Control and delivery systems are vital elements of an irrigation scheme. System components are divided into two major categories: control systems and delivery systems.
Proper installation of system components is critical for a cost-efficient, easily maintained, water conserving, long-lasting system. Safety and reduced liability are also dependent on good installation practices.
Before beginning an installation job, check the static and operating water pressure, flow rate and the size of the water supply to verify that design conditions are the same as actual site conditions.
| A NOZZLE |
FOR EVERY NEED
Selecting the correct nozzle is one of the most crucial, yet overlooked, elements in irrigation system design. Choosing the correct nozzle, whether for a spray head or a rotor, is easy if you take the time to study the nozzle charts in a manufacturer’s product catalog and select the one that best suits your needs since there are nozzles for most applications: Because nozzles are designed to work within a wide range of pressures, ensuring that you have the correct pressure at the base of the nozzle is crucial. Too much pressure, as is commonly the situation with spray heads, will result in misting. Misting creates a reduction in the radius of throw and you may experience uneven coverage and cause wet and dry spots. To correct this, several manufacturers offer devices that can be installed at the nozzle or are integrated in the sprinkler. If you’re working primarily with rotors, keep in mind that too much pressure can cause the rotor to rotate too quickly. The nozzle stream of a fast moving rotor will "horsetail" and cause a severe reduction in the radius of coverage. Too little pressure will also result in a reduction in the radius of throw and uneven water distribution. The author is marketing communications manager for Rain Bird Sales, Azusa, Calif. |
VALVES. Install the zone control valve with the flow control completely open or turned down one or two turns and the top of the flow control 4 inches below the finished grade. This allows the valve box lid to clear the valves while providing good access for maintenance work. Place a resilient seated gate valve upstream of the zone control valve for easy repair and maintenance of the control valve as well as for emergency shutoff.
Place 4 to 6 inches of clean, washed gravel under the valve box for good drainage. Install filter fabric under the gravel and attach it to the valve box with duct tape to keep the soil from working its way up through the gravel or silting in along the pipe and forming a mud hole. Install the valve boxes flush with the finished grade and lightly compact the adjacent soil to prevent settling. Always install sturdy valve boxes to withstand pressure from mowing and maintenance equipment.
Rectangular valve box lids can become difficult to remove because the two longest walls can cave in when excessive pressure is placed against the wall. A piece of rigid PVC pipe can be placed within the valve box between these walls to prevent a cave in.
Coil 2 to 3 feet of control wire around a 1-inch diameter pipe prior to connecting it to the solenoid to allow for valve bonnet removal and to protect the solenoid from electrical surges.
The drip emitter valve assembly should be installed as follows: Install the filter first to keep the rest of the components clean. The filter should have a pressure rating of 125 to 150 pounds per square inch (PSI).
Install the strainer with an easy access flush valve on the top. Next, install a fixed-rate pressure reducing valve upstream from the zone control valve. If installed downstream, pressure surges can occur within the space of time that the regulator takes to set itself after the water is turned on.
A ¼-inch outlet tee with an air valve placed downstream of the control valve is helpful to diagnose future system problems using a pressure gauge.
Any valve, other than the control valves, installed below grade should be installed in a 4-inch to 6-inch diameter PVC pipe access sleeve for valve control. Pipe should be cut out on one end to better fit over the pipe/valve and prevent the sleeve from shifting away from the valve. Center the sleeve on the valve and set it vertically with a 10-inch round valve box at the surface. The larger size sleeve makes it much easier to vacuum or pick stones out of the system.
Backflow preventers should also be placed inside buildings or in shrub beds screen with planting whenever possible. If the backflow preventer is installed in a turf area, pour a 4-inch-thick concrete pad for a mowing strip.
| FROM MY |
|
PERSPECTIVE
For many, the turn of the century represented a time to look back. At Lawn & Landscape, we’re using this occasion as a time to look forward, and we’ve asked key industry personnel to share their thoughts about the future with us. Here, Carl Kah of K-Rain Mfg. shares his thoughts about the future: I have watched the irrigation industry grow over the past 40 years. Strangely enough, I grew up in a house my father built that had an installed sprinkler system. The heavy brass pop-up sprays ran all at one time off of a three-horsepower pump. It was one of the only sprinkler systems in the community. We always had one of the nicest yards in the neighborhood. I’ve watched over the years, as sprinkler systems have become more of a mainstay in our society. Today, irrigation systems are specified in building codes. They’re required for FHA loans. And their use in commercial applications, from factories to shopping centers, has grown tremendously. So has the international market. This is a wonderful time to be in this business. The industry is growing rapidly and so is K-Rain. We’ve sustained an annual growth rate of 25 to 30 percent over the past five years. We’re also aware that more people are working in this field as professionals than ever before. The do-it-yourself market is expanding at a fast pace. All of this is increasing the demand for superior quality products. And this is good. This growth also forces all of us to be sharper. I think it’s essential for installers to understand the importance of selling their service and experience. Naturally, they have to use the best product for the job at hand. But it’s the installer’s experience and expertise that the customer is paying for. Unless contractors make that clear, they’re likely to be selling themselves short – and undermining their value in the customer’s mind. I see many changes and many new opportunities ahead for our industry. With E-commerce, a whole new array of delivery system choices is becoming available, both to contractors and customers. I predict E-commerce to encompass 20 to 30 percent of the market over the next five years. But I still see the majority of the business will continue through wholesale distribution. Distributors provide product along with knowledge and service. Their level of expertise will remain important well into the future. In the end, the best products at the best prices will expand the market around the globe. The end users will have the ultimate choice. Manufacturers will be challenged to do more than keep pace. We’ll have to surpass current standards of excellence with new innovation and even higher levels of performance. We’re excited by the possibilities and gearing up to exceed even our own expectations. The author is chief executive officer of K-Rain Mfg., Riviera Beach, Fla. |
CONTROLLERS. In the case of controllers, be safe. Always ground the controller by using an UL-approved 5/8-inch by 8-foot copper grounding rod and proper ground clamps. Install a protective conduit around wire exposed above ground level. This will protect the wiring as well as provide a better-looking installation.
Pedestal-mounted controllers should be installed on a concrete pad similar to the pad for the backflow preventer. Two sweep elbows should be used, one for the 24-volt wires and another for the 120-volt wiring.
Controllers installed outdoors should have watertight enclosures except in climates where ventilation and cooling of the controller is more important. In addition, avoid installing the controller close to an irrigation head and, if possible, keep it out of exposed turfgrass areas.
All wire connections made below grade should be UL-approved, removable insulated wire nuts installed in a reusable, watertight plastic container filled with a gel and installed in a valve box for future use.
Wire should not be pulled through the ground as this may cause stretching and breaks. Wire can be laid with a cable plow or installed in an open trench. If the wire is installed with the mainline, place it to one side and several inches below the top of the pipe to help protect the wire from damage that may occur from future excavation.
Also, provide a 24-inch expansion loop for wire whenever a change of direction is greater than 40 degrees as well as in situations where the length of wire exceeds 300 feet. Wire that is tightly stretched in a trench may separate within its insulation as soil temperatures cool down.
The author is President of Keesen Water Management, Denver, Colo.
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