Whether you're selecting sprinklers for an existing irrigation system or starting from scratch, you have a variety of types and sizes from which to choose. Before you can make the right choice, you've got to do some homework. First consider the size of the area you need to irrigate. Golf courses and athletic fields, for example, will require a completely different system — not to mention a completely different design — than that for shrubs, ground covers and small-area turf. You also must determine site conditions, including the water-infiltration rate of the soil, water quality, water pressure and a variety of other variables that could have an impact on irrigation. All of these elements are critical factors in sprinkler selection. Once you have a thorough understanding of your irrigation needs, then you can begin to determine what type of system it requires.
There are, essentially, three types of sprinklers: spray heads, impact heads and rotary heads. Of these, spray heads are the smallest and are designed for small-area irrigation, while rotary heads are available that can irrigate small areas or large areas. Medium gear-driven rotors are suitable for small-to-medium turf areas and large turf rotors are more appropriate for public parks or golf courses. For the purposes of this article, we will concentrate on those sprinklers designed to irrigate smaller areas and residential turf.
Spray heads are the most common types of sprinklers used for residential turf, and are what most people picture when they think about sprinklers. They generally are of the “pop-up” variety, which are built using risers that are designed to pop up to irrigate 2 to 12 inches above the ground. The height of pop-up should be determined by the height of the surrounding turf, shrubs or other groundcover. Short turf, for example, would require the sprinkler to pop up only several inches. However, if you're irrigating flower beds or shrubs, select a spray head with a pop-up height of 6 to 12 inches. Once the irrigation cycle is complete, decreasing water pressure causes the riser to retract back into its housing at ground level.
While there are a variety of sizes and nozzles available for spray-head sprinklers, most have a maximum throw of 18 feet and provide continuous water spray. Because they are stationary and have no moving parts other than the pop-up risers, spray heads are the least expensive sprinklers.
The rotary club
Rotary sprinklers are more diverse than spray heads and are able to irrigate small areas or large areas, depending on the size of the rotary head. Medium-sized rotors are capable of handling most irrigation needs for small-to-medium-sized turf areas, with a radius throw of 15 to 60 feet or more and water flows as little as 1 to as much as 30 gallons per minute. Like spray heads, rotaries also are available as pop-ups, and are divided into two types: impact and gear-driven.
Impact rotor heads are designed with a spring-loaded arm that disrupts the stream of water flowing from the head, causing the sprinkler to rotate (and causing the swish-swish sound that we all associate with these sprinklers). Depending on your irrigation design, you can adjust impact heads to irrigate in a part circle, half circle or full circle. Traditionally, these sprinklers are constructed using metals such as bronze and brass, which are more expensive, but durable; however, plastic impact heads are now available and are less expensive, but also less rugged. These sprinklers are versatile, easy to adjust, resistant to debris build-up and provide good water uniformity; but they're noisy and also require frequent maintenance, as their springs can collect grass and dirt and are susceptible to bends and breaks.
Gear-driven rotors, as the name implies, are designed using gears to propel the sprinkler head. While the concept is the same as that for impact rotor heads, water triggers a turbine in the sprinkler, which, in turn, prompts the gears to rotate the sprinkler head. These sprinklers are the most popular type of rotary, possibly because they offer quiet operation and are low-maintenance (the design ensures that dirt cannot reach the drive mechanism).
The worst thing you can do when choosing a sprinkler head is skip-out on the research. You may be tempted to make your selection based on past preferences alone, without taking into consideration design and site elements. Take the time to seriously consider your area's irrigation needs and consult an irrigation designer or, at the very least, your local distributor of irrigation products.
What: PGM mid-range rotor
Description: A smaller version of Hunter's PGP rotor, the PGM features the same gear-drive system and is designed to irrigate areas that are too large for a spray head and too small for a standard turf rotor. You can install these rotors on the same zone as other Hunter rotary sprinklers. They are available as a shrub head, 4-, 6- or 12-inch pop-up. Depending on your nozzle, you can vary the PGM discharge rate from 0.42 to 3.4 GPM. The PGM features through-the-top radius adjustment from 40 to 360 degrees when operating or retracted. The radius adjustment feature allows you to “fine tune” to keep water off walkways, buildings and other hardscape. A rack of interchangeable, color-coded nozzles is included.
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Who: Irritrol Systems
What: CR500 mid-range rotor
Description: The CR500 is a gear-driven rotor designed for commercial, light commercial and residential applications. Featuring an easy-to-see top-arc indicator, it can be adjusted from 40 to 360 degrees and provides continuous rotation for even coverage when you set it to full-circle operation. In the event that the turret is tampered with, the rotor automatically returns to its pre-set arc. A riser pull-up slot provides easy nozzle removal and insertion, while a heavy-duty retract spring ensures positive pop-down. The rotor has a 5-inch pop-up height, a 7.6-inch overall height and comes with nine interchangeable, reusable standard nozzles. Its operating range is 30 to 70 psi, with optimum operating pressure at 50 psi. It has a radius of 32 to 50 feet, a flow rate of 0.5 to 10 gpm and matched precipitation rates from 0.3 to 0.5 inch per hour at 60 psi.
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Who: Orbit Irrigation Products
What: Saturn III
Description: The Saturn III is a pop-up, gear-driven sprinkler head that includes a pre-installed sprinkler nozzle and offers a smooth rotating spray. It features an adjustable arc from 40 to 360 degrees that you can adjust during operation or when the head is stationary. It is designed for medium-area coverage from 15 to 30 feet and fills the gap between the large-area heads and standard pop-up heads.
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Who: Rain Bird
Description: Available in 2- 4- and 6-inch pop-up heights, the UNI-Spray is designed for shorter or longer turfgrass varieties. A slim profile and small exposed cover make it virtually invisible; however, design and engineering-grade thermo-plastic materials make the sprinkler head strong enough to handle high-pressure and surge conditions. A pressure-activated, multi-function wiper seal limits the flow-by during pop-up, allowing you to install more heads on a valve. The UNI-Spray is available with 10-, 12-, 15- or 18-foot factory-installed variable arc nozzles that are adjustable from 0 to 360 degrees.
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Who: Toro Irrigation
What: EZ Adjust rotor
Description: The EZ Adjust rotor series includes Toro's patented TruJectory adjustment for fine-tuning the trajectory from 5 to 25 degrees. The arc settings range from 30 to 360 degrees, and when set at 360-degree rotation, the sprinkler becomes unidirectional continuing on in one circular path rather than reversing direction. Specialized controls and indicators keep the sprinklers functioning after vandals have tried to interrupt their performance. Smart Arc memory returns the sprinkler to its previously set arc. A slip clutch also assures no damage to the gear if rotated unexpectedly. You can make all sprinkler adjustments from the top of the head with a simple tool or screwdriver. Top-of-rotor controls include an X-Flow shut-off for dry nozzle and arc changes.
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