Submitted to: Transactions of the ASAE
Publication Type: Peer reviewed journal
Publication Acceptance Date: 1/12/1998
Publication Date: N/A
Citation: Interpretive Summary: The sprayer technology of inline injection of pesticides offers many advantages over traditional, single-tank sprayer systems. Problems such as left-over tank mix, application rate errors due to driving speed, and safety hazards from pouring pesticides that are inherent to single tank sprayers can be controlled with inline injection systems. Pesticide application rate can be easily varied while spraying; thus the precise amount of pesticide (or fertilizer) required for each situation can be applied. Pesticides are pumped into individual, small tanks on the sprayer so when spraying is complete, unused pesticide can be returned to the supply container. However, injecting pesticides into the supply line provides less time for complete mixing of sprays before they reach the nozzles. We used a unique, computer controlled system to measure uniformity of mixture for a range of nozzles per boom section, two nozzle supply line sizes and for simulated pesticides with a range of viscosities. We found that the amount of simulated pesticide injected by the piston metering pump did not change significantly with large changes in pesticide viscosity. For the most viscous material, it was necessary to use a spiral mixer in the line to provide a uniform mixture to the nozzles. Mixture uniformity was improved by increasing the number of nozzles in a boom section supplied by one injection point. These results are the first to show how viscosity of the injected material affects mixture uniformity and provides answers for manufacturers on how many nozzles to use on each boom section to assure uniform spray mixtures at the nozzles. These results will be of great value to sprayer designers and should help growers set up field sprayers for optimum performance.
Technical Abstract: Uniformity of the mixture in the laboratory spray boom and across the spray pattern were studied with a turntable sampling system for two to 10 nozzles spaced 50 cm apart in the 5 m spray delivery boom. Three water- soluble liquids (water, Prime Oil and Prime Oil II) and one non-water- soluble liquid (Silicon Oil) with viscosities that ranged from 0.9 to 97.7 mPa s were used as the simulated pesticides in spray delivery booms with 1.07 and 2.09 cm diameters. Viscosity of water-soluble or non-water- soluble liquid only slightly influenced the mean flow rate from the metering pump. The two simulated pesticides with the highest viscosities were difficult to mix with water and it was necessary to use a spiral mixer to maintain a uniform mixture. Increasing the number of active nozzles on the spray boom reduced the variation of the mixture uniformity among nozzles along the spray boom when the carrier rate remained constant. To provide a CV of less than 5.5% for the concentration of the Prime Oil-water mixture required at least six 8002 fan-pattern nozzles on the spray boom.