Technical
invaluable when calibrating the sprayer and establishing the optimum
charts for each of your nozzle sets, as these will be
“Always keep a record of the spray output
performance for your individual sprayer”
Speed (km/h) Pressure (bar) 025 04 08
Four 2
245 392 784
3
300 480 960
2
196 314 627
Five 3
240 384 768
2
140 224 448
Seven 3
171 274 590
Nozzle output (l/ha) from the Syngenta Turf XC Nozzles at typical spraying speed and pressure. Operators can fine tune application rates during the calibration process by adjusting forward speed and pressure accordingly. A free on-line calculator on the GreenCast website can be used to work out the optimum settings for required outputs
nozzle holder that accepts three or four bayonet housings, where you can fit the required sets and simply twist around to the required nozzle. If not, it is easier if you buy additional sets of nozzle holders, which are relatively cheap, and make them up in the work shop with the seals fitted. Store each set in a separate clear plastic box, with the name and size written on the top, and simply swap over the bayonets to change nozzles, rather than the time consuming and messy job of changing individual nozzles. Always keep a record of the spray output charts for each of your nozzle sets, as these will be invaluable when calibrating the sprayer and establishing the optimum performance for your individual sprayer.
Spray height sets pattern coverage
Nozzle height is a critical factor in achieving even coverage across the turf surface. On flat sports fields and stadia it is relatively straightforward and an even height can be constantly maintained - although take care where the playing area is raised and then drops down a slope at the edges. However, on golf courses where slopes and undulations are integral to creating a challenge for players, the variation in nozzle height can have a profound impact on the spray pattern and consistent application.
“Remember, when measuring the spraying height, it is essential to measure from the tip of the
nozzle to the turf surface, not the boom height”
108 PC DECEMBER/JANUARY 2013
Most nozzles are designed for optimum performance when operating at a height of 50cm above the target, to give a double overlap that minimises any inconsistency in the spray pattern. The problem arises when a sprayer starts to go up a slope, the boom drops down and the nozzle height can drop to 30cm or less. When the sprayer reaches the top of a slope, the nozzle height may jump up to 70cm or more.
The effect will be more severe the
greater the distance between the boom and the rear wheel axle that acts as the pivot point. With self-propelled sprayers this distance can be quite compact but, with utility vehicle or tractor mounted sprayers commonly used on golf courses, the effects can be particularly severe.
Some turf sprayers do now have automatic height-sensing booms, which can be effective at boom leveling when spraying across slopes, but are generally not quick enough to react to sudden changes in slopes. Do check the sensors are kept clean. Testing trials with traditional flat fan nozzles at 30cm spraying height have consistently shown a difference in excess of 25% variation in spray volume across the boom. This has significant implications for product performance of fungicides and fertilisers, if different turf plants are being overdosed or underdosed by this order of magnitude. To overcome this problem the new nozzles have been designed to give a far more consistent spray pattern if the nozzle height falls to 30cm or less. The key is not, as first believed, to simply widen the spray pattern from the standard 110 degrees. Yet, it has required an entirely new approach to the shape of the nozzle orifice - incorporating a unique elliptical design - which ensures a more even distribution of droplets across the spray pattern.
This now give a spray overlap across
three nozzle widths at a nozzle height of 50cm. But, if the height is reduced to 30cm when encountering a slope, it will still maintain a far more consistent and even coverage - typically within two to five % difference across the full spray boom. Remember, when measuring the spraying height, it is essential to measure from the tip of the nozzle to the turf surface, not the boom height - with some machines the nozzle can sit 10 to 15cm below the boom, which would have a significant effect on the spray pattern. Also, check that the boom is horizontal
across its full width; a number of the turf sprayers encountered over the course of testing suffered from droopy booms, with end nozzles five or 10cm lower than those in the middle - which makes consistent application impossible.
One useful tip is to fit our nozzle height indicators onto the boom ends. These flexible plastic ties can be quickly fixed onto the boom, and are pre-marked at five cm intervals - simply line up the
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