Precipitation Rate/Catch Cup Test

I ran my Orbit catch cup test today on all four zones and I wanted to poll everyone that is using Rainbird 5000 rotors. I’m just curious as to what other people are getting with their precipitation rate with Rainbird 5000 PRS+ rotors. My results seem a little low IMO, and I wonder if my radius adjustment is cranked down too much causing it to mist more. I used 12 cups in each zone, ran them for 10 mins, documented mL, ran for 10 more mins, and documented total. Some locations do overlap with another zone, but it’s minimal. Here are my results. I’m also wondering if the overlapping of zones is greatly skewing my results since the lower quadrant isn’t accurate.

Total mL: 270
Distribution Unif: 62%
PR in/hr: 0.25

Total mL: 318
Distribution Unif: 34%
PR in/hr: 0.30

Total mL: 334
Distribution Unif: 53%
PR in/hr: 0.31

Total mL: 278
Distribution Unif: 52%
PR in/hr: 0.26

I have rainbird 5000 rotors and my precipitation rate is low as well. After some research, I realized that these rotors were meant for large radius. Even though my yard is on the smaller side, in some cases the radius is less than 24 feet, the installer placed those rotors and adjusted the radius to the point that there is a lot is mist. I am in the process of replacing them with rotors that are for smaller yards. Hunter PGJ rotors have precipitation rates of 0.6in/hr and is relatively stable with different nozzles/radius.

Also the fact that the uniformity is low might be a sign that the sprinklers layout is not ideal, a square or triangle, with water going from head to head.

I replaced all my hunters PGJ for the rainbird 5000 + PRS SAM with the 2.0 nozzle I just haven’t had the time to do a catch cup test I couldn’t be any happier with the results of this rotors the covers of this rotors are great I also replace all my sprays bodies with the RD 1800 series and the R-VAN nozzles

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Based on Rainbird 5000 spec, a nozzle of 2.0 and pressure of 45psi will cover 37ft radius with precipitation rate of 0.29in/h.
To get around 0.5in/h, you’d need a nozzle of 4.0 that covers a radius of 42 ft!

I do have the 2.0 nozzles installed, I guess I could change those out to put down the water faster, but I think it would be better to have it run longer and get a better soak. I still don’t understand with my new settings why the Flex Daily schedule still wants to run them 6-7 days in a row. Seems like you would want them to run less often but for longer to promote deeper roots.

What did you have your crop coefficient set at ??
My zones runs for 54 minutes each I have cool season grass with sandy loam my grass looks really happy I do some minor tweaks with the crop coefficient

@moisture - I have almost 7000 sq of grass I like how this rotors works the problem I had with the hunters rotors was that the heads got stuck very often and lots of gallons of water was being wasted specially at 5:00 am when no one is paying attention to the sprinkler but again it’s all depends how your system is designed

Crop coefficient : 60

I’m having a tough time figuing out what exact soil kind type I have as well.

Have you try

You can also post pictures of your advance settings and someone on this great community will help you figure out your problem.

Just bear in mind that there is a limit on how many gallons per minute can be supplied to each zone. This is limited by the size of the pipe to the water main. The limit can be around 10-15 gpm. You can do a quick test to figure this out with a 5 gallon bucket.

If you switch your nozzles to 4.0 on all sprinkler heads, you double the flow from around 2gpm to 4gpm per head. If you already have around 5 sprinkler heads per zone, going to a 4.0 nozzle will exceed the max flow possible.

If the rotors are spraying water nicely and without misting, then look at the cause of the low Distribution Uniformity. You should be able to reach a DU of around 0.70. Perhaps you are missing some rotors. The spec assumes a square pattern with head-to-head coverage. Also, another factor is the wind. When you test, it needs to be on a non-windy day. Normally you water at night, when the wind is not strong, and you might also have a wind skip enabled so that you don’t water on windy days. And try to test it early in the morning (closer to watering times) when the demand for water in the neighborhood is not as high as later times.

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I did try this a few weeks ago and it came back with sandy loam, but I find it hard to believe. Our soil here seems like heavy clay, but I have sandy loam plugged in.

I did perform test in low wind early in the morning. I was planning on only swapping out nozzles to a larger size in a couple of heads that do a 360 pattern and one that does around 250 degrees. Looking back at my notes it seems like the low quadrant results are from the edges of zones that overlap with another zone. I did not run both zones and measure, I did each zone separately. Also I’m getting a much smaller amount of water going down close to each head. My cups were 4-5’ from each head and those would average around 15mL in 20 mins. The head placements are in a combination of square and triangle coverage. The longest run between heads in 35’, but most are 28’ or less.

@ox1574 Yeah, you’ll need to work out the numbers to achieve “matched precipitation”. So if you have a rotor with 360 coverage, it will put 1/4 water than one with only 90 (on the same quadrant). So you’ll need to adjust the nozzles and match Precipitation Rate. But here is the issue, with radius between 28’ and 35’, you are already on the lower end of the spec, so you’ll have a hard time to get them matched. Nozzles are cheap, so you can get a few, and probably you can also get some Low Angle for the smaller radius. And experiment to see if you can get it to work without too much misting when you reduce the radius screw.
And for overlapping zones, you’ll need to run both zones to get the right measurements.

Am I correct in thinking that with 1" SCH 40 pipe the max GPM would be 13? For ZONE1 I have 5 heads, 1 does a 360, 2 are 180, and 2 are 90’s. All 5 currently have 2.0 GPM nozzles installed. The rachio app has calibrated that zone and shows it’s baseline flow rate is 6.1GPM. Why would the GPM shown in the rachio app not be closer to 10? If the 6.1 is accurate I should be able to put a 6/8GPM nozzle in the one head doing the 360 right?

@ox1574 What is the size of the pipe coming from the main water line? It might be mentioned on your water bill if you get one. Or you can visually check the pipe coming into your house where you have the water shutoff. Mine is only 5/8" and I measured it to be over 10 gpm. For irrigation, the mainline pipe is larger than the water supply pipe because with larger pipe the pressure loss is less, and pressure is important for sprinklers to work.
In terms of actual flow and precipitation rates, there are many factors that could reduce the flow from theoretical. I think Rachio app uses the square foot of the zone to convert the Precipitation rate to GPM. So how accurate is the area of the zone? Also, what goes in catch cup is less than what the sprinkler head is pushing out because of losses due to misting, wind, evaporation, etc…

Yeah I think it’s 5/8-3/4" copper coming off main line. I have a flow meter installed, so I assumed the GPM was actual coming from the sensor and not a calculation based off of square footage. Yep - just checked bill 5/8" line.

Oh I assumed you didn’t. Because Rachio will estimate the water usage based on square footage if you don’t.
So in that case, your sprinklers are putting less water based on the nozzles you have. There is a radius adjustment screw that can reduce the flow, and maybe you had tightened it too much that it is putting a lot less water? With the distances that you had given earlier, and a 2.0 nozzle, the radius is 37 feet. So when you adjust down to 28 feet (beyond the 25% reduction limit), you might get less flow as your meter shows.

@ox1574 - if you have sandy loam plug-in the AWC is I think 12” inch what I did with my was I increased it to 15” inch root depth I left it at 6” inch allow depletion left it as default and for the nozzle inch per Hour I use the rainbird charts since I have the 5000 series with the 2.0 I have my set at 0.61 but again like I said earlier I haven’t done a catch up test

One thing to consider if you change the nozzle for a much larger one you are taking away pressure from the other heads

I currently have my AWC set to 0.12 in/in and allowed depletion set to 50% on all zones. 3 of the 4 zones are using a 2" root depth and 1 zone (which is new sod) I’m using 1" root depth.