Hunter I-20 Rotor, 4" or 6" Rotor with check valve, pressure-regulated body

I-20-04-PRB – 4" Pop-Up, Pressure-Regulated Body with Check Valve

I-20-06-PRB – 6" Pop-Up, Pressure-Regulated Body with Check Valve

* The 4" model (I-20-04-PRB) is recommended for installations in turf with a lower grass height or where minimal burial depth is required. The 6" model (I-20-06-PRB) is preferred in taller turf, groundcover beds, or any application where the riser needs additional height to clear surrounding vegetation.

What does the "PRB" designation mean on the I-20?
PRB stands for Pressure-Regulated Body. The built-in pressure regulator automatically reduces incoming supply pressure — from anywhere between 50 and 100 PSI — to a consistent 45 PSI at the nozzle. This keeps nozzles operating at peak efficiency, produces larger, more uniform water droplets, reduces misting and wind drift, and can save up to 25% more water compared to unregulated rotors running at elevated pressure.

Do I need a minimum pressure differential for the PRB to work?
Yes. The pressure regulator requires a minimum dynamic pressure differential of 15 PSI to engage properly. In practice, this means your supply pressure at the rotor inlet must be at least 60 PSI for the regulator to step down to 45 PSI.

What is the check valve for, and how much elevation does it protect against?
The factory-installed drain check valve prevents water from draining out of the lowest rotors in the system after the zone shuts off — a problem called "low-head drainage." This eliminates wasteful puddling, reduces slipping hazards, and keeps air out of the supply lines. The I-20 PRB's check valve protects against drainage in systems with up to 10 feet of elevation change between the highest and lowest heads in a zone.

What is FloStop® and when would I use it?
FloStop® is a built-in flow shutoff feature unique to the I-20 line. It allows you to close off the water flow at an individual rotor head while the rest of the zone continues to run. This is invaluable when you need to swap a nozzle, adjust arc settings, or perform repairs on one head without shutting down the entire zone — which saves time on service calls and keeps neighboring heads watering.

What is the difference between the 4" and 6" models?
Both the I-20-04-PRB and I-20-06-PRB share identical performance specs (radius, flow, arc range, pressure regulation). The only difference is the pop-up height: 4" for lower-cut turf and areas where minimal riser height is sufficient, and 6" for taller turf, groundcovers, or shrub areas where additional height is needed to clear surrounding vegetation and deliver proper coverage.

How does the automatic arc return work, and why does it matter?
Hunter's patented automatic arc return ensures the rotor's turret always returns to its programmed left-stop, even if someone physically rotates it out of position (through foot traffic, mowing, or vandalism). You never lose your arc setting. This feature also allows you to manually rotate the turret during installation or service without any risk of damage, thanks to the non-strippable drive mechanism.

Which nozzle should I use for my application?
Nozzle selection depends on your desired radius and the spacing of your rotor heads. For standard residential or commercial turf, use the included standard nozzles (25° trajectory) matched to your spacing. For windy environments or areas under tree canopies, low-angle nozzles (13° trajectory) reduce wind interference. Hunter provides a full nozzle performance chart — available in the Downloads section below — covering all 34 nozzle options with radius, flow, and precipitation rate data.

Is the I-20 PRB compatible with a smart irrigation controller?
Yes. The I-20 PRB operates like any standard 3/4" rotor and is fully compatible with all smart irrigation controllers that operate solenoid valves, including systems from Hunter, Rachio, Orbit B-Hyve, and others. DripWorks carries a full range of compatible timers and controllers.

What is the warranty on the I-20 PRB?
Hunter covers the I-20 PRB with a 5-year limited warranty, reflecting the brand's confidence in its commercial-grade build quality.