that should show this in detail. It was designed to do even distribution.

Topic Author
dbsoccer
Posts: 18
Joined: Tue Aug 03, 2021 7:51 pm
Location: Fort Collins, CO
Grass Type: Blue Grass
Lawn Size: 8000 sqft
Mower: Honda

Re: water uniformity

Post by dbsoccer »

g-man, The example I described is actually a real situation in my own yard. The catch cup in the center collected 41ml whereas four corner cups collected, on average, about 23ml. To the best of my knowledge and experience I had everything 'dialed in' - run time, nozzle size, radius, overlap, angles, etc.

Obviously, the area in the center has the overlap of 4 heads, where as the sides have only two heads and the corners have three. Yet the corners receive the least amount of water. And, after checking all that I knew to check, I repeated the run and got essentially the same results. I even ran the experiment when I knew the water pressure was at a peak. BTW: the heads are the 5004 pressure regulated to 45psi. All nozzles are the same. I also included four more cups (not mentioned above) that were half way between the center cup and the corner nozzle. All four of these cups collected essentially the same amount of water as the center most cup which indicates to me my overlap was in excess of 100% as these cups should only (on paper) received water from three heads. I purposely ran the radius out a bit for a generous overlap to assure I was getting water into the corners from adjacent heads as I knew the corners were being short changed.

Thanks for the feed back. I'll check into the RB and Hunter design guide to see what I can gleen.

Utk03analyst
Posts: 196
Joined: Sat Jun 08, 2019 2:42 pm
Location: Middle Tennessee
Grass Type: TTTF
Lawn Size: 8000
Mower: Push
Contact:

Re: water uniformity

Post by Utk03analyst »

I think you need a 360 in the middle to even it out. The end of a stream has the most water and the head normally puts out the least amount of water next to it. If my geometry is correct the diagonal would be 42 feet. So as you described one head wouldn’t hit all three of the other heads just 2. Before I did my diy install I bought and older irrigation text book of eBay and it always has a center head in a square. The center head would add more water to the corners without adding a ton of water to the center. hope this helps.

I recently had to add a 360 to part of my lawn it’s nearly 45 feet across and my pgp’s span that but I have a corner lot and it curves at the intersection so I couldn’t place my head in the corner and always had a dry spot the 360 evened out my coverage and solved my dry spot problem.

klsmith259
Posts: 101
Joined: Tue Oct 06, 2020 3:00 pm
Location: Atlanta, GA
Grass Type: SPF 30 KBG and Bermuda
Lawn Size: 6000
Mower: HRX217VKA & Tru-Cut 25

Re: water uniformity

Post by klsmith259 »

Utk03analyst wrote:
Tue Oct 12, 2021 10:09 pm
I think you need a 360 in the middle to even it out. The end of a stream has the most water and the head normally puts out the least amount of water next to it. If my geometry is correct the diagonal would be 42 feet. So as you described one head wouldn’t hit all three of the other heads just 2. Before I did my diy install I bought and older irrigation text book of eBay and it always has a center head in a square. The center head would add more water to the corners without adding a ton of water to the center. hope this helps.

I recently had to add a 360 to part of my lawn it’s nearly 45 feet across and my pgp’s span that but I have a corner lot and it curves at the intersection so I couldn’t place my head in the corner and always had a dry spot the 360 evened out my coverage and solved my dry spot problem.
This is the way.

Post Reply