Buying a sprinkler rotor is a daunting process, to say the least. There is an overwhelming amount of information out there, from product information to design information. This glut of information can intimidate even the most stalwart of DIY’ers. This guide will not focus on designing a sprinkler system, but rather compare and contrast the many sprinkler rotors we offer. This will provide an at-a-glance overview of the rotors and their specifications so you can more easily locate one that will suit your project’s needs.
First, let’s cover some specific specifications that you will be seeing on the charts below.
Drain Check Valve: A drain check valve is simply an internal check valve that keeps water from draining out of the rotor after system shut-down. These are good to have in the rotors that are on low points of the system, but won’t see much use for those at high points unless drainage issues are encountered. Note, on most of our rotor selections you'll need to use the dropdown menu to select the drain check valve, except the few we carry that all come with a drain check valve.
On the comparison chart, you'll see entries like: "Available on 4", 6", 12", this means that there's also non-drain check valve options available for those sizes. If you need a drain check valve, ensure your selection has one. Don't hesitate to email us at firstname.lastname@example.org if you're unsure.
Radius: This will always refer to the throw distance of the spray. It will be over a range, with the lower range usually being achieved with lower PSI and the higher range being achieved with higher PSI. Many also feature an adjustment screw that influences radius beyond just pressure and nozzle choice. Important Note: The throw distance seen on specification charts and performance charts is derived in ideal conditions, usually indoors. This means the throw distance will be less than what you see on spec charts, almost without fail as ideal conditions rarely if ever exist in the field. Keep this in mind when planning your head to head coverage.
Trajectory: This refers to the trajectory of spray. Rotors feature nozzles that are capable of different spray trajectories, such as low angle nozzles and high angle nozzles. On the comparison chart you'll sometimes see two numbers; each one represents a different nozzle, meaning this is not a range of possible trajectories, but rather one of two possible trajectories available depending on the nozzle used.
Arc: The arc specification regards how far the rotor will turn, for example 360° full circle versus 90° ¼ circle. Most rotors feature adjustable arcs across a range.
Operating Pressure: This will always refer to the operating pressure. This will be over a range of pressures the rotor is designed to work within. Note that operating pressure often differs some from recommended pressure. It is advised to operate above the minimum and below the maximum.
Flow Rate: This is the volume of water the rotor emits over a period of time. For rotors, this will almost always be denoted in Gallons per Minute (GPM). Nozzle choice and pressure influence flow rate range.
Inlet: Inlet is, as expected, the inlet size of the rotor. Not the most important specification, but if you’re using all ½” risers it would be very inconvenient to receive all ¾” inlet rotors. Note, all rotor's listed below have female NPT inlets.
Pop-Up: This is the length of the stem that pops up out of the rotor during operation. Common sizes are 4”, 6” and 12”. Shrub models do not pop-up and are usually installed on an above-grade riser. Pop-up size selection is influenced by the area to be watered -- if the rotor needs to spray over some medium height ground cover, a 12” pop-up might be a better choice than a 4”.
Precipitation Rate: Precipitation rate is the rate at which water is applied to a specific area. It is expressed in inches per hour. Precipitation rates depend on the area being watered (which is influenced heavily by the arc adjustment), the nozzle used and the flow rate of the rotor. Having different precipitation rates on the same zone can cause some areas to be wetter than others, possibly wasting water. More in depth information regarding precipitations rates, including the formula used to derive them, will be included below the comparison chart. This is an important specification but requires calculation for accuracy, do not rely solely on the chart for this one as many are expressed as averages or ranges.
Reclaimed Water Cap: This is not included on the chart below but deserves a quick mention. Several rotors are available with purple reclaimed water caps. These caps do not change the performance of the rotor at all, only the aesthetic. The cap indicates that the rotor uses reclaimed water, that is, wastewater that has been reclaimed for use in non-potable applications. If you use reclaimed water, it is advised to ensure it is marked; the purple reclaimed water cap is recognized almost universally as a way to indicate reclaimed water is in use.
When deciding on a sprinkler rotor, each of these specifications will be considered, with flow rate, radius and precipitation rate typically being the primary concerns (though by no means would you want to ignore the rest!).
The chart below includes, at the time of this writing, every rotor we currently carry. It will be updated once a year, usually in the Fall, to reflect new or returning products.
Please note: any of the rotors can be clicked from the left hand column to open a new page that goes directly to their respective item pages. Further specifications and performance data can be found there under the heading "Product Files."
|Rotor||Radius||Flow Rate||Trajectory||Operating Pressure||Adjustable Arc||Check Valve||Inlet Size||Pop-Up Sizes||PR*|
|Hunter I-40 (coming soon)||44'-69'||7.6-29.5 GPM||25°||40-100 PSI||50°-360°||All||1"||4", 6"||0.4 in/hr average|
|Hunter I-25||37'-71'||3.8-31.5 GPM||25°||40-100 PSI||50° to 360°||4", 6"||1"||4", 6"||0.4" in/hr average|
|Hunter I-20||17'-47'||0.36-14.8 GPM||13°/25°||25-70 PSI||50° to 360°||Available on all sizes||3/4"||4", 6", 12", Shrub||0.4 in/hr average|
|Hunter PGP-ADJ||22'-52'||0.5-14.4 GPM||13°/25°||25-70 PSI||40° to 360°||No||3/4"||4"||0.4 in/hr average|
|Hunter PGP Ultra||17'-47'||0.36-18.4 GPM||8°/25°||25-70 PSI||50° to 360°||Available on 4", 12"||3/4"||4", 12", Shrub||0.4 in/hr average|
|Hunter PGJ||15'-37'||0.64-5.3 GPM||18°||20-100 PSI||40° to 360°||Available on 4", 6", 12"||1/2"||4", 6", 12", Shrub||0.6 in/hr average|
|Hunter SRM||15'-30'||0.42-3.4 GPM||14°||20-100 PSI||40° to 360°||No||1/2"||4"||0.6 in/hr|
|HydroRain HRX 075||22'-52'||0.3-9.6 GPM||13°/25°||30-70 PSI||40°-360°||No||3/4"||4"||0.1-1.04 in/hr|
|K-Rain Super Pro||26'-49'||0.5-9.5 GPM||12°/26°||20-70 PSI||40°-360°||Available||3/4"||4.25", Shrub||0.21-1.17 in/hr|
|K-Rain RPS75i||11'-51'||0.35-8.6 GPM||26°||30-70 PSI||40°-360°||Available||3/4"||4"||0.22–1.95 in./hr|
|K-Rain RPS75||22'-51||0.75-8.2 GPM||11°/25°||30-70 PSI||40°-360°||Available||3/4"||4"||0.16-0.99 in/hr|
|K-Rain Mini Pro||17'-30||0.75-3.3 GPM||26°||20-70 PSI||40°-360°||Available||1/2"||4"||0.25-0.35 in/hr|
|RainBird 3500 ||15'-25'||0.54-4.6 GPM||10°/25°||22-55 PSI||40°-360°||Available||1/2"||4"||0.37- 0.83 in/hr|
|39'-81'||3.8-36.3 GPM||25°||50-100 PSI||50°-360°||All||1"||5"||0.48-1.23 in/hr|
|39'-65'||2.9-21.7 GPM||25°||30-90 PSI||40°-360°||All||1"||4"||0.37-1.14 in/hr |
|25'-50'||0.73-9.63 GPM||10°/25°||25-65 PSI||40°-360°||No||3/4"||6"||0.20- 1.01 in/hr|
|20'-51'||1.0-9.5 GPM||13°/25°||20-65 PSI||40°-310° or 360°||4"||3/4"||4", Shrub||0.21-1.02 in/hr|
|Toro T5 Rapid Set||25'-50'||0.74-9.70 GPM||10°/25°||25-65 PSI||40°-360°||Yes||3/4"||5"||0.23-0.86 in/hr|
* Precipitation rates are all approximate/average. See below to calculate more specific precipitation rates.
A note about precipitation rates: You've probably heard the term "matched precipitation." This means that all the sprinklers on a zone should have the same precipitation rate to prevent some areas from receiving too much water in the same amount of time another receives too little. In the chart above these are expressed as either ranges or averages, however it is important to calculate the actual precipitation rates when designing the system.
Here is the formula to determine precipitation rate:
PR = (96.25 * Q) / A
In the formula above, "Q" is the gallons per minute of the rotor (which is determined by the specific rotor used, the nozzle and the pressure at which it is operating). "A" represents the area in square footage of the zone being irrigated. 96.25 (96.30 is often used) is a constant that converts gallons per minute to inches per hour.
Be cautious with high (over 1.0) precipitations rates. Precipitations rates this high are best used with soils that rapidly absorb water. Denser, slower draining soils could experience runoff and erosion if the precipitation rate is too high for its infiltration rate. To some degree this can be ameliorated with shorter watering cycles.
It is possible to have rotors with different spray arcs (90°, 180°, 360°) on the same zone and still match precipitation. As an example, suppose you're using a 360° nozzle with a 4.0 GPM flow rate but needed to include a 90° rotor on the same zone to account for a corner. In this case, you'd use a 1.0 GPM nozzle on that 90° rotor to match the precipitation rate of the 4.0 GPM rotor. The 90° rotor will be applying 1.0 GPM, however it will only be doing so to ¼ of the area the 360° rotor will be covering, thus over the same length of time, their precipitation rate is the same to the area which they are irrigating.
Here is a link to a guide from Hunter Industries that goes deeper into precipitation rates and its importance: Irrigation Notes: The Basics of Matched Precipitation.
Thank you for reading. If you have any questions, comments or feedback, please Contact Us. We read and reply to every message we receive and would love to assist with your questions and learn from your feedback.