Using non MPR rotor heads in one zone
+1 805-541-1003
  Nov 22, 2022
  2 Replies
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I am using Rotors 8000 and 5000 series in a project..
is there any technical issue with using each series on a separate zone, but the heads of each of these series are not MPR nozzles?

The system is sized fine and I haven't faced any problem in using them this way?
but the client is saying this is wrong and not able to understand why its wrong..

Can anyone help please?

Nibal Ata set the type of the post as  Issue — 3 days ago
It is possible to place non MPR versions together on the same zone, but you need to be the one placing the proper nozzle in the proper location in order to still accomplish what an MPR nozzle is doing. Since a Quarter head will complete a pass 2x faster than a half, and 4x faster than a full, This would require you to:

-Reference the performance chart of the given head
-Look at each nozzles precip rate (within a given design pressure)
-Determine what nozzle will be used for the Quarter, Half, Full locations on the plan
-Ensure that the Quarter nozzles precip is 2x less than the Half, and the Half is 2x less than the full.
-Only place the Quarter, Half, and fulls with that respective nozzle.

If you cannot do this, and there is no nozzle for a one of those arcs because the precip wouldn't match, then you would not want to put these on the same zone.

Most of the time, it is just easier to place all Quarters on a zone, all Halves on a zone, and all Fulls on a zone (still being consistent with the nozzle used).

If you have an example plan you want to share for others (or us) to see and chime in on, please feel free to attach here.

Hi Nibal,

As always, Jake is a wealth of information. Well said Jake. I'm wordy and unclear, but I'll try and add something to this which may also help.

I've never seen a plan that uses the same nozzle to achieve a precise radius and have them be on separate valves to achieve the most uniform distribution. It would be possible, but not very cost effective. But I have seen many, many designs (say ballfields just to make it easy) that irrigate all of the full heads on their own valves and mix the halves and quarters together on another lateral.

Note that Jake left out one issue with mixing non-MPR heads. The larger nozzles have a further throw (radius). So if you are using them to irrigate the same area (distance between heads), you will usually need to use the defusing screw on the larger nozzle. This reduces the radius, but does not reduce the flow resulting in a higher precipitation. Areas being irrigated by those heads will get more water than the others even if you are using the the head that is designed to reduce the flow by half.

We usually use a minimum of two valves to irrigate a large area. for example, to make it easy let's say that we're irrigating an irregular lawn area which is about 60' feet wide. I'd probably use the Hunter I-20's with a 1.5 nozzle in areas closest to 90 deg., 3.0 nozzles closer to 180 degrees, and 3.0's as full circles. I'd put the full circles on their own valve. If the area only has one or two fulls, I may use a 4.0 knowing that since I'll be defusing it, the precipitation will be higher.

Remember, we do not live in a perfect world. We can strive for very, very good, but those who are perfectionists are never satisfied. You are your client's consultant. You're design will determine the cost and efficiency of the system. While you could have every head variation served by a separate valve, the distribution would be awesome (still not perfect), but how much more will that cost your client? Be a good steward and serve your client well.

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