MP Rotator Adjustment Tool

Arc Adjustment

1. Turn the irrigation zone on so the MP Rotator nozzle is operating and in the fully extended (pop-up) position.
2. Install the MP Rotator with the Left Edge Indicator (the flat side of the nozzle) pointing toward the left boundary of the desired watering pattern.
3. Use the MPTOOL (or your hand) to rotate the Arc Adjustment Ring: turn clockwise to increase the arc, counterclockwise to decrease it.
4. Use the nozzle's built-in ratchet feature to fine-tune left and right edge alignment by gently overriding the resistance points in either direction.

Radius Adjustment

1. The factory setting is full radius. Radius can be reduced by up to 25% using the MPTOOL or a small flat-bladed screwdriver.
2. Locate the Radius Adjustment Screw on the nozzle. Turn it clockwise (up to 4 full turns) to decrease the radius. Turn counterclockwise to restore radius.
3. To achieve maximum radius reduction, use a 30 PSI pressure-regulating spray body. At 40 PSI (recommended operating pressure), radius reduction is approximately 25%.
4. Note: A slip-clutch mechanism in the nozzle intentionally limits reduction beyond 25% to protect the internal components and ensure reliable rotation.

Important: The MP Rotator does not completely shut off like a conventional spray nozzle when the radius screw is turned to the reduction limit — this is normal and by design. Also note that arc adjustments must be made while the nozzle is operating — this is an intentional vandal-resistance feature that prevents unauthorized tampering when the system is off.

The MPTOOL works with all Hunter MP Rotator nozzle models. Use the table below to identify which nozzle is right for your application, then click to shop each model at DripWorks.

All MP Rotator models share a matched precipitation rate of approximately 0.4 in/hr, which means any combination of MP1000, MP2000, MP3000, and Specialty nozzles can be installed on the same zone without uneven watering.

Do I need this tool to adjust MP Rotator nozzles?
Arc adjustment can be done by hand while the nozzle is in its operating (pop-up) position. Radius adjustment can be done with a small flat-bladed screwdriver. However, the MPTOOL makes both adjustments faster, more accurate, and keeps you from having to crouch over a running sprinkler. For contractors adjusting multiple zones, it's an essential time-saver.

Why can't I adjust the arc when the system is off?
This is intentional. The MP Rotator's arc can only be adjusted while the nozzle is running and in its fully extended (pop-up) position. This built-in feature prevents tampering or accidental arc shifts when the system is off — a key vandal-resistance design element that keeps zones calibrated between service visits.

How much can I reduce the radius?
The radius can be reduced by up to 25% using the Radius Adjustment Screw (approximately 4 full clockwise turns). The nozzle's slip-clutch mechanism will stop you from over-reducing, protecting the nozzle from damage. To achieve the maximum 25% reduction, use a 30 PSI pressure-regulating spray body. At higher pressures, the achievable reduction is slightly less.

Will reducing the radius affect the precipitation rate?
No — this is one of the key advantages of the MP Rotator over conventional spray nozzles. The matched precipitation technology automatically adjusts flow as radius changes, so the precipitation rate stays consistent at approximately 0.4 in/hr regardless of arc setting or radius reduction. You won't need to change your run time when trimming back a nozzle's throw.

Does this tool work on MP Rotator Specialty Nozzles (Corner and Strip)?
Yes. The MPTOOL is used to set and verify the arc on MP Corner nozzles (adjustable from 45°–105°) and to adjust the strip radius on MP Strip nozzles (radius adjustable up to 25%). It works across the entire MP Rotator product family.

Do I get one of these for free when I order MP Rotator nozzles?
Yes. DripWorks automatically adds one complimentary MPTOOL to your cart with every qualifying MP Rotator nozzle order. If you need additional tools for a crew or a large installation project, you can purchase extra tools here.

What operating pressure is recommended for MP Rotator nozzles?
The recommended operating pressure is 40 PSI, with an acceptable range of 25–55 PSI. Operating consistently above 55 PSI shortens nozzle life, increases rotation speed, reduces uniformity, and may void the Hunter warranty. If your supply pressure exceeds 55 PSI, install a pressure regulator upstream or use a PRS40 pressure-regulating spray body.

Is there a longer version of this tool so I don't have to bend over?
Yes. Hunter makes the MPSTICK — a kit that assembles into a longer-handle adjustment tool, allowing arc and radius changes while standing upright. This is especially useful for contractors working on large commercial sites. Contact DripWorks if you're interested in this accessory.