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Research Project: Improved Pest Control Application Technologies for Sustainable Crop Protection

Location: Application Technology Research

Title: Embedded computer controlled premixing inline injection system for air-assisted variable-rate sprayers

Author
item SHEN, YUE - Jiangsu University
item Zhu, Heping

Submitted to: Transactions of the ASABE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/8/2015
Publication Date: 2/24/2015
Publication URL: http://handle.nal.usda.gov/10113/60572
Citation: Shen, Y., Zhu, H. 2015. Embedded computer controlled premixing inline injection system for air-assisted variable-rate sprayers. Transactions of the ASABE. 58(1):39-46.

Interpretive Summary: Conventional sprayers in ornamental nurseries and orchards are grossly inefficient because the same amounts of chemicals are constantly discharged to the field regardless of plant presence, canopy structure, or leaf foliage density. A promising solution is the use of currently available new variable-rate spray technologies that employ intelligent technologies with advanced laser scanning sensors to automatically control spray outputs to match plant presence, canopy characteristics and travel speeds. However, the new spraying systems also encounter excessive tank mixture leftover problems as with conventional sprayers. The reasons are that the required amounts of tank mixtures vary with plant size, shape, foliage density and even growth stage and applicators cannot know how much tank mixture should be prepared before they go to the field. To overcome this challenge, an automatic real-time premixing inline injection system that stores water and chemical concentrates separately in different tanks and mix them directly in spray lines was developed. The new inline injection system is able to maintain consistent chemical concentrations for the variable-rate precision sprayers with a wide dynamic range of spray outputs, and avoids long lag time, inconsistent mixture uniformity and inaccurate chemical flow rate usually associated with conventional direct inline injection systems, resulting in further improvement of spray application efficiency and environmental stewardship for variable-rate precision sprayers.

Technical Abstract: Improvements to reduce chemical waste and environmental pollution for variable-rate sprayers used in orchards and ornamental nurseries require inline injection techniques. A microprocessor controlled premixing inline injection system implementing a ceramic piston chemical metering pump and two small transition tanks was developed for air-assisted variable-rate sprayers. Unlike conventional direct inline injection systems that inject chemical concentrates into the delivery lines, this system first dispensed specific amounts of water and chemical concentrates into an injection chamber and then agitated the mixture in a transition (or premixing) tank. The mixture was then transferred into a second transition (or buffer) tank for discharge from the spray pump. This process was repeated when the buffer tank neared empty. The mixture in the buffer tank was maintained at a constant concentration that allowed the sprayer to discharge a wide dynamic range of variable-rate outputs with a consistent concentration for every nozzle. A touch screen monitor with an embedded computer allowed operators to interface with the injection system. The metering pump accuracy was verified with three simulated pesticides (water, prime oil, and milk). Mixture uniformity consistency was tested with six different viscous simulated pesticides (sucrose solutions) at viscosities ranging from 0.9 to 31.3 Pa s. Test results confirmed that the metering pump accurately dispensed the simulated pesticides at different pump speeds, and the premixing inline injection system provided consistent concentrations of spray mixtures at the spray pump outlet. The new system avoided lag time, inconsistent spray mixture concentrations and inaccurate metering of chemical concentrates at low flow rates associated with conventional direct inline injection systems, and can further improve spray application efficiencies for variable-rate precision sprayers.