Top Crop Manager East - March 2009

New Spray Nozzle Technology May Revolutionize Applications

Blair Andrews 0000-00-00 00:00:00

VariTarget could save time, increase efficiency. A new sprayer nozzle technology designed to increase efficacy, efficiency and safety is showing some promising results from field tests done in southwestern Ontario. The VariTarget Nozzle, from Delavan Agspray Products, is attracting interest for its capability to control flow rate while maintaining a proper spray pattern and droplet size across an expected range of flow rates. A key feature of the new nozzle is a flexible orifice that changes in size in response to pressure changes. Four different caps are available that produce various spray qualities: very coarse, coarse, medium and fine. “It’s a totally different nozzle system in that the conventional nozzles have a fixed orifice,” explains Helmut Speiser, field crops engineer with the Ontario Ministry of Agriculture, Food and Rural Affairs. “This one has a plunger that’s controlled by a spring and diaphragm. As liquid flows through, the plunger is moved and allows more liquid through the nozzle orifice. So it’s similar to the old fuel jet in a carbureted engine. As you step on the gas pedal, the fuel jet allows more fuel to get through.” The ability to respond to pressure changes also allows the VariTargets to apply a constant droplet size. Duane Winter, a certified crop advisor and custom applicator with Lakeside Grain and Feed in Forest, Ontario, says optimizing droplet size is important for maintaining the efficacy of the application and reducing the potential for spray drift. He explains that conventional, fixed-orifice nozzle tips put out larger droplets at lower pressures and fine droplets at higher pressures. Spray efficacy can suffer if the droplets become too large and the potential for drifting is increased if the droplets become too fine. “This one VariTarget tip could do the job of three other tips. You don’t have to switch the nozzle body,” says Winter. “All you need to do is just crank a little more pressure to this one tip. And this one tip will put out the same size droplet at a higher volume.” Winter notes this flexibility also adds a new wrinkle to the spraying process: It expands the window of operation of one nozzle. “You could only run certain speeds and certain pressures. You were limited on your flexibility as to how fast or how slow you could drive with one conventional tip before,” notes Winter. “These VariTarget nozzles let that work expand, probably triple, what a conventional tip would do as far as field speeds and operating pressures.” With the conventional tip, Winter says an operator could drive 15 percent slower or 15 percent faster than his desired speed and stay within the working range of the nozzle. The Vari-Target expands that range, with Winter estimating that an operator could drive 40 percent slower or 40 percent faster and still do a consistent job all through that range. According to information from the manufacturer, spray speeds from two to 20 mph with application rates of five to 40 gallons/acre can be achieved without changing nozzles. To get more familiar with the relatively new technology, Winter and his colleagues at Lakeside have conducted field trials on the Vari-Target nozzles. Tests were performed in 2008 using water sensitive paper to help gauge the coverage. Winter says the results were consistent with the company’s assertion. “Their claim was pretty sound. There was some minor variation but not like it would have been with a conventional tip.” In addition to potentially reducing the number of different nozzles required, Winter says the VariTargets, which are not air-inducted tips, also seem to provide good coverage. “With the cost of some of the crop protection products nowadays, we need to be doing a good job. If this can help us do that, it’s going to be one advantage to doing our job better.” With just one year of testing, it is too early to make a judgment on the VariTarget nozzle’s durability, which Winter says could be something to watch if the nozzle is going to replace others and be used more often. “Durability is going to come with time and experience. Guys are going to have to take the tip to someone like Helmut Speiser and let him test these tips in four or five years to see how they are wearing.” Speiser says another issue to watch is how the nozzles and the accompanying caps will be used and how people will set them. He notes the technology is fairly simple to use. How ever, he adds the tips require careful handling. “You can’t torque them down beyond what they should be. There are little indexing marks for alignment. If you go beyond that, you can sort of ruin the performance of the unit.” The VariTarget nozzle is just one example of several nozzles types that have been introduced to the market place in recent years. While research is underway to test claims of reduced spray drift and efficacy, Speiser recommends that growers do their own tests to determine how well the technologies work on their farms. “I always suggest that before you make a whole switch, get your hands on a few nozzles that you’re thinking about and see how it compares.”

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