SYSTEM DESIGN
a potentially bad receiver on the lateral. Around the panel, make sure any antennas and electronic flow meter signal wires are present and appear in good condition and are free of any damage from rodents or extreme weather.
Running smoothly
Turning the water on, set the VRI controller to manual mode and enable the “pulse” setting. For visual inspections, a good duty cycle for the sprinklers is 80% of five seconds, or on for four seconds and off for one second. Set the irrigation system to move at a speed that will avoid ponding of water on the surface but allow enough time to walk the length of the system before it moves too far from the testing zone. A good note-taking tool during the pulse test can be a photocopy of the system’s sprinkler package, allowing the maintenance technician to indicate the status of each outlet, whether functioning
Getting out into the field and running water through the system for an evaluation is an integral part of maintaining a system.
or not. While walking toward the distal end of the system, be sure to observe at least one pulse cycle for each sprinkler. A single outlet that does not have a pulse, either stuck on or stuck off, generally is indicative of a solenoid valve that needs replacing. On systems with wireless nodes, multiple outlets in a row not pulsing likely indicates that the node’s receiver board has failed and needs to be replaced. When replacing the wireless nodes, be sure to take note of the position of the dip switches on the old board and set it accordingly on the new one. Also, be sure to note the old and new Media Access Control addresses and update the node through either the panel or online interface to ensure connection to the new board. Additionally, check to
ensure sprinkler parts are moving as they should (e.g., rotating) and no leaks are present. Pressure regulators may be more likely to leak and fail on a zone-control VRI system from the continual pulsing of the outlets compared to a steady pressure at the nozzle inlet.
A VRI system adds complexity to a traditional irrigation system maintenance checklist. Most of the necessary additions can easily be incorporated into any operations maintenance checklists to ensure proper operation of their zone- control VRI system.
Eric Wilkening is a graduate research assistant at the University of Nebraska-Lincoln and is available at
ewilkening@huskers.unl.edu.
irrigationtoday.org
Winter 2023 | Irrigation TODAY 25
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