Irrigation nozzles are sometimes overlooked in the broader scheme of golf course water management, which could be a critical mistake for superintendents.
Extremely worn or clogged nozzles greatly affect uniformity and turf health, especially if many nozzles are impacted, says Ian Williams, Rain Bird’s national specifications manager-Golf Division.
Extreme misting is a sign of excessive case pressures, Williams says, adding those fine particles are lost to evaporation and susceptible to wind.
“This isn’t a result of nozzle wear as much as it is a sign that the pressure is higher than manufacturer recommendations,” he says. “There could be an issue with the pressure regulation in the sprinkler if it is a valve-in-head.”
Smaller pop-up sprinklers are more susceptible to higher pressures because they are designed to operate at much lower pressures than what exist in a golf course system and therefore must be regulated, he says.
Faulty or old irrigation nozzles use more water, which raises the precipitation rate and increases the water window, says Brian Vinchesi, design engineer for Irrigation Consulting Inc.
“This will lower the uniformity of the sprinklers and cause coverage issues,” Vinchesi says.
In addition to impacting water distribution, a worn nozzle contributes to an increase in sprinkler flow and discrepancies in the irrigation central control systems sprinkler flow database. Faulty irrigation nozzles could lower system operating pressure, which has a negative effect on water distribution, or could trip a low-pressure safety control that causes a pump station to shut off, says Paul Roche, a principal at Golf Water, a golf course irrigation design and consulting firm.
“More commonly, though, is the increased precipitation rates which make the target area wetter, and poor water distribution that contributes to wet and dry areas within the sprinkler pattern,” Roche says.
Because many are made from plastic, OEM golf sprinkler nozzles tend to wear out quickly, says Mark Faris, Underhill International sales and marketing director. He advises superintendents to check sprinkler nozzles every 24 months via a DU (distribution of uniformity) catch can test. Bad nozzle DU performance will require the irrigation system to be left on longer, he says.
“This would cause other issues because some areas would be overwatered and other areas would be underwatered,” he says. “The net effect is a negative water savings and poor agronomic conditions. Another negative factor would be poor course playability.”
Visual inspections show a superintendent the obvious, like damage and wear, but it will take catch-can testing or auditing to determine the DU, says Brent Harvey, owner of Brent Harvey Consulting. “Of course, large uniform circles of wet or dry areas that correspond to your sprinkler spacing is another strong indication that improvements are necessary,” he says. “Nozzles may be the first and least expensive option available for poor DU golf courses.”
Faris advises superintendents to conduct an irrigation audit to reveal nozzle issues.
Irrigation systems dispersing water with high concentrations of suspended abrasive material will require more frequent reviews than systems using potable water, says Jim Wright, product marketing manager for Toro Golf Irrigation.
Select a few representative locations for testing and perform an initial flow and radius test to use as a benchmark, Wright says. “With poor water [quality], test the same locations at two-year intervals that can be adjusted over time based upon results,” he says. “If you are using potable water, every five years would be sufficient.”
Nozzle wear appears as higher overall flows and dry areas close to the sprinkler, Wright says. “The inner nozzles that cover this area have features to place the water in specific locations,” he says. “If these features wear, they will reduce the amount of water falling close to the head and push it further out.”
Wear also shows as a shortening of coverage radius. “Main nozzles have stream straighteners (thin fins) that remove the turbulence and straighten the stream to achieve the greatest distance,” Wright says. “With excessive wear and reduced turbulence reduction the distance of throw will be reduced.”
Of course, large uniform circles of wet or dry areas that correspond to your sprinkler spacing is another strong indication that improvements are necessary. ” -- Brent Harvey, Brent Harvey Consulting
One of the best ways to assess sprinkler nozzle performance is to conduct a water distribution audit. Even more revealing is a before-and-after audit of the same area with existing conditions and after service, Roche says.
In modern systems, hand-held controls – such as radios, phones or tablet devices – allow superintendents to activate sprinklers as they advance from one station to the next. “A distorted pattern, interference of the stream (typically from a low head), or an arc setting out of adjustment is usually quickly identified,” Roche says.
Although time consuming, inspections can take place any time of the day and even during periods of light rain, when nozzles can be inspected and there is good visibility on the sprinkler pattern.
“Simple service, such as confirming and replacing nozzles (if needed), correcting tilted rotors, ensuring arcs are set correctly and cleaning sprinkler screens, can have a very positive impact on water distribution,” Roche says. “Some course management teams elect to inspect three to six holes every month, so the entire property is inspected at least once each year.”
Roche reminds superintendents that one of the biggest impacts on water distribution uniformity is spacing. “A sprinkler cannot be expected to provide good water distribution if it is not located in the right place. Good performance should be expected when spacing is uniform and consistent, that the hydraulic network is sized correctly. In most cases, a sprinkler nozzle cannot overcome poor spacing.”
Proper irrigation is vital to well-conditioned turf, and it is imperative, experts say, that nozzles be checked regularly and replaced when the situation calls for it to insure a uniform flow of water to the golf course.